Thermostat leak

There appears to be a leak around my thermostat.  I have tried to tighted it down, but after I drive the car there is still coolent around the thermostat.  I don't see the leak at idle, but driving make everything damp.  Before I take off the connector, what should I look for?  Is there one gasket (under the thermostat) or two (above and below the thermostat)?

Only one gasket involved. Couple of questions, tho...is this an aluminuminum manifold, or cast iron?
Is the thermostat housing original/original style, or aftermarket chrome?
Sometimes, a small leak around the housing will stop after driving a while. If the car doesn't get much use, that can contribute to the leakage. Of it's driven frequently, the gasket will stay pliable, and seal well. If it sits for lengths of time, the gasket tends to shrink somewhat, and you'll see some seepage until it seals again.
If this is an aftermarket chrome housing, the only way you'll ever stop the leakage is to grind/file the bottom of the housing to get the chrome off of it. Chrome doesn't make a very good sealing surface, no matter what kind of sealant you may use. Grinding the chrome off give the gasket a nice, rough-ish surface to seal against.
It's also possible that the housing is warped. This can be made better by filing, also, to get it flat again.
hth

another afterthought....it could also be the hose itself leaking, and running down around the housing. Might wanna check that while you're at it, in case the housing has corroded, and is digging into the hose.
Adams' Apple2011-08-10 10:16:59

P.S. Hose is not leaking.  I can tell by the leak pattern.

You might be able to file the bottom of the housing, if you have a good mill file. Otherwise, I would definitely start looking for a different thermostat housing. Most housings will be aluminuminum to start with....not that that makes any difference. The gasket will separate the two metals, but the bolts will be touching both, anyway. When you get ready to change it, make sure the area is clean...that make the most difference in whether or not they will seal. You might still see a small amount of seepage for the first couple of times you start it, but that will stop...unless there is another issue with either the manifold, or the new housing. If you use a regular, paper style gasket, you can use a SMALL amount of 3M Weatherstrip adhesive on both side of the gasket, and not have to worry about a leak. If you use one of the blue, silicon impregnated gaskets, use it DRY, with no sealer.
hth

Thanks for the help.  This time I buy one of the better quality thermostat housing with the rubber ring too.  The one in there came with the car and knowing the person I bought the car from, I'm sure it was cheap.  Little by little, I've had to replace most of the cheap parts he installed.  :-(

Hey Larry T,

I had the exact problem on my '79. The el cheapo chrome thermo. housing I put on the edelbrock aluminum intake leaked like crazy.

I finally had good luck with a polished aluminum thermo. housing from Spectre Industries. It is a 2 piece unit with the rubber ring.  No problems with it at all and it's been on for well over a year.

HTH,

Kevin

KDADDY792011-08-14 08:20:46

I ordered a high quality thermostat housing with O-ring and I'm now just waiting for it to arrive.  Thanks for the feedback.

Bringing back this post for an additional question.

Most likely, yes...depending on where the housing was leaking. If it leaks from the front edge, coolant may only run down the front of the engine block, toward the timing cover. In that case, you might never see any liquid coolant at all...it might evaporate before it dripped to the ground.