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Thread: Removing virtually all coolant hoses except 2.. Is this OK?

  1. #1
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    Eliminating virtually all coolant hoses except 2.. Is this OK?

    Hi,

    I'm driving a 1997 323i E36 with M52 single Vanos engine. I experience a small loss of coolant and want to replace all coolant hoses, which are quite old anyway. (I really hope it's not a head or head gasket problem; luckily no signs of that like oil or pressure in coolant or water in oil) [Update 5 April 2018: Did a compression test and all cylinders show equal compression at +/- 11 bar, so head gasket should be in great shape. I'm happy!)

    Then, while thinking this over I thought of the following:
    Since we moved to the Canary Islands (Spain), with on of the best climates in the world, I noticed I haven't used the heater once. Also heating the throttle body makes no sense here.

    Below is a diagram of the coolant hoses of the M52:
    eliminatie_koelslangen.png

    I think I should be able to remove the red hoses and replace them by very small hoses, and have them plugged with an aluminium solid tube or a bolt or something. Hoses 5 and 7 are related to the heater. Hoses 13 and 14 are related to heating the throttle body. So that seems easy enough..

    After figuring that out, I thought: hey, can I also remove the green hoses, number 6 and 8?

    Effectively the engine would only have hoses 1 and 2 connected which go directly to the radiator..
    With the thermostat closed, the coolant will just circulate inside the head and nowhere else. Once the thermostat opens, it will also circulate through the radiator.. Seems OK?

    Is this an option or would this cause trouble?

    Thanks!
    Last edited by ed323i; 04-05-2018 at 04:57 AM.

  2. #2
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    I would have to look into it more closely, and maybe the Euro set up is different, but I think you'll at least need the expansion tank and therefore at least the hoses that connect to that...

  3. #3
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    Thanks! In the Euro version the radiator has the expansion tank integrated in the (driver side of the) radiator...
    This is a photo of a comparable radiator:
    Last edited by ed323i; 02-25-2017 at 10:16 AM.

  4. #4
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    Quote Originally Posted by ed323i View Post
    eliminatie_koelslangen.png

    After figuring that out, I thought: hey, can I also just remove the green hoses, number 6 and 8?

    Effectively the engine would only have hoses 1 and 2 connected which go directly to the radiator..
    With the thermostat closed, the coolant will just circulate inside the head and nowhere else. Once the thermostat opens, it will also circulate through the radiator.. Seems OK?
    No, you still need a pathway from the reservoir to behind the thermostat. That is the hose for filling the system, just like the US version.
    M50 3.0L stroker project: https://imgur.com/a/l8owP?nc=1

    Confucius say: Buy the best, cry only once.

  5. #5
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    Hi. The throttle body need not be heated in warmer climates. So certain hoses can be eliminated.

    From the diagram, hose 12 and 13 can be eliminated. Hose no 5 and 7 supplies cabin heat, if you don't have that you can eliminate it but it is too big and complex a job. Chances of screwing it up are high so better leave it.

    All the other hoses are absolutely necessary and should not be meddled with.

    Eliminating 12 and 13 won't cause circulation problems in the engine. However, unless you are removing the intake to clip the hoses? If not then, stick a thick screw into each one, The head must be large enough to plug the hose. Tape the screw threads, then the screw after insertion. Then finally put the hose clip on it. If you don't do this it will not withstand pressure. Then ziptie it to something nearby under the throttle body. Don't leave it dangline. .

  6. #6
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    You can also route the hoses together. Brass fitting work great for this.

  7. #7
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    Thanks a lot for your replies..
    If I understand right, the head only has a one-way cooling channel, and it needs hoses 6, 8, 13 and 14 connected to circulate the coolant in the head..

    I somehow thought it would circulate within the head, even with virtually all hoses disconnected.. Luckily I didn't give it a try eliminating all the hoses, because the head would have overheated quite fast.

    Eliminating most hoses seemed tempting, because I would be able to eliminate the chance of coolant leakage in the heater and in several hoses.. And I would end up with a more reliable system (less hoses = less chances of hoses leaking)..

    So, what I should do is just replace all hoses if they look old.. And then I could decide to route hoses 13 and 14 together (and mounting the brass fitting to the throttle body)..
    And, if I can come up with a reliable solution I could decide to block hose 5 (going to the heater) near the head and hose 6 where it connects to hose 7 (which goes to the heater).

    Best to also combine the job with replacing the vacuum hoses below the intake manifold..

    Thanks!

