I need opinions on sealing head bolt threads [Archive] - Chevelle Tech

: I need opinions on sealing head bolt threads


DZAUTO
Jan 27th, 11, 5:43 PM
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???

JWagner
Jan 27th, 11, 5:51 PM
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.

Tom Mobley
Jan 27th, 11, 6:04 PM
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.

twotone64
Jan 27th, 11, 8:43 PM
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.

chrispicide35
Jan 27th, 11, 9:31 PM
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/Automotive/automotive_gasketing/gasket_sealants/auto_Permatex_Form-A-Gasket_No_1_Sealant.htm


They also have a sealant specific for threads: http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

Yellomalibu
Jan 27th, 11, 9:42 PM
I've used Gray Ultra on my last two motors (as per a local builder) with no problems.

Keith Tedford
Jan 27th, 11, 10:38 PM
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.

SWHEATON
Jan 27th, 11, 10:49 PM
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

JJ'65
Jan 27th, 11, 11:07 PM
Permatex #2

77 cruiser
Jan 27th, 11, 11:17 PM
permatex #2

x2

TXCR13
Jan 28th, 11, 1:45 AM
x2
Permatex #2, or Aviation Gasket bottle & brush.

Schurkey
Jan 28th, 11, 2:07 AM
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?form_prod_id=2073&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.

http://www.hrpworld.com/client_images/ecommerce/client_39/products/2073_hdr.jpg

DZAUTO
Jan 28th, 11, 8:57 AM
Thanks to everyone for input.
It looks like there are multiple choices and all of them seem to be acceptable.

Dean
Jan 28th, 11, 9:16 AM
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 :o I guess I got screwed up following the book and had the crank rotated wrong. :confused:

Andy's Auto Repair
Jan 28th, 11, 9:30 AM
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.

Andy

69-CHVL
Jan 28th, 11, 9:32 AM
Use whatever you have laying around. Heck, some guys say antiseize works.

I use whatever is in my plumbing bucket...usually a white teflon paste from Homedepot.

I like the #2 Permatex, but its very hard to clean-up and is generally just nasty. I also question if it throws torque readings off as its so thick and like tar...you can feel the resistance when threading a bolt in using the stuff.

OLDED
Jan 28th, 11, 9:36 AM
Permatex #2 it and forget it. Seals great and lets you remove the bolts later - and prevents the threads from rusting out.

Tony B
Jan 28th, 11, 11:11 AM
PST (pipe sealer w/teflon), like already stated, is the way to go. My background before being an engine builder was industrial hydraulics, and that's all that is used there(on threads).TB

70-SS454
Jan 28th, 11, 5:23 PM
Permatex #2

HotWheelsFan
Jan 28th, 11, 5:50 PM
I used to use silicone, it has always worked fine for me.

But I noticed after working in the dealer for many years... And using silicone to seal water pump bolts and thermostat housing bolts, corrision would slowly build up around aluminum pieces.

Now there would not be real leakage but I felt the seal could be better. I started using permatex #2 and it has worked much better for me.

My conclusion is that it seals better, and allows for better bolt removal. Since then, I use it for head bolts and freeze plugs as well.

I'm sure there are many different favorites out there and most work just fine.

Bob

chrispicide35
Jan 28th, 11, 5:59 PM
Permatex#2 seems to be the favorite.

I know i said Permatex#1 in my post on page 1, But maybe it was Permatex#2 i cant quite remember. My engine builder said either one would work.

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.

Fel-Pro PermaTorque head gaskets. No need to re-torque.

Keith Tedford
Jan 28th, 11, 8:30 PM
Just a side note. Loctite also has a 747 sealant for stainless steel. Perhaps it has anti-gauling properties but that is just a guess.

d1_bradley
Jan 28th, 11, 9:03 PM
I use ARP thread sealer (teflon paste)

Fasglas
Jan 29th, 11, 4:02 AM
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.

I agree. I've used many different types of sealers over the years, but RTV is one of the last options on my list. RTV has killed a lot of motors by ending up in oil passages.

And to the OP, don't use so much sealer. Using too much sealer raises the chances of it ending up where you don't want it. A light coat on clean threads is all you need.

chrisstandring
Jan 29th, 11, 4:12 AM
Blue Hylomar has always worked well for me. Never a problem. The key point here is to use a non-hardening sealer. If it's good enough for Rolls Royce...

Malibu ss 64
Jan 29th, 11, 5:29 AM
I´ve used ARP´s teflon thread sealer on my last builds always use it when I use ARP headbolts has had good luck no leaks.

On builds with stock bolts I´ve had good luck with Loctites pipe sealer some yellow stuff.

Used silicon in the past but heard it can eat on threads?

Marcus