Aftermarket Aluminum Water Outlet/T-stat Housing "upgrade" is leaking

[zardano]

3 years ago, I bought the E-36 cooling kit special from bimmerparts.com. It comes with an aluminum t-stat housing to replace the OEM plastic one, the theory being that the plastic ones are risky because they can crack or break, and are prone to warping over time and thousands of heat cycles.

Well, that thing is leaking. It only leaks under pressure, but sprays a green mist of coolant all over the oil filter housing and alternator. It leaks about a 1/2 quart every 2-3 days.

It's only been about 3 years/20-25k miles since I put it in. I'm going to try to seal around it with RTV sealant until my next coolant flush, and failing that, I will replace it with the OEM plastic from the dealer.

Has anyone else had this issue come up?

[lightflyer1]

Where is it leaking from? Gasket, hose or hole?

[Kraut.Burner]

is the housing cracked? no offense but its most likely installed with a very miniscule offset..... fyi you should of put some instant gasket around it in the first place. just my .02c

[flyfishvt]

Did you install a new gasket for the outlet and oring for the tstat when you installed it?

[pbonsalb]

Autohausaz sells these cheap Ronak castings for $10 now. They have been known to leak. I don't think the castings are well done -- look at the flash on the inside, and some are not perfectly flat on the mating surface. Not sure they are an upgrade. The factory part is better in my opinion.

I detected the leak on mine to be around the outside where it meets the head, on the top. I used Right Stuff gasket maker to seal it. Remove, clean, dry, apply small bead of Right Stuff around outside mating surface, reinstall, torque to spec. You should not overtorque these. I have tried that before and broken the inside casting that holds the odd shaped profile gasket.

[TunedReference]

My aluminum housing has been in for ~15k without leaks so far, but I'll keep an eye on it. Got it from Pelican with no gasket.

[zardano]

Autohausaz sells these cheap Ronak castings for $10 now. They have been known to leak. I don't think the castings are well done -- look at the flash on the inside, and some are not perfectly flat on the mating surface. Not sure they are an upgrade. The factory part is better in my opinion.

Yes, "RONAK". Piece of crap. I'm getting the OEM plastic today. Yes, it was installed with a new gasket, new t-stat and t-stat o-ring when I did it in 06. All bolts were torqued to spec according to Bentley manual.

Thanks for confirming Ronak is junk, pb

[Kraut.Burner]

why would you go back to the plastic?

next time, check out some reputable parts stores, they might be a little more expensive, but its definitely cheaper to replace your t-stat housing than to fix your head because your plastic housing cracked.

the aforementioned stores:

check out pelicanparts.com

bavauto.com

zionsvilleautosport.com

[zardano]

Don't think the plastic will crack. I'll replace it every 6 years or 60k with all the other cooling system components (radiator, water pump, t-stat, housing, hoses, clamps, fan clutch, elec. fan speed switch).

FWIW, the alum. housing at Pelican says "RONAK" too. Not sure if there is even a different manufacturer for it other than that.

[Kraut.Burner]

alrighty.

[uncle]

As a preventative step, I replaced a good plastic housing with a new Ronak aluminum part. It completely corroded thru at the lower radiator hose nipple. Had a hole about 3/8" in diameter. Leaked like crazy. I replaced it with a new plastic part.
I don't know what alloy they are made of, but the one I had practcially disintegrated.

[zardano]

After driving to work today, it's still leaking, even with the new OEM housing and gaskets. It's not leaking as much, but I can see some slight spray on the hoses around the housing and the alternator idler pulley, also steam rising from the engine.

I was very careful to ensure the housing and gaskets seated properly, and all bolts were torqued to spec with my micrometer torque wrench. It should NOT be leaking. The only thing I can think is that the mating surface on the engine is warped or scored, so it's impossible to get a good seal?

I don't know what to do now, I'm so defeated. This is the 3rd time I took apart and installed new parts (and new OEM coolant) to fix this problem. It's also been on-going for over a month. I'm so sick of this damn leak.

I guess I can drain the coolant yet again, remove the housing, and try applying a bead of gasket maker/sealant around the edges of the housing and re-installing it again with new gaskets. Anyone else have a better idea to fix this?

[NHbmw325I]

They make a waterpump/thermostat housing specific rtv sealant. Maybe the cooling system is overpressurizing. Is it definately leaking from the housing?

[zardano]

They make a waterpump/thermostat housing specific rtv sealant. Maybe the cooling system is overpressurizing. Is it definately leaking from the housing?

It's really hard to say for sure. The leak got worse the first time after I replaced only the hoses and didn't touch the aluminum housing. It started leaking out when cold, dripping out, and I found a puddle under the car the day after. I'm thinking that jostling the housing getting the hoses off and on loosened it up more. The leak was definitely coming from the engine, not the radiator.

The new plastic housing is leaking less. It doesn't drip out when cold, only under pressure, and I didn't see as much splatter marks on the hoses and alternator pulley as I did before with the aluminum. All this makes me think its the housing.

Only other thing I can think of is the water pump o-ring, or the block is cracked? I don't think its the water pump though because the spray seems to be higher up, its leaking out on the top-right area mostly. I have seen the largest coolant deposit on the front of the oil filter housing, actually. Could a head gasket leak out the front of the engine instead of into a cylinder? Maybe I'll check compression to verify my head is sealed at least.