  8. #8
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    Quote Originally Posted by ed323i View Post
    If I understand right, the head only has a one-way cooling channel, and it needs hoses 6, 8, 13 and 14 connected to circulate the coolant in the head..
    Not quite.. flow does circulate in the head and you do not need hoses 13 and 14. On earlier cars that line was regulated by a thermostat inside the air filter housing.

    Flow is pumped through the block from the pump, up into the head, and forward to the thermostat housing internally. Then it can exit to radiator or return directly to pump internally. So you only need hoses #1 and #2 for regular circulation. You need hose #8 to connect the reservoir to the system.
    M50 3.0L stroker project: https://imgur.com/a/l8owP?nc=1

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    Quote Originally Posted by carwiz008 View Post
    Flow is pumped through the block from the pump, up into the head, and forward to the thermostat housing internally.
    Which # hose connects to the head directly ? I can't figure it out from the diagram. Thanks.

  10. #10
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    Thanks again!

    So, if I could connect hose #8 to the head, where normally hose #6 is connected, I could reduce the number of hoses to 3: Hoses #1,#2 and #8.. Seems tempting to give that a try.. I like it simple (and reliable) :-) ..

    SBRocket, hose #6 connects directly to the head on the front end of the car. It's a bit difficult to see but you can follow the vertical line that starts at the left of hose #6 (ring #9 to be exact).

    Here's a nice thread with a very nice photo that shows all coolant hoses below the intake manifold: #13
    Here's a direct link to the photo: IMG_0649.png
    Last edited by ed323i; 02-25-2017 at 02:58 PM.

  11. #11
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    Quote Originally Posted by ed323i View Post
    Hi,

    I'm driving a 1997 323i E36 with M52 single Vanos engine. I experience a small loss of coolant and want to replace all coolant hoses, which are quite old anyway.
    I suggest you hold off on replacing hoses. Tighten all hose clips using whatever tools, as best as you can. You will find that more than one will go more than half a turn. And use a new radiator cap and new bleed screw. They will have new O rings and pressure valves. Your leak will probably stop. Its probably antifreeze slowly escaping under high pressure.

    Water levels stabilize at the cold mark when cold. Fill it up to the brim and it will get here within 1 month.
    If it goes below that, and you can't spot a leak, and your hose clips are still tight. Then check headgasket with a compression test and block test.

    - - - Updated - - -

    Quote Originally Posted by ed323i View Post
    SBRocket, hose #6 connects directly to the head on the front end of the car. It's a bit difficult to see but you can follow the vertical line that starts at the left of hose #6 (ring #9 to be exact).
    Thanks found it, but something doesn't seem to be right. There should be a hose feeding af to the middle of the engine directly from the expansion tank. I can't find that. I'll look and repost later.

  12. #12
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    Thanks! I already replaced the radiator cap... I also tightened the easy to access hoses (#1, #2, #8), but will have to do the hoses below the intake manifold and near the firewall..

    The bleed screw, hoewever, might just be the problem: The previous owner inserted a metal bolt instead of the plastic one, so that's not a good seal probably..

  13. #13
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    The bolt would be ok if the o ring around it is in good shape. Another thing you could do is wrap pipe tape around it, like 2 turns. And around the o ring too. That would be good and tight. Then do a cold bleed and watch for a few weeks.

    Those hoses are complicated to do. Better to wait till you need to remove the intake manifold for something else. Then do it all easily and correctly.

    And I don't think the hoses are the problem here. Didn't read your post before replying sorry. I think the problem iis lose coolant hose clips, rad cap and bleed screw. Bleed screw here sounds like a potential weak spot.

    If you can post a zoomed picture of your bolt bleed screw and its o ring that would be great.
    Last edited by SBRocket; 02-25-2017 at 03:39 PM.

  14. #14
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    I inspected a couple of hoses, after some work below the intake manifold (replacing vacuum hose between manifold and fuel pressure regulator, a pain the ass), and I think all of them are made in 1997, the built year of the year.. So a time bomb waiting to happen..

    So, I looked up this thread, and made a new chart, with the hardcore optimal version for warm climates where you never need to warm up the throttle body, and also don't need the heater inside. I can use the air conditioner to clean up the condensation from the windows.

    Hardcore hose elimination chart:
    harcore_eliminated_coolant_hoses.png

    If it's worth the hassle really depends on how high quality/reliable plugs I can make/find, and also if I can find a coolant hose that will fit between the head and the lower radiator driver side tube.. If I would be able to find all these parts, then it would be a perfect solution and it would make the M52 a lot more reliable and easier to work on (for example below the intake manifold, you'd have more working space)..

