what sealant to use on expansion plugs, cam tunnel plug etc

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Belgian1979
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what sealant to use on expansion plugs, cam tunnel plug etc

Post by Belgian1979 »

Ok, stupid question, but the previous blocks had all of these installed, so bear with me.
What type of sealant do you use for the various expansion plugs, threaded plugs and cam tunnel plug?

I assume that for the plugs in contact with the coolant, I can just use blue silicone, but what with the cam tunnel and threaded plugs that come in contact with the oil. I know the blue silicone doesn't hold up with oil..

Thanks.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by AA Performance »

Always used Permatex non hardening aviation sealer.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Belgian1979 »

also for the ones in contact with oil?
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by mag2555 »

Gray form-a-gasket is what I have used for 45 years.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by BillK »

I imagine if you ask 100 engine builders you will get 100 different answers :) I have always used Permatex Indian Head gasket shellac on the pressed in "freeze" plugs and the cam plug. Real easy to apply with the built in applicator. Screw in plugs get Permatex white teflon pipe thread sealer. If they are oil galley plugs in the front of the block or anywhere that a leak would not matter they just get oil. Lately the Pioneer screw in plugs have been coming with a red sealer already on them so nothing additional on those.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Walter R. Malik »

Ford Motor Company and I use an anaerobic sealant ... any brand would probably do.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by 77cruiser »

Usually #2 permatex, one I did I used JB weld. Can't remember why, maybe the holes in the block looked rough.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Schurkey »

I used to use epoxy on press-fit plugs.

Now I use Loctite 271 threadlocker; or the equivalent.

Silicone RTV is practically a lubricant. No way I trust it to hold a press-fit plug under pressure.

Threaded plugs, head bolts, etc. get sealed with Loctite/Permatex "PST"; there's several versions and they all work wonderfully. Loctite 592 is the easiest to source around here.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by modok »

Loctite 565 for threaded plugs that may need to be removed someday. It does a fantastic job of sealing and reducing friction, cures hard, and is easy to remove later. Long shelf life. it is has been often re-branded and sold under different names, or there are other numbers that are kind of the same, I just use 565 because it's the one I remember.

Full strength loctite sleeve retainer for permanent plugs ( I use permatex brand because it's cheaper and has longer shelf life)

loctite 518 can be a "problem solver" for loose fits, scratches, or pitted surfaces. If the actual gaps are in the range of .005-.015" then this will work better than epoxy. 518 has become the most popular of this type of sealant, it is designed to be slightly flexible and cure well on aluminum, but for some apps.... others sealants can be better. 515 has better glycol resistance, 510 has superior hot strength.

As with all loctite type anerobic sealants..... nonreactive surfaces should be scuffed or primed for faster cure and best strength. i rarely use primer, rather sand, scuff, or wire brush the thing right before installing.

I'll also use permatex 2/3/300/aviation for some things, it's easy to work with.......but I only use it where I'm not worried about any problems.......,plays nice with glycol, plays nice with neoprene too, but I don't use it for threaded plugs, it really jams threads after a few years.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by rebelrouser »

As a n automotive instructor, we had several guest speakers for the students, one of them was a rep from the permatex company, he did a super presentation explaining the right way to use all their products, gave the students free sample for their toolboxes. And for freeze plugs he promoted using the hardening permatex no. 1

"Fast-drying, hard-setting sealant designed for sealing rigid materials and flanges, or patching holes and joints where permanent assembly is desired. Temperature range -65°F to 400°F (-54°C to 204°C); resists common shop fluids and fuels."

I have also used Anaerobic sealer as well. But as mentioned, lots of sealers will seal a freeze plug. I have gotten a few freeze plug sets that did not fit as tight as I liked, most were made in china, so I would return them, if they drove in a little too easy.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Baprace »

AA Performance wrote: Sun Jul 25, 2021 5:20 am Always used Permatex non hardening aviation sealer.
Same here , have never had any problems . 50 years plus.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by jsgarage »

On my street builds, I don't use any freeze plug sealant but I do use Dorman all-brass deep side plugs on heads and blocks, and I carefully install them with the correct drivers. I've seen (and bought) too many engines with rusted out steel freeze plugs, and distorted brass plugs from just hammering them in. Never had a Dorman brass plug fit loosely.

On cam tunnel plugs, I avoid the problem altogether by making up an aluminum plug sealed with an o-ring, retained with two button-head or flathead allens. Since the pushrod Ford V-8s I usually work on all have cam retention flanges built into their designs, cam walk that might bump out a cam tunnel plug is mostly non-existent. In my limited # of builds, it works for me.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by rebelyell »

BillK wrote: Sun Jul 25, 2021 10:08 am I imagine if you ask 100 engine builders you will get 100 different answers :) I have always used Permatex Indian Head gasket shellac on the pressed in "freeze" plugs and the cam plug. Real easy to apply with the built in applicator. Screw in plugs get Permatex white teflon pipe thread sealer. If they are oil galley plugs in the front of the block or anywhere that a leak would not matter they just get oil. Lately the Pioneer screw in plugs have been coming with a red sealer already on them so nothing additional on those.
#101
Looking through a 20 yo service manual published by GM Powertrain for GM 5.7L rpo L31 & 5.0L rpo L30 (both are Vortec w/ iron head & block)

see sections 6-104 thru 6-107
http://www.kohlerpower.com/onlinecatalog/pdf/tp6104.pdf

for the Threaded plugs, GM specifies sealer GM P/N 12346004 (teflon pipe thread paste)

for the Expansion plugs, GM specifies sealer GM P/N 12345382 (blue threadlocker)

https://permatex.com.ua/wp-content/uplo ... ex-OEM.pdf
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Schurkey »

rebelyell wrote: Tue Jul 27, 2021 10:10 am for the Threaded plugs, GM specifies sealer GM P/N 12346004 (teflon pipe thread paste)

for the Expansion plugs, GM specifies sealer GM P/N 12345382 (blue threadlocker)

https://permatex.com.ua/wp-content/uplo ... ex-OEM.pdf
The problem with the Permatex .pdf is that it doesn't include the Permatex product numbers. A considerable mistake on their part, I think.

I'm reasonably certain that the thread sealant is PST 592. Loctite/Permatex 565, 567, and the semi-solid "stick" of PST are all similar, all terrific. But 592 is what I use.

The "blue threadlocker" is almost certainly Permatex 242.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by modok »

I agree. Part numbers 565, 567, 545 all seem the same to me. I think it is often re-branded as genuine (insert corporate name here) brand, which is fine but then you pay 2-4x the price :shock:
592 has a high temp rating but I have not found that to be needed. Probably does not hurt tho

And in any case not for cup plugs :P At least, not IMO
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