Sealing up the thermostat housing studs

I'm kind of stumped on this one.

When I warm my car up, there's always a little coolant that seeps out through the thermostat housing studs. The gasket itself is fine, doesn't leak at all (have all three nuts torqued equally so I'm good on that front).

It's a little pain in the butt...stuff sprays everywhere and is ruining my brand new paint job on my engine! That antifreeze will NOT come off of there for the life of me!

Was thinking I'd remove the studs and put some silicone on each of the threads, but I was also thinking maybe there's a more proper way?

Feel stupid for asking such a simple question...but I am a bit sleepy this morning...can't figure this one out.

Any experts have any advice?

No sealant on mine and no leaks. Reassess the gasket and make one yourself if you've got the materials at hand. Gasket kits can usually be had at the local car shop.

Blue loctite should seal that up. For the life of me I can't remember what I used on mine, but they don't leak...and loctite it what I usually use on stuff like that, so I probably did it automatically!

I would question the gasket before sealing the studs. Coolant should probably not reach the studs in the first place.

But those studs go directly into an area where there is plenty of coolant flowing around, even if the area around the studs is perfectly sealed, there's still a little coolant that can seep up through those threads, amirite?

Might just try a new gasket for good measure, I have plenty of gasket material and also a gasket punch/various cutting tools.

you are right, I forgot that the studs go down into the little housing area and are subject to getting wet on the bottom. The lock tight down there is probably a really good idea. Mine are pretty well cast in place, no leakage. If they were new, I can see some potential for leakage.

You can buy teflon thread sealer. Permatex makes it for one. Silicone or the locktight would probably work but there is a specific product.

I had a leaker on the TR8 new engine. One of the front cover bolts went into the water jacket. Put that stuff on and took care of it.

Studs into jacket can be sealed with a number of products. I like Permatex Form-a-gasket #2.

Royal,

You're correct. Two of those studs thread directly into the water jacket. However I would caution you to not remove them unless they are fairly loose. The threads in the head tend to corrode from the coolant, and if you remove them you run the risk of loosening even more of the metal in the threads in the head. And if these threads become unserviceable, Heli-Coils are not a good repair because of the additional set of threads that could serve as pathways for coolant.

I suggest using the Moss upgraded gasket, as the cork and thin paper gaskets are pretty much useless, and I also suggest a thin ring of Permatex around the studs both below and above the gasket, which should keep the coolant from wicking up through the threads.

Dick

I use teflon/ptfe pipe tape on mine. couple layers of that on brand new tapped threads with new studs and no leaks!

I also use it on the manifold studs that go in to the oil channels. Not ran car much so don't know if that stopped that leak or not!

This is a common point of leakage. As others have observed, one (or two ?) of the studs go into the area that has the coolant. Loctite and others make actual thread sealant. Remove the stud, clean the area up, apply a few drops of the thread sealant and that should do it.

The annoying thing is that you have to drain some coolant or else you are working with wet components. Some of the thread sealers seem okay with that, but they usually recommend doing it dry.

The one thing not covered here is the destruction of your engine's new paint job. Moss paint? Next go-around, try duplicolor dark canyon red.

I actually use Anti-Seize on the studs where they go into the head. This way they won't corrode and seize up. It also seems to seal the threads against coolant leakage. Also, removing the thermostat housing becomes a very easy job. RAY

Locktite would create an even bigger problem trying to remove them later, I should think. Corrosion is bad enough!

Use stainless steel 304 alloy set screws 1-3/4" long. Use a little teflon pipe compound or teflon tape on the threads--or even a little RTV. An advantage of the set screw (apart from corrosion resistance) is that you can also re-tighten the stud itself if it should loosen or back off due to gasket compression (I've seen that on one stud--no, you do not want to bottom the stud!). And don't use a cork gasket...thick paper, not the thin stuff.

The studs are brand new, I took the liberty to replace them when the engine was out for the clutch job. I wanted to put a 180 thermostat in there, and in doing that, I had to actually heat up the cylinder head to get the old studs out. I also needed to get a new thermostat housing because someone at one point used a screwdriver to try prying the housing up.

The uprated Moss gasket is great, it's what I'm using. No leaks except for the few drips from those studs/nuts.

I always grease the gasket and the bottom of the housing for easy removal, and I think my plan is to silicone the studs that go into the head and grease the nuts, and see if that works.

Thanks guys!

Is 1-1/2" too short Mac/Hap - I'm wondering if that 1/4" extra 'grab' makes a huge difference?

I've used RTV to solve this in the past. Just enough to coat the threads before installing the studs.

You definitely want something to help prevent the studs rusting themselves into the head. Next time I'll probably try Loctite 518 anaerobic sealant.

1/2 the battle is making sure the studs are firmly tightened into the head in the first place as where the thread runs out it tends to form a conical seal against it. A bit of thread tape should be all that is required to make that 100%.

It's a poor design though whichever way you look at it, as those who have experience of cars where the housing may not have been off for many years know too well.

I just use the studs as intended but liberally coat them in copper grease.

I had the same issue... I found that over the years of old gaskets, they'd accumulated pieces and parts around in and around thermo seat and surface where the gaskets sat... A scrapper, one of my kids balloons inflated to keep debris out of the coolant pool, and elbow grease removed all the caked on stuff... It was A LOT!!!

No leaks at all any more... Not saying this is your issues, but it may be worth checking out...
:)-D