Head studs are notorious for leaking water. All you can do is reseal each of the studs individually that are leaking, until they stop. You don't need to remove the heads to do this... Just pull out the studs one at a time, put sealant on the threads, then put it back together.


Chuck

 

So basically it sounds like head studs are not a good idea for a daily driver street/racecar...only someone that will be removing the heads often?

 

Well once they seal you're fine. But yeah, for an average street car, I would stick to head bolts.


Chuck

 

Here are a couple naïve questions. If head studs are so problematic, what good are they? Why not just use a reusable head bolt like the kind ARP makes? Can they really be more robust in high-power motors if they chronically leak water?

 

Nobody said they "chronically leak water". They just have a tendency to not seal at first. Once they seal you're fine, and often they seal on their own from the impurities in the water.

Chuck

 

Go with bolts unless you need more clamping force than you can get with the pro series arp bolts, which is unlikely unless you are running copper head gaskets.

The head of the bolts acts as a mechanical seal which is much better than using sealer.


John Carpico

 

Always use studs over bolts when you can. I've run head studs for 3 years with no problems(done head gaskets about 3 times). When assembling with head studs alway use high temp orange RTV.Other stuff tends to melt off from the heat. Just coat the treads going into the block with the orange rtv. Use moly lube on the top threads. All studs must be torqued after the rtv is applied. If you do this your studs will never leak

 

Anyone think this leakage issue may be due to insufficient "cure" time for the sealant? Looking at the sealant (from Permatex at least) it seems like it'd take a fair bit of time to have it set up right.


Is there a recomendation on cure times before filling the heads/block with coolant?

 

Last dumb question:

Anyone think this issue may be indicative of poor thread engaugement? Not on the part of ARP's, but of general block tolerances and the imperfections created by the original head bolts GM used?

Doesn't ARP reccomend that studs/bolts be fully installed/torqued and removed 5 times before the final set up? Maybe conditioning the threads has more to do with this than pre-stressing the shaft.

Hmmm... interesting topic.

 

Cure time, read the directions on the back of the rtv. I have always waited a day before installing water. I think the main issue here is as stated, the type of thread sealer used. The orange is great; I've used it on headers, water pumps, studs, etc...never any problems

 

I agree it's the sealer, I used arp sealer the first two times and it leaked I think arp is meant to act as a lube and a sealer so it makes sense its harder to do two things well. The permatex I think is more like locktite as it sets up in absence of oxygen.

No leaks yet and I still have my fingers crossed.

John Carpico

 

I have had no problems with head studs leaking. I use ARP thread sealant.

Also, I see no reason to use copper gaskets period. Use cometic gaskets.. they are nearly industructable :-D