    Less radical version (using the original BMW hose):
    normal_coolant_hoses_eliminated.png
    With this version, you'd need four plugs, and you'd be able to use the original complex hose (which I'd personally rather see eliminated because of the amount of connections, all potentially causing leaks in the long run)..
    Last edited by ed323i; 04-03-2018 at 11:47 AM.

  15. #15
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    I've found some interesting parts especially made for this purpose... For starters this one:
    https://www.amazon.com/Each-Heater-B.../dp/B0054NCL6E

    And here:
    https://www.carid.com/radiator-hoses...%20Pipe%20Caps

    And even BMW has a factory one, where the output of the thermostat is optional, and hence capped when not used:
    https://www.amazon.com/BMW-Genuine-T.../dp/B00UR4PL1W

    This is the one Turner Motorsport sells.. Looks extremely reliable, and it's even screwed tight with a bolt:
    https://www.turnermotorsport.com/p-3...uine-bmw-part/
    (Alas, no way I could use this on the M52, as there are no holes to put the screws in)

    It's actually used on the M54 in the E60, on the thermostat bypass exit tube in the head.. Interesting.
    http://www.realoem.com/bmw/enUS/show...11#11537519733

    They are called heater bypass caps or bypass pipe caps or blind plugs.
    If I can find the right sizes for the different pipes used in the BMW M52, I'll be able to implement the less radical version easily.
    The other option (preventing the 21 year old rubber hose time bomb) would be to buy all original BMW OEM hoses, which would probably cost me a lot more than a hundred euro's, and would be at least the same amount of work.

    Based on this review, I should go for EPDM caps or silicone caps.. Normal rubber caps would deteriorate too quickly (months)..

    Now I'll have to find out what sizes the pipes are. Does anybody know this? Or I could measure the outside dimension of the hoses (as connected on my M52), and then guess the pipe dimension.
    Last edited by ed323i; 04-03-2018 at 12:00 PM.

  16. #16
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    Okay, I think I've also found the perfect coolant hose, that's reinforced and is bendable in any shape you like (as long as then bends are not too tight).
    Here it is: https://www.viperperformance.co.uk/s...se_120947.html

    So, I'll go for the hardcore version, eliminating both throttle body heating and eliminating the cabin heating hoses. And also eliminating the BMW original complex hose with several exits and replacing it with a very simple Viper superflex hose with only two exits. And perhaps I should just buy a little more of the superflex hoses and replace the 2 big hoses that go to and from the radiator and thermostat. If what the producer is saying is true, I won't have to change the hoses any time in the future, and it won't be much more expensive than using original BMW hoses.

    And, Meyle also makes coolant bypass pipe caps, I discovered. This one is for VW, but if they make one with the right diameter for use on the M52, I think this would also be a reliable solution:
    https://www.ebay.com/p/MEYLE-Engine-...N-VW/661797956

    Okay, important update, added later:
    I discovered that the #6 hose is in fact a metal pipe in the M52 (in the M50 it IS a hose). So that changes things. No need to replace the #6 'hose' which drops the costs a lot, and also it's easier to install two caps on two of the pipes. Or I could ask a welder to adapt the pipe such that it only connects between the head (thermostat bypass) and the radiator, and the excess tubes/pipes are cut off and welded shut.
    Picture: https://www.ecstuning.com/b-mtc-part...531433059~mtc/

    Okay, let's see what the costs are like:
    RealOEM prices if I would replace all coolant hoses, using the original factory setup:
    1 - thermostat hot to radiator hot: $22.64
    2 - radiator cooled down to water pump: $26.42
    5 - back of head to cabin heater valve: $19.95
    6 - complex hose from front head to: heater return pipe, TB return, and radiator lower return: $0.0 because it is a pipe
    7 - cabin heater to hose 6: 10.76
    8 - return hose from hose 6 to radiator: $8.30
    13 - throttle body return to hose 6: $7.73
    14 - head below intake manifold to throttle body: $14.87
    --------------
    Total $110.67 USD and here locally (on a Spanish island) prices are often higher in euro's..
    So I'm looking at some 130-150 euro if I would buy all original hoses..

