Page 1 of 2 12 LastLast
Results 1 to 25 of 40

Thread: coolant leaking - never ending

  1. #1
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i

    coolant leaking - never ending

    LATEST:

    I found a much bigger constant dripping from behind engine, above transmission pan.
    From above, I can see coolant accumulate below at back of engine, driver side.

    I barely squeeze myself under it but can't see exact the location. I can see some coolant on a hose affected by the leak though, seems like hose connecting to part#3 at https://www.realoem.com/bmw/enUS/sho...diagId=11_6082
    From my research I find it might be the hose to heat core. I will take out air intake chute to check them out.
    Do I need to buy new hoses or just tighten them as I didn't replace them when I did coolant system overhaul 2 years ago?



    ORIGINAL POST:
    I had coolant leaking for quite a while now. After I replaced both hoses connecting to the thermostat, I find the throttle housing # (I think that's the name, connecting to the mass air intake hose) is leaking coolant during pressure test. There are 2 small hoses connecting to it. I don't understand why coolant goes there. The mechanic told me it's not the hose leaking, it's leaking inside the assembly and I have to replace the whole thing.
    realoem diagram http://www.realoem.com/bmw/enUS/show...diagId=13_1707
    My question is
    1. why coolant go there? google told me some car use coolant to warm the throttle body, not sure if this is the case for E36.
    2. how can I tell if it's hose or assembly leaking? I plan to use white tape to re-tighten the hose to check out.
    3. Since it's quite expensive part, is it rebuildable? Another choice is to buy used parts.
    Thanks.
    Last edited by yxd0018; 01-30-2019 at 10:59 AM.

  2. #2
    Join Date
    Jun 2010
    Location
    NY
    Posts
    9,066
    My Cars
    1997 328i
    I would buy one off ebay. It's fine to get a used part for something like this. Yes, it's very odd for the throttle housing to fracture, make sure your coolant is good. That's the only thing I can think of, if your coolant is bad then the freezing point can be reached. You can bypass the throttle body if you want, but since your in NY area and things get quite cold up here it would be better to leave it stock.

    https://www.ebay.com/itm/BMW-E36-Z3-...n/161631182804
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
    Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".

  3. #3
    Join Date
    Oct 2003
    Location
    New Zealand
    Posts
    266
    My Cars
    1996 E36 M3 Evo
    Unless you live in a sub-zero environment the coolant passthrough for the throttle body is entirely unnecessary... to me it seems like a dumb design decision from BMW (no M3's came with it so it can't be essential).

    You can simply bypass it, just buy some suitable hose and loop it outside of the throttle body.

    Edit: you'll need to bleed the cooling system after doing this.
    Last edited by M3AN; 01-30-2019 at 06:27 AM.
    '96 M3, S50B32, 6MT
    + good stuff

  4. #4
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    I use white tape to re-tighten the hose. When I open the hose, there is no coolant. Not sure if this is normal. Pressure test shows no leak.
    However I found constant dripping from behind engine, above transmission pan.
    From above, I can see coolant accumulate below at back of engine, driver side.
    coolant_leak.jpg
    I barely squeeze myself under it but can't see exact the location. I can see some coolant on a hose affected by the leak though, seems like hose connecting to part#3 at https://www.realoem.com/bmw/enUS/sho...diagId=11_6082
    What could go wrong there? Are those hoses for heater core? like diagram https://www.realoem.com/bmw/enUS/sho...diagId=64_0126 ?

    EDIT: after research, seems might be the hoses to the firewall. I recall my heating doesn't work well, which could be due to the same issue.
    Thx
    Last edited by yxd0018; 01-30-2019 at 10:07 AM.

  5. #5
    Join Date
    Jul 2011
    Location
    Austin, TX
    Posts
    2,169
    My Cars
    S54 E36 M3, E32 740il
    Quote Originally Posted by M3AN View Post
    Unless you live in a sub-zero environment the coolant passthrough for the throttle body is entirely unnecessary... to me it seems like a dumb design decision from BMW (no M3's came with it so it can't be essential).

    You can simply bypass it, just buy some suitable hose and loop it outside of the throttle body.

    Edit: you'll need to bleed the cooling system after doing this.
    Maybe not down there, but in the US they do have it.

    Lots of people bypass it, but with the pressure drop in cold environments (especially a place like new york, cold and humidity) I'd think about fixing it.

    Time for a big bore throttle body!

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  6. #6
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    From my research I find it might be the hose to heat core. I will take out air intake chute to check them out.
    Do I need to buy new hoses or just tighten them as I didn't replace them when I did coolant system overhaul 2 years ago?

