pmathews

My cheap thermostat failed after 9 months, fortunately stuck in the open position. I heard a recommendation from a fellow board member about replacing the bolts with studs, and I thought I would give it a try. Very happy with the results. No more leaking

pmathews

studs cost about $1.10 each.

m371961

Stainless?

jpc647

Your housing was leaking too?

This is probably a dumb question, but how do studs, as opposed to bolts make any difference? Assuming the bolts you took out were old, wouldn't new, quality bolts do the same?

I just try and shy away from studs, they've always been a hassle for me.

MDchanic

I just always replace the original bolts (screws, actually) with stainless.

Unless the studs you install are stainless, you'll have trouble again sooner or later.

- Eric

pmathews

For those that aren't familiar, the bolts thread into the water passage, so water can leak past the threads and cause a slow dribble that pools on your intake manifold, even with generous amounts of rtv.

I used red thread sealer on the studs that enter the water passage to prevent any leaks via the threads.

I'll switch to stainless studs during the next thermostat swap.

pmathews

New bolts would definitely help, but my manifold is 47 years old, and the female threads in the manifold are worn. I could retap and use a larger bolt, but using studs and thread sealer are much easier, at least for now.

m371961

I like red loctite on stainless studs. Then you only deal with the stainless nuts to remove the housing and never disturb the threads in the manifold. If the threads in the manifold are bad, install a heli-coil and stainless studs with red loctite. If you drill the manifold to a larger size you have to drill the thermo housing and the larger bolt head may not clear.
Studs, IMHO, are easy to deal with if stainless is used. Even if the nut strips or rounds, you split the nut and reuse the stud.

oldcutlass

I like the studs and the fine threads tend to work a lot better.

jag1886

It's been proven that a bolt will seal better that a stud in a water passage, just ask the Mopar guys that have water leaking out of there exhaust manifold.

61reoldsman

I had leaks with my thermostat housing so I ran the outlet housing over a belt sander a few times to get it perfectly flat , put it back on with a metal reinforced gasket and , voila ! no more leaks .

KDV

Having this same problem at the moment.

Where'd you get your gaskets?

61reoldsman

Inline Tube

RandyS

Huh? Is there a differnce in mechanical force applied to a surface between a bolt or a nut?

m371961

I know about the mopar. Stud, helicoil and red loctite cured that one for me.

olds 307 and 403

Flatness is important for sure. I had seepage issues till I used double gaskets and RTV. Even my Robmc water neck seeped till I used 2 gaskets and sealant on the threads.

KDV

Thanks! Found them on Ebay

68-72 Water Neck/Thermostat Gasket

pmathews

Regarding the earlier comment about bolts being better, I must be missing something: studs and bolts have identical threads, so it's not making sense that bolts are better. Please correct me if I'm wrong, but they should perform identically with regards to jacket sealing?

Maybe mopar studs are made with inferior material (haha). Seriously, stainless bolts would do better than non-stainless studs, but I think there's something missing in the mopar story.

One benefit of studs over bolts, when you re-tighten bolts, you break the loctite seal. With studs, you tighten the nut and the loctite stays intact.

For those that have good threads in the manifold, this conversation probably sounds silly, a good gasket seal should work, but for older manifolds, the threads can corrode a little, making the bolt engagement imperfect, causing a little seepage.

m371961

Mopar SB has a exhaust manifold bolt that goes in the water jacket. I had a set of heads done that the manifold bolt had broken off inside it. I had them remove it. Installed it with a bolt and it leaked. Removed header and installed heli-coil, SS stud both with red loctite. Ran it for years. Most likely threads were bad, but not stripped.
(Sorry for the Mopar story)

61reoldsman

Great ! just make sure all your surfaces are good and clean .