    And here's the (hardcore not possible, because #6 is pipe, not hose) less radical alternative:
    1 - thermostat hot to radiator hot: $22.64
    2 - radiator cooled down to water pump: $26.42
    8 - return hose from hose 6 to radiator: $8.30
    Two 10mm (3/8") caps (throttle body hoses) and two 19mm (3/4") caps (heater hoses) max $30
    --------------
    Total $87.36 USD

    Seems like a good alternative.. Not so much money saved, but the result will be a more reliable E36, especially if I would ask a welder to modify the #6 pipe (two less caps and clamps).

    Other alternative would be to replace all hoses by a complete silicon set.. Here's one for the E36 M50 engines for like 160 euro.
    https://www.do88.se/en/artiklar/bmw-...ant-hoses.html

    The second blue picture also shows all inner and outer diameters..
    With the M50 (the 2 big diameter hoses are identical to the M52, but the complex one is different), the two big hoses are 40mm on one side and 42mm on the other side. The very complex hose 6 is 19mm, 24mm and 27mm, and 10mm for the throttle body hose. All other TB hoses are 10mm (the M50 has a TB thermostat!)..

    So, to plug the throttle body tube on the head, I'd need a 10mm inner diameter cap (Gates says 3/8 inch = +/- 10mm).
    To plug the heater output tube on the back (firewall side) of the head, I'd need a 19mm cap (Gates says 3/4 inch and 19.1mm).

    Update (also updated above): On the M50 the complex number #6 hose is really a hose.. On the M52 it's a metal pipe!


    If I would adapt/weld the pipe, this would be the result:
    eliminatie_koelslangen_eliminated_hardcore_welded.png

    This would entail a net reduction of 4 hoses (2 heater core hoses, 2 throttle body hoses) and 6 hose clamps. And the heater core would also be out of the loop.. Overall reliability would be greatly improved.. Especially if I would also replace hoses #1, #2 and #8 by silicon versions, which last a lot longer than the original rubber hoses if I'm correct..

    For reference, this is the original setup, realoem link:
    original_coolant_hoses_M52_europe.png
    Last edited by ed323i; 04-04-2018 at 10:34 AM.

  17. #17
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    This is the original pipe #6:
    coolant pipe bmw m52 original.jpg

    And this would be the adapted pipe #6 (Photoshopped):
    coolant pipe bmw m52 adapted.jpg

    I think I'll buy this original #6 pipe from a scrap yard, and then ask a professional welder to adapt it.

    And then I would only need one 10mm cap (3/8"), and one 19mm (3/4") cap of the best material I can find, which I think would be silicone.

    I also found a set of silicone hoses that go from the radiator to the fuel pump/thermostat house (the big #1 and #2 hoses):
    https://www.ebay.ie/itm/ENGINE-RADIA...i/320947293388
    Or: https://www.ebay.com/itm/Silicone-Ra...5/173117442088

    It's the same on the M50,S50 and M52 E36's.

    Or a complete set for the M52 (shipped from Asia):
    https://www.ebay.com/itm/Fits-BMW-3-...9/401507870980

    This Swedish company seems to deliver great quality hoses.. Let's see if they can deliver the three hoses I need:
    https://www.do88.se/en/artiklar/sili...lue/index.html

    The #8 hose is probably 27 inner diameter, 35 mm outer diameter, based on the diameters shown on this pic:
    https://www.do88.se/bilder/artiklar/...-kit175B_2.jpg

    So I could choose to buy a universal 27mm silicone hose like this one:
    https://www.do88.se/en/artiklar/sili...1125-28mm.html

    Relaxed mode: What I also could do is just buy the original BMW OEM hoses #1, #2 and #8.. All three of them can be reached very easily, and can be changed every few years when I would also be changing the coolant anyway (every year or so). At that time I would also inspect the installed caps.. The three hoses together (#1, #2 and #8, Febi Bilstein brand), ordered at autodoc.es would cost 29.36 euro, a bargain. (The two heater hoses would cost 18.62 euro together; and the throttle body hoses I would eliminate in any case so I didn't check those prices).

    I will also replace the CCV and all rubbers and hoses at the same time.. A Febi Bilstein 4-part-set would be 66 euro (parts #1, #2, #3 and #6, realoem).

    Update:
    I've made the decision.
    * I've ordered: Febi Bilstein #1, #2 and #8 hoses of regular quality enforced rubber. And also ordered the CCV kit. Will also buy some flexible BMW vacuum hose to replace hose from manifold to fuel pressure regulator
    * I've sent a local welding shop a price request to shorten the #6 pipe and remove the pipes/splits for the throttle body and the heater return
    * I'm still looking where to buy the blind plugs for the 10mm (3/8") pipe on the head, below the manifold (TB heating, easily reachable) and the blind plug for the 19mm (3/4") pipe on the firewall side of the head (heater output; not so easy to reach, but doable).

