Thermostat gasket.

flipper35 · #1 (**permalink**) 12-09-2003, 12:33 PM

Gasket was fine for years, then all the sudden it started spraying all over the place. Replaced it with an OEM 2x, once with Permatex and once without. Then I see the OEM doesn't fit very well, with only about 1/8" of the actual gasket sandwiched between the manifold and houseing. Took the old gasket and found one with the same bolt holes and same I.D. but a larger surface area and cleaned the surfaces again, torqued to 200 in/#. The gasket is not leaking, but it is wet after getting up to temp. So now what?

Ron61 · #2 (**permalink**) 12-09-2003, 12:54 PM

Brent,

I don't know if this will help, but about 4 years ago I had a similiar problem and kept getting just a little drop or so of water out after driving and two gasket changes later decided I needed to try something else. Since my intake is aluminium I didn't dare try and tighten it past the specs very far, so I went to NAPA and got some good thick gasket material and made a gasket. After getting it all cut and some putting on a little permatex, I bolted it back on and have never had a seep since then. I made sure the gasket I cut covered the whole area of the intake and housing. I don't know if it was the thicker gasket material and permatex or if I just got lucky. I won't pull it off to look unless it should ever start again.

Ron

flipper35 · #3 (**permalink**) 12-09-2003, 01:38 PM

Thanks, I'll try that

Brent

Mr.Fixit · #4 (**permalink**) 12-09-2003, 02:13 PM

Do you have one of those nifty chromed thermostat housings? If you do, hold it against a straight edge and see how warped the gasket sealing surface is.

I usually smear a light coating of clear silicone RTV on paper gaskets that seal in water (thermostat, waterpump)

flipper35 · #5 (**permalink**) 12-09-2003, 03:28 PM

It is a stainless unit. Replaced the original warped aluminum one with this nice thick piece. I have a roll of thick gasket stuff and some RTV. My intake is AL too, so I didn't wan't to over torque anything. Thanks guys.

Rick Parker · #6 (**permalink**) 12-10-2003, 10:37 AM

There has to be a "relief step" machined in either the manifold or the thermostat housing to allow the outer diameter of the thermostat to seat as it is sandwiched between the manifold and housing. Some combinations do not have this. Without the step you may experience this type of leak. There are 2 or 3 different gaskets for this application. Some have a larger bypass hole reducing the amount of gasket material that actually forms the seal.

Just a thought...............

Rick

hound dog · #7 (**permalink**) 12-10-2003, 10:46 AM

Yep, been there done that. Had a chrome thermostat housing and it was warped far beyond any manufacturers spec! Was surprised to find that the mating surface on the Edelbrock intake wasn't flat either. What a mess! Anyway, I took a large file and went to work on the thermostat housing and got it reasonably flat and reassembled with plenty of silicon sealant on both sides of the gasket and haven't had a problem since. Double check your sealing surfaces.
h dog

flipper35 · #8 (**permalink**) 12-10-2003, 11:03 AM

The relief is in the t-stat housing, and when I put it on I made sure the t-stat was centered and in the relief before I tightened it down. Funny thing, this had been fine for years before the original let loose. I am going to use silicon with the same size gasket. Should solve the problem. I am going to check the surfaces with a small straight edge while it is apart too.

Thanks guys.

Rick Parker · #9 (**permalink**) 12-10-2003, 11:58 AM

IS THIS FOR A MOPAR???!!!!!

Cobra20646 · #10 (**permalink**) 12-10-2003, 12:19 PM

Are you putting a thread sealer on the threads? The bolts go all the way through into the manifold, and any leak will look like a gasket leak to the casual observer.

- Jim -

flipper35 · #11 (**permalink**) 12-10-2003, 12:31 PM

The gasket goes around the bolt holes too so I didn't put any thread sealant on.

Cobra20646 · #12 (**permalink**) 12-10-2003, 01:04 PM

Brent,

I know..... and I had the same problem, and that was my fix. Coolant leaks past the threads, follows the bolt past the gasket, exits at the head of the bolt, and a tiny drip appears at the bottom of the thermostat housing.... looks like a gasket problem, but.......

I guess if you globbed enough rtv or permatex on both surfaces of the gasket, some would get squeezed out and along the bolt to seal it, but putting some on the threads first will get it right the first time.

- Jim -

Ron61 · #13 (**permalink**) 12-10-2003, 01:29 PM

Brent,

Jim is correct about the thread sealer. I forgot to mention that in my post but I used it on mine and haven't had a seep for years. Now that I have said this it will probably blow water everywhere the next time I start it.

Ron

flipper35 · #14 (**permalink**) 12-10-2003, 02:10 PM

Ain't that the way it goes. Now that the weather has cooled and it is more enjoyable to drive, I get to work on it. I guess it is just a little thing though, I could be replaceing an internal component or something.

flipper35 · #15 (**permalink**) 12-29-2003, 01:16 PM

Well fellas, the bolts holes don't go into the water passage, hence the problem. The bolts bottomed out in the holes. How I missed that and how the original sealed I'll never know. Two small washers, some Permatex and all is well.

Rick, yep it's for a little tiny Mopar block. Have no worries though. There is a seasoned block in front of the lift just begging to be built and put into the Cobra. It will be a little bigger tiny Mopar. Can't complain, the 400 or so ponies will never make the a833 ever break a sweat. The new 485hp might tickle it a bit, but I won't ever have to worry about the tranny.