Coolant Leak after Tstat Change

[dec322]

I just changed my T-stat and on the way home there was a major leak through the housing (I think). I also replaced the housing gasket. I was a little worried that I might tighten the bolts too tight and screw the gasket up....after it started leaking I stopped, let it cool about 15 minutes, and refilled the radiator (and replaced the cap b/c it broke in my hand). Then I drove home (2 miles) in stop and go traffic and didn't leak another drop.

So, I lost a full gallon in about 8 miles but then lost nothing in the last two miles. When I got home I checked the system and watched everything as I revved the engine...I found no leaks.

My question: Does it take a little while for the gasket to form a good seal? Maybe the leak was happening while the gasket was trying to seal....is this possible?

 

[Henceforward]

Did you not use RTV?

 

[DMAN302]

I usually wait 24 hours before filling the cooling system, keep an eye on it, you may need to reinstall if the leak persists.

 

[dec322]

I didn't use RTV b/c I bought the housing gasket. Plus, I like the idea of a gasket over RTV b/c it feels like I'm super glueing something on with RTV.....just a personal preference thing.

 

[aod92]

I always use a gasket and a little RTV

 

[Quikstang]

Yep, add some rtv with the gasket. And you will be fine.

 

[sunil6784]

The first time I did a t-stat change, I used just the gasket. It leaked pretty abd. I got a new gasket and added some RTV to it and no more leaks.

 

[Roland69]

I just make sure I have a nice clean surface....use a gasket surface disk on a die grinder and clean both surfaces real good and then install the gasket. Never had a leak yet and I have done quite a few thermostats. the odd one I might use some RTV (black RTV called "the right stuff") if the housing is in a tricky spot.

 

[Aryan15]

T-stat

I have heard of them warping before. Maybe it settled for your benefit.

 

[RsStanG1987]

I use Rtv only no bull ****.

 

[MikeC]

Make sure the thermostat did not come out of the recess/groove that it fits into while you were tightening the housing. I had this happen once and it made a nice leak. I like to use Permatex No2 non-hardening gasket sealant on paper gaskets like the housing gasket, also it's pretty stickey so it holds it in place well.

 

[dec322]

Make sure the thermostat did not come out of the recess/groove that it fits into while you were tightening the housing. I had this happen once and it made a nice leak. I like to use Permatex No2 non-hardening gasket sealant on paper gaskets like the housing gasket, also it's pretty stickey so it holds it in place well.

Hmm.....I could see this being the culprit. The whole thing is in a weird place and I wondered if the t-stat could have fallen out a little bit. I guess I'll find out today when I take it to work.

Fortunately this time I've got 2 gallons of coolant in the car to use just in case of an emergency. Yesterday I had to pull over in a church parking lot and have my wife come and rescue me......what would we do without cell phones??

 

[$uperstang]

Yesterday I had to pull over in a church parking lot and have my wife come and rescue me......what would we do without cell phones??

We would find a pay phone

 

[Roland69]

put the T-stat against the housing with an elastic through it and fish the elastic through the housing and a pen or a bolt to the other end to hold the stat in place while you tighten it.....hard to explain but that's how I did mine

 

[MikeC]

put the T-stat against the housing with an elastic through it and fish the elastic through the housing and a pen or a bolt to the other end to hold the stat in place while you tighten it.....hard to explain but that's how I did mine

That's a good idea.

 

[dec322]

Well, I pulled it out again last night. The problem was that the T-stat had fallen out and was stuck between the block and the housing. I just sealed it on with some RTV and put a new gasket on with some RTV. Problem solved.

Side note. The job is much easier with a smaller wrench to fit on that bottom bolt. The first time I did it the wrench I borrowed (I was changing it at work over lunch) was too long and kept hitting the a/c bracket. Smaller wrench at home made all the difference.....thank goodness for rusty old tools.

 

[sunil6784]

Yep, definitlye easier with a smaller wrench. I actually took one of my old 1/2 inch wrenches and cut it in half with a dremel tool because it was such a pain to do with a regular wrench.

 

[mricci]

One tip my fahter showed me working on my ar wtih gaskets is using the gasket and RTV, but tieign a peice of thin thread to hold the gasket in place. It never leaks, and makes sure the gasket stays lined up perfectly. I have used it on many thing and never had a problem.