    Also, I'm still investigating a small alternative to welding the #6 pipe: To just leave the first two inches of the #6 pipe that attaches to the head (thermostat bypass) (cut off the rest of the #6 pipe) and then buy a Viper superflex hose, and shape and cut it to connect to the lower radiator tube on the driver side. In which case it would be this chart (little remainder of #6 pipe would be in between the #9 o-ring and the new superflex hose):

    But for this to work reliably (without adapters) the pipe width as it connects to the head should be more or less equal to the lower driver side radiator tube/pipe, which I doubt it is..

    Update April 5th:
    Dorman rubber caps are really bad.. Check this (with photo): http://www.classiczcars.com/forums/t...lant-lines-no/ . They die within a couple of months..
    post-24191-14150827835341.jpg

    So I really need to find the proper silicone caps like these https://store.034motorsport.com/cata...pple+Block+Off (except they charge $140 to ship it here) or these: https://www.mcmaster.com/#push-on-caps/=1ca1dto or perhaps these: https://www.stockcap.com/store/silicone-caps.html (or are these too thin)

    Another update April 5th:
    Yeah! I found coolant resistant silicone caps. Here: https://www.ebay.es/itm/190892513049?var=490179641650 and on their own website here: http://www.autosiliconehoses.com/sil...m-to-32mm.html . Prices are okay and shipping costs are low. So perfect! I'll do some more thinking and measuring and then probably order a few 3/8" (10mm), a few 3/4" (19mm). That way, if I can't find a welder or somehow the pipe can't be welded, I can cap the 10mm throttle body and 19mm heater return pipe (Gates confirms 19mm, 3/4") on the #6 pipe. Will probably order today, and then I'll be able to finish the project in one or two weeks when all products have arrived. Great!

    Yet another update April 5th:
    I ordered everything, directly from their website (autosiliconehoses.com). 2x10mm, and both 2x18mm and 2x20mm (to see which fit best on the 19mm tube). I also ordered a 1 meter long 2mm inner diameter silicone vacuum hose and another one of 3mm to replace the fuel pressure regulator vacuum hose. So I can see which fits best (2 or 3mm).

    I also recalculated the amount of hoses and clamps I would eliminate with this procedure:
    * Hose from head, center below manifold to throttle body: Hose + 1 clamp (the other clamp remains and goes on the cap, head side)
    * Hose from throttle body output to #6 pipe 10mm pipe: Hose + 2 clamps
    * Hose from head, firewall side, below manifold to heater valve hot input: Hose + 1 clamp (the other clamp remains and goes on the cap, head side)
    * Hose from heater valve to driver side heater core: Hose + 2 clamps
    * Hose from heater valve to passenger side heater core: Hose + 2 clamps
    * Hose from heater core return pipe to #6 pipe 19mm pipe: Hose + 2 clamps
    ------
    To be eliminated: 6 hoses and 10 clamps, added 2 silicone caps (1x 10mm, 1x19mm)

    If I can't modify/weld the #6 pipe, I will still eliminate 6 hoses and 8 clamps, added 4 silicone caps (2x 10mm, 2x19mm).
    I discovered the #6 pipe is made from aluminum, so it might be a bit difficult to weld.. So perhaps I'll just use the 4 caps.

    A major boost in reliability, as these 6 hoses can't burst anymore and the 8 clamps can't loose torque anymore, potentially causing small leaks.

    And I'll have more working space near the engine, not only because of all the hoses and the cut down #6 pipe, but also because I can remove the heater valves.

    If I want to make the cooling system really reliable, I should also change the original radiator 2 bar cap for the 1.2 bar cap (too lower unnecessary stress on the system), change the water pump and thermostat preventively and replace the thermostat house for a good quality aluminum one. Oh yeah, the most expensive upgrade: the radiator.. Change it for an all aluminum one. I've already replaced quite some plastic BMW radiators in my life.. Those upgrades will have to wait a bit, as I've already bought a completely new suspension (Meyle HD + Bilstein shocks + most front suspension replaceable parts) and haven't really given my wife all financial details yet ;-) ..

    Update April 6th:
    Today I was looking below the manifold to see how much work it's gonna be to install the two silicone end caps on the engine head, once I receive all hoses and end caps in 1-2 weeks. I think with the M52 manifold and the E36 chassis, it should be possible to install the two end caps on the head without removing the intake manifold. Especially when I first remove all heater valve hoses and the heater valves themselves, I think I should be able to unscrew the hose clamp, remove the hose and install the end cap and a new hose clamp, reaching with my right hand below the manifold, from the firewall side. Also, because the M52 manifold is relatively open from above, I can see enough to make it happen. With the M50 or M54 manifold it's a lot more difficult I think. The other end cap, on the head pipe that goes to the throttle body, it's easy.. I can reach it easily from the radiator side of the engine bay.

    This is probably what the end result will be, as it proves slightly difficult finding a aluminum welder willing to do the job (with reliable results):
    Last edited by ed323i; 04-06-2018 at 06:38 PM. Reason: 2nd update april 5th, ordered the caps + recalc

  18. #18
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    Still waiting for the silicone caps.. Alas the UK company has trouble getting them shipped to the Canary Islands, due to tax/customs trouble.

    But I had a nice idea in the meantime.. I'm working on the fan delete mod, and discovered the engine would overheat, because the temperature switch isn't working.. I've modified the FDM a bit by making the high speed fan turn on at the low temperature setting of the temperature switch.. See https://www.bimmerforums.com/forum/s...-Top-and-Parts .

    Well, I was about to buy another temperature switch, now with the 80/88 temperature settings (which with my mod would trigger the high speed fan at 80 degrees C).
    Then I had a good thought: VDO sells M12 and M14 temperature sensors that also include a small switch at a specific temperature setting. It's ment to light a warning light, but I think it could also be used to trigger the (high speed) fan. That way, measuring the temperature in the head you have a more precise way to control engine temperature, because the 80/88 temperature switch is mounted on the cold side of the radiator, so you never know what the actual temperature inside the head/engine is.

    So, because I'm also removing the coolant hoses to the throttle body anyway, I could remove this part from the head (below the manifold):
    11121740396-1.jpg
    It's number #15 on this realoem page: http://www.realoem.com/bmw/enUS/show...diagId=11_6072 . It connects to the coolant hoses for the throttle body.

    And then install an M12 coolant sensor, which I would then connect to a VDO gauge in the cabin (to get unbuffered temperature readings) and connect the switch to the ground pin of the high speed relay coil.
    Nice part of it all is that I won't need the silicon end cap anymore, because the sensor/switch already closed the hole in the head.

    See page 4 of https://www.vdo-gauges.com/media/ins...rt_version.pdf .

    Bummer, it seems that the sensors with warning switch are only available in M14, not in M12 size..

    I think that putting the switch to control the fan in the head would be a lot better than using the one in the radiator.
    With a 91 degrees C thermostat, you could set the fan switch temperature at 95 or 98 degrees I think.. Or perhaps even lower, not sure..

    Another bummer: it could be that the warning switch in the VDO sensor won't be able to supply ground to the relay coil, because it says "non-inductive".. Not sure if it would work.. Perhaps it only works with led lights or small bulbs.
    Last edited by ed323i; 05-02-2018 at 07:39 PM.

  19. #19
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    That would not be good at all to run the fan from a switch in the cylinder head. You are measuring from one system and controlling a totally different system. The switch is in the radiator because it is meant to control the outlet temperature of the radiator to supply the engine with cool enough coolant to let the cooling system do its job. It really has nothing to do with the temperature of the engine as long as it is doing its job to supply cooled down coolant to the engine. If you put the switch in the head and have it set higher than the thermostat temp the fan won't come on until all of the coolant is way too hot and the system will be way behind by the time it starts.

    I suspect those VDO units are intended to operate a warning light. Which would be excellent to have installed in the head. You are OBD2 I assume so you only have one hole in the head for a sensor and one for the throttle body heater hose. Just an FYI you can use an oil drain plug M12x1.5 with a crush washer to plug the hole in the head where the hose nipple is. Much better than putting a cap on the nipple.
    '94 325i Sedan, Arctic Gray: UUC LTW FW, EVO 3 and DSSR, +.020 Maxsil pistons, ASC delete, Eibach shocks/springs, 16" contour reps 238k
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  20. #20
    Join Date
    Oct 2016
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    1997 BMW E36 323i
    Great explanation.. Thanks!
    I'll let go of that idea (fan temp switch in the head instead of in radiator), but it was an interesting thought :-)

