ISSUE: Unable to Seal Thermostat Housing

[StephenVA]

Congrats

You will have to repost this or at least bump the thread every 30 days as it is a way too common occurrence on our little 6 bangers.

[siny528i]

- UPDATE three (3) months later...

http://www.bimmerfest.com/forums/sho....php?t=1212905


- The paper gasket at mating surfaces works perfectly, bone-dry, zero leak. - As others have said in other forums, casting for the URO Aluminum Housing is a hit-or-miss thingy, so I see tiny tiny bit of "sweating" after a long drive. Not even a drop, maybe 1/10th of a drop. Coolant level in the reservoir is perfect. I think eventually coolant residue will clog the microscopic pores and the sweating will stop (I may be wrong, please chime in).

- I still stand by this Aluminum Housing, a bit of "sweating" is not an issue for me. Still better than warped plastic housing with drop-by-drop leaking everyday (almost emptying the reservoir a few months ago when I still had the factory plastic housing!). I still recommend Aluminum, this minor sweating is a non-issue for me.

- Please see photos...



Attachment 626221



Attachment 626222

Hey guys,

Aluminum is WAY to go! No matter what.
I am closing to 229k and still no leak...

That minor sweating probably will make me concerned
Where is it coming from? Looks like from the hose...

Btw, your car is a baby at 168k

[cnn]

siny,

That sweating is clearly from the casting. Definitely from the casting and not the hose. I follow this very closely, so I know.

Zero issue b/c at the most it is 1/10th of a drop, I could not even see the sweating itself. I have to look very closely to see just a tiny bit of the "sweat".

I will report back from time to time.

[siny528i]

siny,

That sweating is clearly from the casting. Definitely from the casting and not the hose. I follow this very closely, so I know.

Zero issue b/c at the most it is 1/10th of a drop, I could not even see the sweating itself. I have to look very closely to see just a tiny bit of the "sweat".

I will report back from time to time.

Are you saying that its some kind of crack or something? In this case you need to change it ASAP! Are you sure I am talking to same cnn?

[cnn]

- Not a crack.

- This is a known issue with URO Tstat aluminum housing. It is called casting problem. Most of the time, it is microscopi c porous leak, not a hole but porous. I am not worried.

[Aubergine]

Seeing as how both of my M52 cars have the URO aluminum T-stat housting I am going to pay a lot more attention. I just did one last week and the housing seemed to fit spot on and there was really no corrosion. My other car has developed a leak at the top of the housing so I will pull it apart and see what is going on. Yay!!

[cnn]

- No need to pull it apart, just open the hood and look around.

- For my "microscopic" sweating, I am not worried. I just check coolant level once every 2 weeks.
The reservoir is always full.

- If the microscopic sweating gets worse, I have a plan: I will use the tire patch stuff (small amount of contact cement and a small piece of rubber patch + zip tie or clamp) and it should be good to go. I will keep the group informed if the microscopic sweating gets worse.

[StephenVA]

Easy solution
https://www.flexsealproducts.com/product/flex-tape/

- - - Updated - - -

[Mach540]

Easy solution
https://www.flexsealproducts.com/product/flex-tape/

- - - Updated - - -

Saw a hardware store sign the other day......

"In case you accidentally saw your boat in half, we have Flex-Seal in stock."

[StephenVA]

Ha ha

[cnn]

Haha,

- This is funny, thanks for the "FlexSeal" thingy.

- Right now, the "sweating" is about 1/100 of a drop of water. It is so small that I have to use my finger to wipe it and all I get is a tiny bit of residue.

- I suspect this will close by itself, very much like a tiny bit of leak in the house plumbing and the evaporated residue will seal it off.

- Reservoir is full, at MAX.

- For now, I will put this to rest, there are bigger tings to worry about in life than this sweating business. I will keep the group informed from time to time!!!

[killian665]

Quit peeing in your coolant system and using cheap parts and you won’t have this problem.

[cnn]

Quit peeing in your coolant system and using cheap parts and you won’t have this problem.

I am not sure you are joking or serious.

- Cheap or expensive is not an issue, I can afford BMW OEM plastic housing, the problem with BMW plastic housing: it is warped after 2-3y.

