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ARP Head studs leaking

Mikey von

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I am planning on running head studs on my build and have only heard good things about them. In a recent thread on another board 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
 
Leaking? I've installed two sets, run 'em under heavy loads and with lots of boost, never had an issue.

Only thing I can think of is that the bolts run into the water chamber in the block, requiring thread sealer. Stock head bolts come with thread sealer on them, you need to put thread sealer on the bottom end of the stud before installing. I use Permatex hi-temp thread sealer (white gooey stuff).
 
Only thing I can think of is that the bolts run into the water chamber in the block, requiring thread sealer. Stock head bolts come with thread sealer on them, you need to put thread sealer on the bottom end of the stud before installing. I use Permatex hi-temp thread sealer (white gooey stuff).

+2 The water jacket issue is the only one I have ever heard of. Some have recommended periodically checking the torque on the head bolts since they are not TTY like the factory bolts but with the number of people running them I dont see it as a major problem. Make sure you seal the threads and you shouldnt have issues. What was the problem on the other board?
 
just found out you have to be registered to see the posts.

here is the main response I got in the thread I started;

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.

P10100012.jpg


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 ;)
 
On the original thread where it was mentioned - this same guy john brought it up and then the owner of Kennedy Diesel said he has also had problems with apr head studs leaking;

If this is a true mechanical injection truck you will want to use the proper balancer for the early mechanical engine. It has a longer "snout" to take up the extra space and capture the gear.

I too had some difficulty with leaky head studs and eventually the GM "Cadillac Tabs" were my magic bullet. It's just more critical to seal a stud than a bolt as it's just threads that you are sealing. The bolts provide an extra measure of sealing uner the rim of the head, but the coolant should not be that far.
 
Funny...I didn't seal my ARP studs at all and have had no leaks. Maybe his engine has been apart so often the threads aren't near as 'tight' as they once were? All my studs had to be driven in using an Allen socket, none went in finger tight.

Rene
 
Yeah, that's possible too. I used a standard tap to chase the threads on the first set of heads I ever did, and was disturbed enough at how loose they were afterward to never do that again. Now I just grind a flat on an old bolt and run it in and out a couple times. If the block is getting hot tanked I don't do anything with the threads. 'Course, with studs its not as big a deal because you're not reading torque off those threads . . .
 

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