head studs and coolant leaks

[MikeB]

Just remembered this after reading a post here about using head studs instead of bolts to reduce cylinder distortion.

The one time I tried to use head studs on a small block Chevy, I ended up with coolant leaks under a few nuts/washers; even with clean threads, ARP studs, and ARP sealant/lubricant. Not sure if I'll ever use studs again, but what's the best way to prevent leaks, other than using a block with blind holes? The block was freshly bored and decked. Problem was resolved by using ARP head bolts.

[mag2555]

First off was the block bored with a deck plate and the studs, if so and your running it with bolts now , then your Bores Are no longer round.
When I have used studs in any non blind hole block I use permatex blue gasket maker and have never had a issue as long as both the stud threads and the bolt holes where free from oil and I allow the sealer to set up over night.

I one time had a tube of ARP lube/ sealer to use with the first set of head studs I was every going to use,but I never used it after I asked my self how the Hell will a sealer that is also a lube really going to seal things up, and with anyway you do not lube on the block end of the stud!

[wyrmrider]

Hylomar

[statsystems]

That's why I never used studs with out having blind holes.

I got tired of guys bitching about getting them sealed. So I just either used good bolts or let them put it together and see if the customer could seal them.

[MikeB]

That was more than 15 years ago, but I'm pretty sure it was plate honed using torqued bolts. So, it's a good thing I had leaks!

[DaveMcLain]

This is a common problem with studs especially in production block Chevrolet engines. Right now I'm freshening up a 434 that I built about eight years ago for a customer with a jet boat. He had me use ARP studs on the build and I remember and I can see where I put silicone on a few that wanted to drip when the engine was on the dyno. All was well and everything looked fine when I took it apart. I'm thinking of screwing them back in using some pipe thread compound on the block end when I put it back together. Remember that with studs you screw them in by hand till they stop and then back them out a turn or two so they are not bottomed in the hole which can cause cracking.

[groberts101]

Some here appear to be saying that if you're having issues sealing a superior fastening product then it's best to move back to an inferior fastening product?

Sorry, not buying it in the least. I would normally just decide to figure out how to seal the threads for a specific application like so many others who've been, and still do, successfully running head studs in OEM iron have over the last 50 years. Threads into block/water need dedicated sealant NOT lube. Fix the cause of failure.. not diminish the parts performance value.

I would also point out that using any hardening type sealant or resinous loctite product would be a no-go for myself due to the fact that it can and does add too much variable to achieving and maintaining consistent and long term torque spec's. Plus, you then need to get the head/s on and clamped down to final torque spec' before it dries(which is even quicker when the iron is warm). I know many pro's who still do it and seem to not have issues but it's a friggin' mess to clean up if you're just doing the top end.

A couple of thread sealants I and many others have successfully used in the past.

Permatex Hi-Temp thread sealant
Hylomar(this shit's tougher than superman)

Worst case scenario?.. buy a block/head sealer which contains liquid glass(sodium silicate) to seal up smaller nuisance leaks like this. Again, fix the cause of failure(leaking threads).. not diminish the parts overall performance value by downgrading to bolts simply because they have more interference fit with the block. And we all know that bolts can still leak on occasion too.

[nhrastocker]

I use either Loctite/Permatex 1158514 Head Bolt and Water Jacket Sealant or Permatex Aviation Form-A Gasket Sealant Liquid 3D, Part Number 80017.
Never had a leak.

[Newold1]

I'm with groberts101 on this one.
Have good clean stud threads going into good cleaned block threads, use a good non hardening sealant and they should not leak!
The problem if incurred is with the installation , not the product or system here.

[pdq67]

Good old, "Indianhead Shellac Gasket Cement"!

A, "messy", daub on the stud's block threads and when you install the heads, put another one under each washer and nut!

Indianhead was made for this stuff, BUT it is way, "Old-School"!!

I also use it with shim head gaskets by re-torqueing them about three times over three hot and cold cycles DD her fine!! But again, darn stuff is messy!

pdq67

[Keith Morganstein]

Yep, the old brown Permatex will seal them. (Brown paste in the tube, or Indian head, etc...)

[rfoll]

The threads, (both stud and block), need to be free of water or oil for any of the suggested sealants to work. That alone is likely to be more important than the product used.

[superpursuit]

I have always used GM Sealer and have never had a problem with leaking. Threads need to be clean as already mentioned. The GM Sealer is now sold under the AC Delco banner. This stuff is made by GM for this exact purpose.

[KnightEngines]

^ what this guy said, that's all I ever use, a good portion of the engines I build have bolt holes through to coolant & use ARP studs.
I don't get leaks.

[Tuner]

An ounce or two of Sodium Silicate (Water Glass) in the coolant is all it takes. $20 buys a nearly lifetime supply.


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