- The URO Aluminum housing has been excellent other than this minor sweating business. At the mating surfaces area, it is bone-dry b/c I used paper gasket + tiny bit of RTV sealant. I am very happy with it.

- If I have to do it again, I would again use this Aluminum housing, no regret whatsoever. I am posting the sweating thingy b/c I am a BMW enthusiast/purist and want to show people the sweating thingy. Nothing else. I am happy.

- So, again, cheap vs expensive...not an issue. I have accomplished my goal of keeping the cooling system up-to-date.



Another trick is to use E36 M50 stuff:
- BMW Aluminum Housing + Paper Gasket.
- BMW Upper Rad hose b/c the M50 housing Left end is shorter than M52 housing, thus the need for longer upper hose from M50.

[killian665]

Quality plastic thermostat housings from Behr and Graf do no warp. I have never seen it happen or heard of that happening ever on any car and I’ve replaced at least a hundred of them. Usually on cars that had a factory plastic housing that had been fine for 15 years. Sounds like more bad forum information.

URO is known Chinese junk, that’s why it doesn’t seal right and “sweats”

[cnn]

- I have have gone through a few BMW OEM Plastic housings. I don't know about Behr and Graf plastic housing.

- You are correct but incorrect...I agree with you that URO brand is generally bad news but...This is just a piece of metal.

- I already took care of the mating surface by sanding it and using paper gasket: bone-dry. The sweating business does not bother me a bit. I'd rather use the URO Aluminum housing than any plastic.

[NJDave]

Just replaced entire thermosat and housing on my '97 e39. Used new Wahler thermostat and O-ring, new BMW genuine thermostat housing with new BWM orange seal gasket, tightend all bolts to 10nm (89 in, lbs), added genuine BMW Cooling fluid .... drove about 3-5 miles and already there was a small leak in the top right bolt (at the engine hanger bracket lower attachment bolt).

The new leak sprayed a very slight cooling fluid on front of engine, and this was a mess to completely remove all the "white aluminum spotting" on most of the front facing engine pieces.
I'm glad I caught this in time, as it would of made a huge mess on the engine aluminum parts and mounted accessories (AC condenser, power steering pump, pulley assemblies, etc.).

So now I've removed the cowling, fan blade, etc, etc. to replace all the gaskets again, and that I've cleaned all the aluminum "white spotting" off.

I'll probably use some light sealer gasket this time too. But what I just ordered is what I'm really waiting for ..... is a FULL "OLD SCHOOL" gasket for the entire thermostat housing
(that supposedly works in conjunction with the original thermostat O-ring and orange style gasket).

The "FULL" gasket is only available from one supplier that I could find: "http://abbes-performance.com".

The FULL gasket seems like a great idea to fully seal the thermostat housing, along with a thin layer of Permatex gasket sealer. The gasket is reasonably priced and available to ship to the U.S..
I've just ordered (3) of these to have on hand for future thermostat changes. They shipped them the same day of order, so I expect the gaskets to arrive in a week or so from the U.K.

This is the web link for the gasket:
http://abbes-performance.com/uprated...ket&results=17
(Gasket image attached to this posting)

ANYONE ALREADY USING THESE FULL M52 THERMOSTAT HOUSING GASKETS ?

[siny528i]

I am not sure if you need to go THAT extra step with this gasket.
I understand your frustration as I have been there myself, BUT now I got no leak for almost 3 years and over 10k.
If your surfaces are clean and flat, unlike mines, you should be fine with Permatex Waterpump and Thermostat Housing Gasket Maker.
Just do it right way and buy new stuff for this job.
Good Luck!

[NJDave]

So I ordered a Genuine BMW/REIN Thermostat gasket (11 5 31 748047 - for the E34 and E36) ... and am planning on using it on my E39 as an extra step to prevent any possible leaking on installing a new genuine BMW composite thermostat housing.

I took a new sharp X-Acto blade (No. 11), and cut away slight amounts of the gasket where the "orange" gasket sits ,,, to also allow both use of the OE BMW "orange" rubber seal and the flat full seal (see photo). No modifications are needed on the "round" area where the thermostat O-ring sits against.