  7. #7
    Join Date
    Oct 2003
    Location
    New Zealand
    Posts
    266
    My Cars
    1996 E36 M3 Evo
    Quote Originally Posted by blckstrm View Post
    Maybe not down there, but in the US they do have it.
    Noted and accepted.

    Perhaps I should have said "proper" M3's with ITB's like those sold in all climates across the rest of the world.
    Last edited by M3AN; 01-30-2019 at 10:29 PM.
    '96 M3, S50B32, 6MT
    + good stuff

  8. #8
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    I remove the cabin air firewall between cabin and engine room to see the leak. With radiator pressure on, I don't see any leak in 3 hoses to the firewall and 3 hoses to the water valve. When I run the engine at normal temperature with heating to max and volume to max, I still don't see leak as I saw last time. However there is little heat coming out. I pedaled the gas for a bit and still no leak and only a little heat coming out. I remember the heat was weak during normal driving. Give this two days are freezingly cold, heat becomes the biggest issue.
    Besides I go out and drive a bit then come back to hook up radiator leak kit, is there a usual suspect based on my observation?

    From my last post, when I open the 2 hoses connecting to the throttle, I don't see any coolant. Is it an issue?
    Last edited by yxd0018; 02-02-2019 at 08:27 AM.

  9. #9
    Join Date
    Jun 2005
    Location
    New England
    Posts
    25,385
    My Cars
    F90 M5; E36 M3 Turbo
    I live in NH and drive year round and bypassed my TB coolant lines over 10 years ago. I would do that for an easy test, and bleed the system. If you are not getting heat, you have air in the system and are at risk of an overheat. The other explanation for little heat is a failed heater control valve, which could explain the coolant drip at the back of the motor if it is running along the underside of the hose and then dripping closer to the motor.

    A broken water pump impeller is possible but I think the motor would be overheating. It’s not common.

  10. #10
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    Thanks. When I replaced thermostat housing and hoses, I bleeded the system without jack stand. Maybe I should do it again with jack stand. I haven't experienced overheating so far.
    I would run the car normally during the day and hope I can see the leaks when I come back.

    EDIT: for water valve, I guess there is no other choice but to dissemble to inspect it.
    Last edited by yxd0018; 02-02-2019 at 10:16 AM.

  11. #11
    Join Date
    Jun 2005
    Location
    New England
    Posts
    25,385
    My Cars
    F90 M5; E36 M3 Turbo
    A few have rebuilt them. I attempted to take one apart but was unsuccessful. A member named flyfishvt may have posted details years ago.

  12. #12
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    Sorry for the wrong word. What I meant is I have to take out that part to inspect it. Saw one video and that's not easy fix. new one from eBay only cost $40. Only thing is I'm not so sure the water valve is broken even I see some leaking.

  13. #13
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    I jacked up the front and bleeded again with max heat for 30min. Even there are some air, I don't see the leak I saw before and heating is still not working. So next step is to swap the heat valve?


    Quote Originally Posted by pbonsalb View Post
    I live in NH and drive year round and bypassed my TB coolant lines over 10 years ago. I would do that for an easy test, and bleed the system. If you are not getting heat, you have air in the system and are at risk of an overheat. The other explanation for little heat is a failed heater control valve, which could explain the coolant drip at the back of the motor if it is running along the underside of the hose and then dripping closer to the motor.

    A broken water pump impeller is possible but I think the motor would be overheating. It’s not common.

  14. #14
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    I failed to make the rear of engine leak coolant again. However the little plastic nob on the radiator for the small hose is broken. So ordered radiator from FCP and more work to go.
    Is it possible the leak is inside heat core? Should I see a lot of liquid under the dashboard? I feel nothing, but see coolant dropping.
    I use regular clamp for the hose connecting to the thermostat housing. My friend told me I should use spring clamp instead as it will adjust tension better during temperature change. Is it true?

  15. #15
    Join Date
    Jan 2019
    Location
    HK
    Posts
    280
    My Cars
    525
    Quote Originally Posted by yxd0018 View Post
    Thanks. When I replaced thermostat housing and hoses, I bleeded the system without jack stand. Maybe I should do it again with jack stand. I haven't experienced overheating so far. I would run the car normally during the day and hope I can see the leaks when I come back.EDIT: for water valve, I guess there is no other choice but to dissemble to inspect it.
    Just two quick points and I haven't read this entire thread apologies if this has already been covered.

    Firstly there is no need and there has never been any need to put the car on jackstands or on an incline, to bleed the radiator. The engine in the bay is already on an incline to the front. This is to enable trapped air bubbles to move to the front. There they are pushed out to the expansion tank by the pump and replaced by coolant drawn in from the expansion tank.