    Alas, today is a holiday, so was unable to buy the temp switch.. So, I hard wired the low speed relay to turn on once the ignition is on (pin #86b is now connected to ground always).. That works good enough, and the temp gauge didn't move more than a tiny bit beyond dead center.. But I noticed the engine is running hotter than a week ago, so I think the temperature stress of my previous test (where I detected the fan would never turn on) "recalibrated" (read: it's probably way too old and the high, uncommon temperature disturbed the internals/wax too much) the thermostat to something like 100 or 105 degrees C. Even on the high way, cruising at 100 km/h (60 mph) the temperature gauge would remain just a tid bit to the right of dead center, whereas before it was always on exactly dead center.. Luckily, I trained my wife to watch the temperature gauge like a fighter pilot, and she's done a great job spotting this difference :-) .

    Luckily I still have a new thermostat lying around, which I planned to install once I would receive all silicone caps for the cooling system mod, but I'll replace it tomorrow.. It's the normal 91 degrees C one.

    I also understand now that the low speed fan moves sufficient air for most situations. It even works better than a mechanical fan without the fan shroud installed, which I discovered yesterday, as the temp sensor still had a tendency to move/climb beyond dead center after reinstalling the mechanical fan, but without the shroud. Without the shroud the air flow/pull isn't directed to the radiator and the viscous coupling also doesn't heat up quick enough because it's not as exposed to the radiator heat.

    So, learning a lot here.. And also an important lesson: You can destroy your head or head gasket very easily by experimenting with the coolant system.. Beware, especially when you're trying to reinvent the wheel with interesting mods of your own ;-) .

    Tomorrow afternoon (before the weekend, so I won't need the car to drive my daughter to school) I'll:
    * Buy the new fan switch and install it.
    * Replace the wasted thermostat with a new Valeo 91 degrees C one
    * Check the thermostat house, and if needed, also replace that (or do you think I should do that anyway, don't know how old it is)
    * Replace all the coolant hoses connected to the radiator (I already have those waiting to be installed)
    * Refill and bleed the system with demineralized water
    * Install a new vacuum hose from the manifold to the fuel pressure regulator

    I'll first test with the high speed fan mod, and later probably go back to the factory setup, removing the relay wire and replacing the relay (I removed pin 86).

    Once the silicone houses (ever) arrive I'll:
    * Install a VDO sensor (or M12x1.5 oil drain plug) in the M12 head opening instead of the coolant hose to the throttle body (I'd very much like the warning to be an audible warning, some sort of buzzer, at, say 105 degrees; I'll check to see if that would be possible)
    * Install a silicone end cap on the pipe that normally connects to the hose to the throttle body
    * Install a silicone end cap on the head pipe that normally connects to the hose to the heater valve(s) (or can I also put a plug in there)
    * Install a silicone end cap on the pipe that normally connects to the the heater return hose
    * Refill and bleed the system with 75% demineralized water + 25% BMW coolant (it never freezes here except on top of the volcano, but the anti-oxidation property and slightly higher boiling point are positive)

    Thanks again for your quick feedback.
    Last edited by ed323i; 05-03-2018 at 12:04 PM.

  21. #21
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    Quote Originally Posted by ed323i View Post

    So, learning a lot here.. And also an important lesson: You can destroy your head or head gasket very easily by experimenting with the coolant system.. Beware, especially when you're trying to reinvent the wheel with interesting mods of your own ;-) .
    That's what i was trying to save you from FYI the factory gauge is all but useless and has a wide range of temperature that will not move from center. I think 75 to 115 C will all show as centered. So by the time it is past center it is quite hot. Those numbers might be a little off but it is a wide buffer.
    '94 325i Sedan, Arctic Gray: UUC LTW FW, EVO 3 and DSSR, +.020 Maxsil pistons, ASC delete, Eibach shocks/springs, 16" contour reps 238k
    '93 325is Coupe, Schwarz, work beater 299k
    '89 325i Vert, Alpine White: 5spd swapped. Sold
    '04 Toyota Sienna XLE Limited AWD, In progress swapping to M50/G250, http://www.wibimmers.com/board/index...nna-25i-build/
    '05 Volvo V70 R, 6mt, mostly stock, kid hauler 200k Sold
    '85 Toyota LandCruiser: Lifted, gas hog. 205k

  22. #22
    Join Date
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    e36 323i, M3 3.2
    why would you even remove these hoses. i dont see the benefit

  23. #23
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    Another question: Do you know a smart, reliable way to block off the coolant channel in the head, that normally goes to the flange and then the hose to the heater valves?
    Here you can see it, number #3: http://www.realoem.com/bmw/enUS/show...diagId=11_6082

    And here's an image of the flange:
    Attachment 628602

    If I would make a small metal plate with the outside dimensions of the gasket and the two holes exactly where the bolts go, would that work?
    And would it be more reliable (measured in amount of years before it would start to leak) than the silicone end cap connected to the flange?
    I reckon aluminum would be the best, the head also being aluminum (same reaction to heat). The surface would need to be quite flat/polished.

