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Re-Sealing End Header Bolt 440 Iron Heads - Any Tricks?

PurpleBeeper

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I have an iron head 440 I built many years ago in my car now. I have exhaust manifold studs except for two holes which I installed header bolts (driver front bolt/passenger back bolt).

About 2 weeks ago I started getting a little drip from the passenger/back header bolt. fyi- I don't seem to have an exhaust leak. Anyway, I drained the coolant, removed the bolt, smeared it with RTV silicone....still leaked. I bought a longer bolt, cleaned/dried everything, squirted silicone inside the hole & smeared it on the bolt.....still leaking. I did verify that it's coming from that pass/back bolt area & NOT from the corner of the head (thank God).

Ok, before I do this for the 3rd time, does anyone have any good tips how to make sure it gets sealed this time? THANK YOU!
 
Teflon tape is wonderful for thread sealing. It doesn’t go anywhere. It’s better than Teflon paste, which over time can migrate away from where you want it.

RTV is not really for sealing threads, but it can work. Clean it all out of the hole first with brake clean or carb cleaner and a tap.

How long does the header bolt go into the threads? Sometimes they are shorter. You could get a longer 3/8” bolt to use if they are short.

Hate to mention it but you could possibly have other problems, but do the Teflon tape first.
 
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Why are there bolts? Was a broken stud removed and heli coiled? It will not seal with the heli-coil. A better repair would be a Timesert, blind or thru hole. The solid insert, sealed with red Loctite will seal the circumference a hell of a lot better than a heli-coil. RTV should never be used on bolts for threads, as it just doesn't work correctly. A great thread sealer is ARP 100-9904. It is a Teflon based paste sealer designed to be used on threads.
 
The leaking header bolt was pretty short, so I did try a longer bolt my 2nd attempt. I seem to recall that I did have some nickel-sized inserts put into heads, but I don't remember if it's on the holes with the bolts (seems likely).

I've had success with RTV silicone on this motor for the 2 bolts for many years & the other head is still sealed....but Teflon paste seems like a reasonable thing to try. I may go ahead and pull the header off the passenger side to make sure everything is clean/dry.

Any other ideas or tips guys?
 
Thanks guys! OK, here's a "what if". The more I think about it, I think there's a good chance that one of those "nickel-sized black thread inserts" is in the location where I have the leaking header bolt. I will know for sure when I pull off the header.

Now, if it's there, what should I do? I mean, it "could" be leaking around where that insert is in the head. Should I try to remove/re-seal/replace that insert? If yes, then how do I do that? (a shop put those in YEARS ago).
 
All the rust in my engine block worked for me ha ha. But seriously now I wonder if mine will start leaking again, it sealed when I brought it up to temp after I put headers on.
 
Clean threads well.

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Thanks guys! OK, here's a "what if". The more I think about it, I think there's a good chance that one of those "nickel-sized black thread inserts" is in the location where I have the leaking header bolt. I will know for sure when I pull off the header.

Now, if it's there, what should I do? I mean, it "could" be leaking around where that insert is in the head. Should I try to remove/re-seal/replace that insert? If yes, then how do I do that? (a shop put those in YEARS ago).
I like to put a stud in the front and rear header bolt holes. That holds the header and gasket in place while you start the other bolts. That also seals better than a bolt. And wrap a few turns of teflon tape around the stud, or wait a few years for rust to seal it. Haha.
 
Beeper,
Had the same problem. I first tried ARP thread sealant. That was successful on a
couple of the bolts, but the end two I couldn't get to stop leaking. I used Permatex
#2 next and that worked. I agree with the post that encourages cleaning of the threads in the head.I cleaned mine several times before the Permatex.
Good luck. RR.
 
Teflon tape is a better choice than the paste.
I build motors for a living, and I haven't used tape in a long time. I use the ARP Teflon thread sealant, and have NEVER had a leak yet. It is by far a better product than the tape, period.
 
Thanks guys! OK, here's a "what if". The more I think about it, I think there's a good chance that one of those "nickel-sized black thread inserts" is in the location where I have the leaking header bolt. I will know for sure when I pull off the header.

Now, if it's there, what should I do? I mean, it "could" be leaking around where that insert is in the head. Should I try to remove/re-seal/replace that insert? If yes, then how do I do that? (a shop put those in YEARS ago).
If an insert was used, and leaking, it probably wasn't installed very well. You will have to drill it out carefully to loosen the swedged end at the bottom. Try not to destroy the threads so you can install a new one. If the hole in the head is too big, you can go to a Timesert "Bigsert". It is your last chance to fix it properly.
 
Rector Seal, get it at the plumbing supply. For high pressure steam fittings etc. , non hardening. And don't use it for regular gasks.:thumbsup:
 
I build motors for a living, and I haven't used tape in a long time. I use the ARP Teflon thread sealant, and have NEVER had a leak yet. It is by far a better product than the tape, period.
I haven't used anything but PST 592 in 20 years. Not a single leak, whether it be water, fuel or hydraulic. I don't own a roll of tape..
 
I've always used the Permatex "blue" for exhaust studs, never had issues except for one rather wallowed out hole once.
For that, I reverted to my lifelong profession (fire sprinklers) and whipped out the Teflon tape + what we call "Rectum Seal" (Rector Seal).
If you can't get a thread leak to seal with that stuff, it's time for some machine shop attention. We call it that for a reason. :)
 
Napa sells a small 1/2 pt. can of thread sealer , its for hyd lines, steam , non drink water , fuels, ect.
It is a lead base sealer. If you have good threads it will seal it.
 
Agree with the post, should be/have studs installed on the front and rear holes. These go into water jackets.
 
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