    That's why bentley says open the heater valves with current on and bleed screw and fill up with coolant till no bubbles run out. You can also run the engine at idle while doing this. Then go for a drive with the heater on and the next day just open the expansion tank and fill up to the brim alone. Any trapped bubbles would have migrated to the front. You may "'lose" alot of coolant due to this, which is why bentley says check and topup the next day.

    Secondly, I had a leak that I could not find when cold. It would happen when hot but would vapourise too quickly and the engine was too hot to feel around properly. I used a radiator pressure testor when cold and the leak reappeared finally. I localised it and fixed it. So if you can borrow that for a day or so and try it when cold you might be able to find the exact spot it leaks from.

  16. #16
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    Thanks for the explanation.
    I used radiator pressure kit to check leaking. But i haven't found the issue I observed earlier. Since my heat doesn't work well and the location I saw leak was at rear of engine, I suspect the heat valve or heat core might be the issue .

  17. #17
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    Find this thread explaining the very same low heat issue for e36.
    I guess I need to bleed again with higher rev.
    https://www.bimmerforums.com/forum/s...o-heat-at-idle

  18. #18
    Join Date
    Jan 2019
    Location
    HK
    Posts
    280
    My Cars
    525
    Quote Originally Posted by yxd0018 View Post
    Find this thread explaining the very same low heat issue for e36.I guess I need to bleed again with higher rev.https://www.bimmerforums.com/forum/s...o-heat-at-idle
    That thread is for Z3s not E36s. Won't apply to you.

    What jumped out at me was this :

    Quote Originally Posted by SunzOut View Post
    This problem has now been fixed for me. It was air in the system. The heater has worked fine at idle since I had a coolant flush completed at the local indy BMW shop last week. The heater control also is a little more gradual now rather than the "on/off" that it was before.
    This guy says it was trapped air in the system, but it started working after a coolant flush. I'm sure something was clogged in his heater core that the flush removed. That is probably the issue here for you too. But sure try the 2000rpm bleed since it only takes 5 minutes to do. I think you'll need to flush thoroughly with prestone's super flush to clean out corrosion. I just flush with water, then fill up with the prestone, top off with water, then drive for a bit, then come back and flush. Its fine and you can leave it in there for more than a day, it only attacks corrosion and frankly more time means more circulation and more time to work so I would recommend that.

  19. #19
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    Thanks for the great suggestion. I wonder if my inconsistent heat issue means the heat valve is good? Or I still need to take it out to inspect? Do I need to replace the heat valve as preventative measure?

  20. #20
    Join Date
    Jan 2019
    Location
    HK
    Posts
    280
    My Cars
    525
    Yes I believe that is more than likely. Quite possibly the heater valve is not opening fully. The piston is stuck and doesn't move open properly when the solenoid energises itself to pull it open when you flip the switch to hot. That's why only a trickle of hot coolant goes in at high rpms and none at low rpm.

    Heater valves do not need to be replaced. They can be rebuilt and frankly that gives you more peace of mind, and is of course much cheaper than buying use. Basically the seals and stuff inside become clogged with built up corrosion and dirt because people don't change their coolant on time, or flush their engine with a dedicated flushing fluid on every third coolant refresh.. They just need to be cleaned off. You can have a standby used heater valve that you rebuild ready and waiting, they are cheap like $20-$30 used. Then put it in, rebuild the one you took out, and sell it for $50-$60 as a rebuilt unit, with pictures to prove that you rebuilt it.

    When you take it out, good idea to flush the heater core directly with a hose.

    Hot coolant goes to the heater core due to a combination of 4 forces. The first is the inclination of the engine, which is at about 3 degrees or something to the horizontal (can't quite remember exactly how much). Second is of course the fuel pump. Third is the auxiliary water pump - holy I forgot that. Please test to see if that is working! Fourth factor would be the "backwards"' inertia of the coolant in pipes, when the car is moving forward.

  21. #21
    Join Date
    Oct 2010
    Location
    west new york,nj
    Posts
    287
    My Cars
    328i
    Oh, e36 has auxiliary water pump? Need to look it up. So basically there should be hot air during idle low rpm! ?
    I bought new heat valve from eBay for $40 just in case. I will look up eBay for the rebuild kit. Not sure if it worth the effort.

    EDIT: I don't think e36 has auxiliary water pump. I can't find it in realoem.
    Last edited by yxd0018; 02-07-2019 at 08:50 PM.