    Thanks!
    Last edited by ed323i; 05-03-2018 at 01:59 PM.

  24. #24
    Join Date
    Oct 2016
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    Samy wrote:
    why would you even remove these hoses. i dont see the benefit

    I just noticed I never ever use the heater here on the island. Perhaps it could come in handy once a year, when we would drive up to the volcano.. But 99.9% of the days I just don't need it. The same for the throttle body heating.. It's useless on this island (Tenerife, Spanish Canary Island, just off the coast of Morocco/Sahara in the Atlantic ocean) with one of the mildest climates in the world.

    But if you look at all the hoses, clamps, the heater core.. All of them are places where a hose can burst, the heater core can create a little crack, a heater valve housing can develop a crack/leak, or a clamp can loosen just a bit too much, and all of these can destroy your engine if you don't watch the temperature gauge at that time..

    All hoses are the original 20 year old hoses, so I'd have to replace all of them, knowing they are there being useless, and adding coolant leak risk. The chances of it going fine for a couple of years after replacing the hoses are big, but IF it goes wrong, it could cause the E36 to turn into a 'total loss' if the head would crack or warp..

    I know I have a small leak somewhere, but it's so small I can't spot it.. So I'd rather just eliminate all unnecessary hoses than replace them..

    P.S. There is one small disadvantage.. I won't be able to use the heater core as a 'backup radiator' if something goes wrong in the cooling system.
    Last edited by ed323i; 05-03-2018 at 02:01 PM.

  25. #25
    Join Date
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    I drove by the local BMW dealer today. There are only two on the island, and neither has any of the parts I need. So, no gasket for the thermostat house, no temp switch for the radiator..
    So I drove by one of the larger universal car parts dealers and they also didn't have the parts. I even asked for a standard/universal M14x1.5 80 or 85 degrees temperature switch, and they couldn't help me. Luckily they did have a 3mm inner diameter vacuum hose, so I can at least repair the rich idle/low-load running.

    But, come on, there are quite some older BMW's driving around here, and the BMW dealers don't even stock the regular maintenance items like gaskets for the thermostat house.. It really amazed me.. Would have to wait 1-2 weeks for them to arrive, so I decided not to order, and order it myself in Germany, knowing it would be here in less than a week.. Still a long time if the thermostat is bad..

    But, I decided to do a test. I drove the car around, and made sure it was fully at operating temperature. Then I turned it off, connected the INPA laptop. And it read 89 degrees C for the coolant, while the temp gauge showed as a hair to the right of dead center.. So it seems the thermostat is working fine after all (opening at 91 degrees C, and then receiving nice and cool radiator water, because the low speed fan is now constantly on)..

    So, I don't think I have to rush it. Tomorrow I'll install the vacuum hose, and I'll wait for +/- a week for the fan switch and gasket to arrive before installing the new thermostat, fan switch and new coolant hoses.
    I'll do some more temperature tests tomorrow.. Alas, my INPA laptop is not able to read live data once the car is started.. I think the cheap ebay Chinese USB OBD cable is the cause; it's not properly shielded, or the USB-serial chip is too sensitive.. I think the sparking coils (the 20 pin diagnostics connector is right next to the cables going to the coils) add too much noise and the communication gets disturbed.. But, if I drive around, park the car, stop the engine, connect the laptop and read the temperature, it should be spot on.. It won't loose more than 1-2 degrees C in that short time span after turning off the engine.

    I think (and hope) that my wife and I were a bit spooked by the needle of the temp gauge moving to the white line right of dead center, and now we're watching the temp gauge too nervously.. I think it always ran like that now, just a hair past dead center. And it seems the Euro E36's have a smaller buffer in the temp gauge, just like the European 286HP S50 M3 has an even smaller buffer.. Take a look at another thread about removing the buffer from the temp gauge..
    Last edited by ed323i; 05-04-2018 at 09:29 PM.

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