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Thermostat Housing Still Leaking After Installation...

N

NeXJ

NAXJA Forum User
Location
Los Angeles
I installed a new t-stat after having done a new water pump and fan clutch this weekend... and it took me forever. Anyway, after refilling and firing up the t-stat housing started leaking water at the lower right corner of the housing. I don't understand it. I scraped and even sanded the appropriate surfaces to make sure they were clean, I RTV'ed both sides of the gasket, everything... well thank god it's not the water pump seal since that would mean another six or seven hours... anybody ever have this happen before? Should I just take it off again and throw in way more RTV?? I used a very thin layer on the gasket surfaces...

any help would be great.
 
Last edited by a moderator:
Re: Thermostat housing pissing after install... PITA - advice?

should i use gobs of RTV? I took it apart again and of course it ripped apart the gasket... so I guess I'll put in a new one tomorrow... but I don't EVER remember this happening to the t-stat housing... I was trying to be properly sparing with the RTV this time though....
 
Re: Thermostat housing pissing after install... PITA - advice?

thin smear of RTV on both sides of gasket,
let it cure a bit and fit,
do up the t'stat bolts evenly and gently ...... Shouldnt be a problem ...


Thermostat was sitting in the lip properly ??
T'stat housing not cracked ??
 
Re: Thermostat housing pissing after install... PITA - advice?

it was a bit of clumsy job getting it in there (the t-stat) so maybe it was off-center or something...? hard to say. No cracks that I know of. This is the first time it's happened - and since it was spraying out of one side (corner) it makes me think it didn't mate well somehow. But i have NO idea how one's supposed to get the t-stat seated properly when you have to be paying attention to multiple surfaces at the same time, ensure that the gasket doesn't move, and hold the t-stat in with your third hand while trying to get the bolt holes to align... ack. Maybe there's an argument for partial curing right there... again - it's been awhile since I did the last one... so I could be out of practice...

thanks for the suggestions
 
Re: Thermostat housing pissing after install... PITA - advice?

Look at the housing very closely. It's probably cracked or badly pitted. You shouldn't need gobs of silicone to seal it.
 
Re: Thermostat housing pissing after install... PITA - advice?

I had this problem - drove me mad (especially when, @ the umpteenth attempt, I cracked the housing - best part of a day's travel by public transport accross London to get an other from the only sourse in the metropolis) Not helped by fact the gasket's not readilly available.

Even when I thought I'd solved the problem (meant leaving it overnight for sealant to cure) a mile up the road I stopped for fuel (only another 219 miles to go!) and it was dripping. Fortunately the bolts just needed another fraction of a turn - I assume as a result of it then being warmed up.

Finally, I found it much easier - and ultimately quicker - to do the job having fremoved the electric fan for access.

Try it, it might work for you - Good Luck!
 
Re: Thermostat housing pissing after install... PITA - advice?

When this happened to me the t-stat wasn't seated correctly. It was captured between the head and housing sealing surfaces.
 
Re: Thermostat housing pissing after install... PITA - advice?

My vote is the thermostat wasn't seating right as well. I usually rtv the edges of the thermostat into the recess in the block(just enough to hold it, do NOT just goop it on there) first then what a moment for it to set a bit. That way I know it will stay while butting on the t-stat housing and gasket. Hasn't failed me yet.
 
Re: Thermostat housing pissing after install... PITA - advice?

I had the exact same thing happen to me the first time I did my thermostat. Turned out to be real simple of a problem for me.

When I drained the coolant a small amount sits in the head right below the thermostat. Once The thermostat and housing were in place the coolant some how seeped out and got the RTV/gasket wet and ruined the seal.

I actually found out by putting it altogether using thermostat housing RTV and let it sit for 24 hours. I took it back off without adding coolant and found the lower part of the opening was soaking wet with coolant. Even though I pulled the lower radiator house and drained all the coolant the head holds some in there. Once the thermostat is off you can shine a light in and see it all. How it manages to get up high enough to ruin the seal is beyond me but it did.

I used a fluid pump to get most of the coolant our from within the head and the problem was solved. Maybe that is your problem too...
 
Re: Thermostat housing pissing after install... PITA - advice?

