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Discussion Starter · #1 ·
Hey guys, just wanna know what tips and/or tricks do you all have to prevent leaks on the t/stat housing when doing a stat on your SBF?

Unfortunately, this is my weakness when it comes to working on SBF's. It usually takes me two cracks at it to get the housing to seal up without leaking. I do the elastic band trick to keep the t/stat in position as I install the housing with the gskt.

While getting my 351W engine ready to drop into my "PS" car, my local jobber had a t/stat gskt. for me to try that had a sticky side to it (eliminating the need to use the elastic band to hold the t/stat in place), however I've had it leak twice in the last month. I would notice coolant collecting in the timing chain area below the housing usually after the engine cooled down. While it is running there are no leaks and a few weeks went by between the two times that I've noticed the coolant leakage. Why would it leak one time and not another? very strange. Any ideas?
 

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I haven't had a problem, but this is what I do.

Run the water neck mounting surface over a belt sander to true it up and smooth it. A very thin coat of RTV in the manifold recess that the t-stat seats in. A standard Fel-Pro gasket with some RTV on both side. I always let RTV skin a little before assy. I put the bolts thru the water neck, then gasket over the bolts and on the water neck. Then water neck to intake. I normally am not in a hurry and let it set up overnite. I always use Black Hi-Temp RTV. Never had a problem.

Are you sure the leak you have is at the housing? Sometimes if the hose clamp is not square on the hose, a leak will form on the bottom side of the area under the clamp. It ends up on top of the water pump too.

Good luck.

_________________
My Mustang
My engine

<font size=-1>[ This Message was edited by: mstngjoe on 5/17/02 11:04am ]</font>
 

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Discussion Starter · #3 ·
I'm pretty sure the leak is at the housing and not the upper rad hose where it attaches to the t/stat housing. I do not see any evidence of coolant running down the side of the housing from the hose if it was leaking there. It's just strange that the first time I fired up the car with the engine in I had no leaks at all in the cooling system, two weeks later I noticed the small pool of coolant on top of the timing cover below the housing, I soaked it up with a rag and just 3 days ago I noticed the same thing again while previously I would check under the hood after each time I drive the car and didn't see signs of leakage anywhere.
 

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couls be the bolts came loose, and all thats needed is a tightening. RTV and patients usually all thats needed. Or the mounting surface is warped and leaking after the heat up and cool down cycle.
Good luck sealing.

Rick
 

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If you are using a cast housing and it is pitted from corrosion, a thin layer of rtv may help...
I also hold them in with some rtv in the recess and then put the bolts through and then the gasket and then install....
I have started using a different tstat housing that has an o-ring seal instead of a gasket may want to look into that...
Any speed shop should have one, motorsport makes one (chrome) , and have seen them in the chrome section in some of the autoparts stores...
Good luck....
 

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Also check the clamps on the little bypass hose.If its a chrome housing without the rubber O-ring toss it in the garbage,these are famous for leaking.
 

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If the thermostat housing is old and corroded the thermostat won't seat properly in the housing and will leak.I had the same problem and solved it by replacing the housing.
 

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Discussion Starter · #8 ·
thanks for the answers guys, I think I figured it out yesterday.

BTW, for starters I using the housing off my old 5.0L Mustang (1989) that I removed a few months after getting the car brand new in 89 (so it's been sitting in a small box all this time and is in like new condition)

I had to move the car so the roofers can come and redo the singles on my garage, after firing it up and moving it on to the street I decided to open the hood and take a look and sure enough I noticed a small drip of coolant from the top rad hose where it connects to the t/ stat housing. I checked the hose clamp and it was a little loose (guess they do back off a bit). I tighten all the hose clamps under the hood and now it should be fine but I will keep a check on it the next few times. So it was the clamp for the hose and the housing to manifold surface is totally dry and isn't wet at all.
 
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