Using a new sharp X-Acto blade (No. 11), a magnifying head visor (needed to see and closely cut away small sections of the gasket) , and an Alvin cutting board ... I was able to modify the original "orange" gasket area of the gasket. The full rubber gasket is kind of thick and just needs a good amount of pressure with the X-Acto blade tip, to cut through the rubber cleanly. Just make a rough trim line (on the flat gasket) following the installed original "orange" gasket outline, place the gasket on cutting board, and keep slicing away small sections as you go around it, placing the rubber gasket back on the housing, and checking for a slight clearance around the "orange" gasket, re-cut as needed, and repeat till you have a good clearance for the "orange" gasket to expand slightly when compressed

It actually doesn't take all that long to do the modify cutting, for a good fit (half hour or so).

The plan is to also to add a very fine layer of Permatex thermostat housing RTV gasket sealer (gray), to BOTH sides of the gasket.

All this ... should do an excellent job of sealing the thermostat housing from any potential leaks.
I don't want to plan on ever having to clean all the front engine "white spotting" (on aluminum and plastic engine parts and components - BLAH), from a small housing leak ever again! :

Why BMW never originally took this additional step of a flat gasket, I'll never understand!!

NOTE: This "flat gasket modification" would also no doubt, work especially well for using the Aluminum Thermostat Housings. I also have a new aluminum thermostat housing but for now, decided to go with the OE BMW composite housing.

[siny528i]

Good luck, Dave!
Let us know how it will do!

[cnn]

...The "FULL" gasket is only available from one supplier that I could find: "http://abbes-performance.com".

The FULL gasket seems like a great idea to fully seal the thermostat housing, along with a thin layer of Permatex gasket sealer. The gasket is reasonably priced and available to ship to the U.S..
I've just ordered (3) of these to have on hand for future thermostat changes. They shipped them the same day of order, so I expect the gaskets to arrive in a week or so from the U.K...

No need to buy from the UK.

You can buy it from the US, the E34-E36 M50 gasket (BMW PN 11531748047) is $1 from rmeuropean.com, eeuroparts.com etc.

[siny528i]

8 years later my E39 at 264473 and still no leaks...

[CPHES]

Wow - that’s follow up - good to know

[jicaino]

Thanks for this thread. I was having weird issues with my 6cyl drinking a cup of coolant every 2/3 weeks and my mind always likes ugly and cinokez explanations/theories. Checked and sure enough I have an ever so slightly sweat around the housing.

[Vipernrs3]

[QUOTE=siny528i;29034436]Hello guys,

Yesterday I filled with new Antifreeze + Distilled Water (50/50) and bled it.
Sorry it took me some time because I was kinda away.

Anyway, as I was advised here in my situation...
Attachment 721025


I applied thin layer of J-B Weld 8265S Original Steel Reinforced Epoxy Twin Pack:

Attachment 721021

Left it overnight and then, when it was dry, made it "flat,flat,flat" with 320 sanding block:
Attachment 721022


I also prep the surface of Thermostat Housing. Before it had a free play on flat surface.
I used the trick (thanks to cnn) with 600 sand paper on a table and sanded the surface of Thermostat Housing until it became smooth and flat.

I checked it on few glass surfaces and finally on Engine Block itself where its suppose to go. No free play!

I decided to use Permatex Waterpump and Thermostat Housing Gasket Maker:
Attachment 721023


I applied approx. 1/8 bead on Thermostat Housing. Immediately assemble the Housing while Silicone still wet.
Finger tighten until material begins to squeeze out around flange. Then in 1 hour I tighten at 10 Nm.

I gotta tell you that normally I used more torque (about 20 Nm) on Thermostat Housing.
Maybe that was another reason it failed too soon?

It was a Silicone specifically dedicated for this purpose. It was fresh and when dried became like hard rubber:


Attachment 721026

Since 2015-12-27 it was sitting like this and, like I said before, only tomorrow I was able to fill and bleed it.

I hope its going to last longer than last time![/QUOTE

Just curious, has this held up still, just found a issue of this nature on mine, but worse, and trying to avoid buying a new head