I need opinions on sealing head bolt threads - Chevelle Tech
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post #1 of 26 (permalink) Old Jan 27th, 11, 5:43 PM Thread Starter
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Tom
 
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I need opinions on sealing head bolt threads

For MANY years I've used Permatex Liquid Teflon (in the plastic jar) to seal the threads of head bolts. I simply stuck the threads into the jar then immediately inserted the bolt through the head and screwed it into the block.

Well, today I picked up the 383 from the machine shop that is going in the 51 Chevy.
They told me to use RTV on the head bolt threads. I told them I've always used the liquid teflon. They said use the RTV. I asked WHICH RTV, Ultra copper, black, blue, which? They said it didn't matter, just use the RTV instead of the liquid teflon (which I've been using for at least 30yrs per recommendation of a previous machine shop).

So, from the professional engine shops, what's your recommendation for sealing head bolts???

Tom Parsons
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post #2 of 26 (permalink) Old Jan 27th, 11, 5:51 PM
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Re: I need opinions on sealing head bolt threads

I am not in a pro shop, but I did work on engine sealing and fasteners in Chrysler engineering. We (and Chevrolet) used Loctite Pipe Sealant with Teflon very successfully. RTV has a habit of making globs that go into places where they are not welcome.
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post #3 of 26 (permalink) Old Jan 27th, 11, 6:04 PM
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Re: I need opinions on sealing head bolt threads

I use RTV myself. Any of the Ultra versions. I smear it into threads in the holes in the block. Most any thick type sealer ends up in a pile around the bolt if you put it on the bolt threads. I think you'd be OK with the teflon pipe dope though.

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post #4 of 26 (permalink) Old Jan 27th, 11, 8:43 PM
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Re: I need opinions on sealing head bolt threads

Wether you place the sealing compound on the male or female threads makes no difference. If it is on the bolt the majority will end up being pushed off at the top, the rest will seal inside. Conversely if you put it on the bolt hole, it will be pushed off to the bottom of the hole filling the rest to create the seal. I always put the RTV or Thread Selant in the threads, making sure I remove the excess before I put it into the hole. The point of the sealant is to take up the remainder of the space between the threads as there is between 60-80% interfereance.

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post #5 of 26 (permalink) Old Jan 27th, 11, 9:31 PM
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Re: I need opinions on sealing head bolt threads

The Permatex i have used on head bolts, says its a gasket sealant. but in the applications it lists Freeze Plugs. and Threaded Connections. I have used it many times and never a leak.

Permatex #1: http://www.permatex.com/products/Aut..._1_Sealant.htm


They also have a sealant specific for threads: http://www.permatex.com/products/Aut...ad_Sealant.htm

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post #6 of 26 (permalink) Old Jan 27th, 11, 9:42 PM
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Re: I need opinions on sealing head bolt threads

I've used Gray Ultra on my last two motors (as per a local builder) with no problems.
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post #7 of 26 (permalink) Old Jan 27th, 11, 10:38 PM
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Re: I need opinions on sealing head bolt threads

Since the advent of Loctite's PST, we never used teflon tape again. I worked at GM and in the bodyshop all the weldgun arms are water cooled with a gadzillion fittings. I still use it on every fitting I install at home and have never had a leak. I used it on the 455 Pontiac engine that I assembled a few years ago and it worked fine too. I've just had no reason to use anything else.
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post #8 of 26 (permalink) Old Jan 27th, 11, 10:49 PM
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Re: I need opinions on sealing head bolt threads

Old school inmdian head shellack work just fine for sealing head bolts or any bolts that need to seal off coolant and or oil.

I have also used ARP's white teflon thread sealant with good results last time i rblt my 396 in 2001/7k miles ago .

Buti have read here in t/c where others had coolant leaks using teflon paste.

But i have a feeling that may happen if the threads in the block and or on the bolts aren't cleaned properly with a solvent like brakleen/carb cleaner etc to remove all oil/grease/maching oil etc prior to reassembly.

Scott

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post #9 of 26 (permalink) Old Jan 27th, 11, 11:07 PM
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Re: I need opinions on sealing head bolt threads

Permatex #2
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post #10 of 26 (permalink) Old Jan 27th, 11, 11:17 PM
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Re: I need opinions on sealing head bolt threads

Quote:
Originally Posted by jj'65 View Post
permatex #2
x2

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post #11 of 26 (permalink) Old Jan 28th, 11, 1:45 AM
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Re: I need opinions on sealing head bolt threads

Quote:
Originally Posted by 77 cruiser View Post
x2
Permatex #2, or Aviation Gasket bottle & brush.

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post #12 of 26 (permalink) Old Jan 28th, 11, 2:07 AM
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Re: I need opinions on sealing head bolt threads

Quote:
Originally Posted by Keith Tedford View Post
Since the advent of Loctite's PST, we never used teflon tape again. I worked at GM and in the bodyshop all the weldgun arms are water cooled with a gadzillion fittings. I still use it on every fitting I install at home and have never had a leak. I used it on the 455 Pontiac engine that I assembled a few years ago and it worked fine too. I've just had no reason to use anything else.
PST is a miracle sealer. I've used 567 and 592, both work extremely well. Truth is, I can't tell the difference between them. However, the 592 is SPECIFICALLY RECOMMENDED for head bolts in through-holes.

http://www.hrpworld.com/index.cfm?fo...action=product
Loctite PST Thread Sealant 592
Loctite® 592 PST® locks and seals threaded fittings.

* Resists leakage, vibration loosening, moisture, hydraulic fluids, and diesel fuels.
* Lubricates threads for easy assembly and disassembly.
* Won't shred or wear like Teflon® tape.
* Parts may be repositioned up to 24 hours after application.
* Works to 400°F.

Suggested Applications: Head bolts into through holes, oil psi sending units and sensors, oil and coolant lines, fuel fittings, rear axle fill plug, brake and power steering fittings.
How do you re-torque head bolts that have been gooped up with RTV? The RTV sets up, you re-torque--and break the seal.

Conversely, Loctite 592 is advertised that you can re-position the fittings for 24 hours after application. Exactly what's needed for re-torquing bolts.

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post #13 of 26 (permalink) Old Jan 28th, 11, 8:57 AM Thread Starter
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Re: I need opinions on sealing head bolt threads

Thanks to everyone for input.
It looks like there are multiple choices and all of them seem to be acceptable.

Tom Parsons
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post #14 of 26 (permalink) Old Jan 28th, 11, 9:16 AM
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Re: I need opinions on sealing head bolt threads

I used Permatex #2 on a 95 Chevy small block pickup a couple of weeks ago.
Wasn't there to supervise when my granddaughter's man put the heads on and didn't use anything on them. I figured out that I could do them one at a time without loosening the valves I had already adjusted because the 4 top bolts do not go into the water jacket.

We started it up yesterday and I had a bunch of valves way out of adjustment I guess I got screwed up following the book and had the crank rotated wrong.
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post #15 of 26 (permalink) Old Jan 28th, 11, 9:30 AM
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Re: I need opinions on sealing head bolt threads

I am hardly an professional engine builder but I am an ASE Master Tech. When I got into using nitrous on my cars 20 years ago I didcovered Teflon Paste. Been using it on all my Chevy builds ever since and never had a seepage issue with it. I think either one will work, so it really comes down to your own personal preference. But the paste comes with a brush in the lid generally. Much easier to use than silicone,IMHO.

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