  22. #22
    Join Date
    Jan 2019
    Location
    HK
    Posts
    280
    My Cars
    525
    Yes there should be hot air during idle low rpm, once the coolant itself is hot enough. And $40 is a very good deal. Is it oem ?

    Don't bother with the rebuild kit. Open up your old one once removed and see if you feel like rebuilding it. A kit will probably not be necessary.

    My mistake, there is not aux water pump for the E36. Funny they have it for the E34....Oh right I got it. For the E34 the heater valve is high, nearly next to the fuse box. Hot water needs to be pumped up and then back down to the firewall and into the cabin. For the E36, it is low, under the brake booster? So more or less in line with the main coolant hose or slighly lower. No need to pump coolant especially.

  23. #23
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,613
    My Cars
    11/88 E32 750iL+98 E36M3
    Quote Originally Posted by Thomas525 View Post
    My mistake, there is not aux water pump for the E36. Funny they have it for the E34....Oh right I got it. For the E34 the heater valve is high, nearly next to the fuse box. Hot water needs to be pumped up and then back down to the firewall and into the cabin. For the E36, it is low, under the brake booster? So more or less in line with the main coolant hose or slighly lower. No need to pump coolant especially.
    This is to clarify the function of an aux water pump, which is for example installed in E46, E34, E32, Z3, it does not matter where the heater valves are located: The function of an aux water pump is to pump constantly - when the heater is on and the temperature has reached at least 30 degree C.- 950l/h thru the heater valves and heater core, and that is done with an electric motor inside the aux water pump, INDEPENDENT from the RPM of the engine = water pump. Without aux water pump the volume of coolant passing thru the heater core depends on the RPM of the engine.
    https://www.bimmerforums.com/forum/s...ary-water-pump
    Shogun tricks and tips for the E32 series are HERE!

  24. #24
    Join Date
    Jan 2019
    Location
    HK
    Posts
    280
    My Cars
    525
    Are you saying that cars without the aux water pump will not get heat at idle ? Or will not get much heat at idle ? If so, why the heck would they design it that way ?

  25. #25
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,613
    My Cars
    11/88 E32 750iL+98 E36M3
    Cars w/o aux water pump will get less heat/flow at idle into the heater core, as the water pump runs via a belt based on the RPM of the engine. That aux water pump is a comfort item for the more expensive cars like E32, E34, E31 and especially diesel engines to get always 950l/h thru the heater valves and heater core, independent from the RPM of the engine.
    On an E32 you will only feel the difference once the aux water pump fails, then you notice that the heat becomes a bit colder in idle, maybe most people do not notice it at all. But it is technically clear, that a water pump driven via a belt produces more volume/flow at higher engine RPM than at idle.
    copied: These aux water pumps were first used on diesel vehicles in the 1980’s because most diesel engines do not generate a lot of heat when running or idling. Coupled with the lower engine speeds, the coolant in the heater core would lose most of its heat before it passed through to the outlet. This would cause drivers to complain about insufficient heating if they drove in stop-and-go traffic or cruised at speeds with lower RPMs. So, adding an auxiliary coolant pump would provide enough coolant to keep the heater core warm. Mercedes then started to use these pumps on gasoline-powered vehicles like the C- and S-Class for the same purpose allowing vehicle engineers to use larger heater cores to provide better passenger comfort.
    Mercedes, Audi and BMW have also used this pump as part of the automatic temperature control system to keep the cabin heated even after the driver has turned off the ignition. The system can keep the interior warm for short periods of time while the driver goes shopping or grabs a bite to eat.These pumps will show up on more and more vehicles as engines become more efficient and generate less excess heat.
    https://www.knowyourparts.com/techni...y-water-pumps/
    Shogun tricks and tips for the E32 series are HERE!

Page 1 of 2 12 LastLast

Similar Threads

  1. Replies: 16
    Last Post: 07-17-2012, 06:51 PM
  2. Got a coolant leak I've never seen before. Help!
    By BimmerM3inGA in forum 1996 - 2003 (E39)
    Replies: 8
    Last Post: 01-13-2010, 11:03 AM
  3. Coolant leak from back end. Ideas?
    By pimpin.dre in forum 1975 - 1983 (E21)
    Replies: 3
    Last Post: 05-14-2008, 04:23 AM
  4. 325is never-ending tranny leak!!
    By x6lil6billy6x in forum 1983 - 1991 (E30)
    Replies: 2
    Last Post: 08-27-2007, 04:52 PM
  5. Yikes! Never ending power steering leak
    By 318power in forum General BMW Mechanical Help sponsored by RM European Auto Parts
    Replies: 4
    Last Post: 04-08-2003, 07:17 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •