ARP Head studs leaking

[Mikey von]

Not wanting to hi-jack the other thread

I am planning on running head studs on my build and have only heard good things about them. In a recent thread a couple of members wrote about a problem with ARP head studs leaking.

I would like to discuss the issue of ARP head studs leaking.

What are the issues?

Fixes? GM Cadillac Tabs?

How common is this?

thanks

[More Power]

Just my opinion... The factory style TTY (Torque To Yield) head bolts are better than some might think, and could be the best choice for most people. Head gasket problems that long time owners of these engine may have experienced are more often that not due to head gasket design (early style) or inadequate preparation/assembly during a head gasket replacement. New TTY bolts are a lot less expensive than studs and you don't have to worry about leaks.

So, use new TTY Fel-Pro head bolts, Fel-Pro head gaskets, ensure the block and head decks are true and properly prepped, use the correct assembly procedure, and you'll not likely experience another head gasket problem on that engine. This is what we used on our 6.5TD Project engine, and it didn't experience a problem (of any kind) for the 250,000 miles we ran it.

Jim

[john8662]

For me, and others I've talked to (including a few engine builders) the head studs have caused nothing but grief in these engines as far as the possibility of leaking coolant into the oil, or compromising the gaskets integrity due to a leak, or the sealant used.

I've called and spoken to ARP a few times about this, and their responce was to use their own special sealant. After using their sealant and getting several more leaks on a freshly installed head (bolt holes cleaned to condition of new) I called again. The next time I called I was informed that I should use RTV to seal the studs, that there just wasn't a sure way of sealing them sometimes. Of course, using RTV is only good if you completly re-do the head job, because you need to remove the heads to tap the bolt holes to remove the previous sealant, great...

I've heard and read (RJ's engine build article) that using Lock-Tite thread sealer as both a locker and thread sealant could and should seal the head studs. I've hear of no other engine builders that have used thread locker as a sealant, nor having any success in doing so. I also haven't heard of any leaks associated with this technique, but I also doubt that we would hear of such leaks for other reaons. I would truely like to hear some feedback on that before even attempting that, but it seems logical that it could work. See, the threads on the studs and the receiving threads in the block make a very tight connection, leaving very little room for sealant to reside. If you take a stud and apply sealant to it and simply screw it into the block with no head in place, then remove the stud again, you'll see how terribly little sealant actually stays on the stud's threads and how much squeezes out. For a sealant to work in this application it would HAVE to be thin enough to thourally stay on the threads while being inserted. I for one am tired to taking the risk, and will only run the studs in one engine only, the others (up to 325HP) will get bolts 100% of the time.

That's totally not worth it to me, it simply too much work to remove the intake, lines, valve covers, rocker arms and pushrods then resealing studs to take the risk. This is what you'll find when you have a leak.



As you can see, the coolant comes up the stud, then exits through the threads in between itself and the nut, which there isn't a good way to seal. The threads on the top part of the stud get the moly lube, for torque characteristics, so a sealant here is hard to account for torque wise.

I'm with More Power in that the TTY bolts are much better than some give them credit for. They were properly engineered for sealing characteristics, using a very good dry sealant on the threads and underneath the bolt head to ensure a seal.

With all the things MP mentioned above, as far as proper preparation for the head, the head needs to be true, really true and flat, same goes for the deck. Some minor inperfections are ok, as the gasket has a sealant on it to account for this, but it still must be flat to anchor the gasket in beteen the head and the block properly. Besides, the gasket is still the weak link, take that from someone who's blown a few racing, they ALWAYS fail in the same spot, and end port, head studs simply won't fix this problem. But, this isssue is ONLY and issue when you're making 350-400+ crank HP.

My .02 that you can take to the bank