Talyn said:
When this happened to me the t-stat wasn't seated correctly. It was captured between the head and housing sealing surfaces.
Click to expand...

Yup, this is my bet as well. the T-stat feel out of place and lodged between the housing and the head.

Everything still looked fine, and it will torque down the same, but your actually not mating correctly because the lip of the t-stat is caught between them.
 
Re: Thermostat housing pissing after install... PITA - advice?

Thanks for the thoughts... is there actually a preferred procedure for ensuring the t-stat is correctly seated...? i.e. RTV-ing one side of the gasket to the housing and letting it cure, and then RTV-ing the t-stat to the gasket and cure and THEN doing the housing to engine RTV afterwards?? It seems like an awkward enterprise at best the way I'M doing it..!!
 
Re: Thermostat housing pissing after install... PITA - advice?

My problem is probably along the lines of iwannadie's problem. While i DID get rid of most of the coolant, since i was doing the water pump at the same time, I did NOT cover the gasket with RTV totally. Only a ring around the inner seal, thinking that would be adequate. Also the lower bolt wasn't as tight as it could be. So the bolt permitted seepage across the gasket once I filled the system at which point the gasket was already ruined, that no amount of tightening could fix...
 
Re: Thermostat housing pissing after install... PITA - advice?

If it's in there right you don't need RTV, a plain paper gasket will seal between two flat surfaces perfectly fine.

Actually logic says that if something cannot HELP then the only possible outcomes are BREAKEVEN and WORSE.
 
Re: Thermostat housing pissing after install... PITA - advice?

ehall said:
If it's in there right you don't need RTV, a plain paper gasket will seal between two flat surfaces perfectly fine.

Actually logic says that if something cannot HELP then the only possible outcomes are BREAKEVEN and WORSE.
Click to expand...

No fooling. How in the hell did everyone keep their vehicles from leaking like a sieve before RTV? We did it for years as did our Dads and Grandpas.
 
I:

- Make sure the mating surfaces are clean
- Put a light beat of RTV around the recess where the thermostat goes
- Press the thermostat in place
- Put a light coat of RTV on the engine side of the gasket
- Press the gasket in place
- Wait ten minutes
- Verify that the thermostat is still seated
- Put the thermostat housing in place
- Start the screws
- Hand-tighten the screws until they make contact (helps to hold the thermostat housing down with the other hand while you do this)
- Torque the screws (I believe the figure used is 20-25 pound-feet - I go "contact plus one full turn."
- Wait one hour
- Fill it up and check for leaks
- Return to service
 
I had this same problem about 4 months ago. I redid the job every possible way imaginable. Gasket only, rtv only, gasket + rtv, all with a new housing. None of it worked. Finally I said screw it. It leaks a little when the motor is cold then stops leaking when it warms up. It also does not leak when the motor is not running. I've been running it like that in this 105-108 degree average temps in vegas ever since and I still don't have to add any coolant.
 
Thanks for the advice guys... I was just doing it all wrong and trying to seat the t-stat on the gasket on the housing first... instead of on the motor face... makes it far easier...!!
 
Seems like I hit on a common problem - & the right solution the hard way - but it is a little gratifying.

I'm still left with a (a) puzzle: the coolant in the rad looks like clear water, even though the system was filled with a 50-50 mix - & the stuff in the overflow bottle is bright blue!

(b) a minor problem in that over, say, 1000 miles the level drops from "Full" to "Fill" although no apparent leak & no other symptoms except on steep hills or city traffic in hot weather the temp. creeps up enough for the electric fan to kick in. I don't know whethr this problem was present before I flushed/re-filled the system because I hadn't doene enough miles - & it was winter!

BTW - our forefathers (or me, when I started,) didn't need RTV 'cos stats came with gaskets, which were readilly available separately anyway - & could always be replicated from an old manilla envelope!
 
you sure you haven't been putting your wiper fluid in the overflow bottle??? :)

not so sure about the other stuff (except maybe you're not mixing because you're checking prematurely before the t-stat allows mixing to happen) but the apparent volume of the system can vary significantly with engine temp and hose expansion, pressures on the system etc etc.. if you always check at the same time of day when everything's been cool for 8 hours... you shouldn't see a whole lot of level change, if i'm not mistaken...
 
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