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

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

Post by Krooser »

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

Post by Belgian1979 »

Coming back to this. I decided to use Loctite 518 as suggested above. It doesn't seem to harden...is that normal?
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Schurkey »

modok wrote: Tue Jul 27, 2021 9:25 pm I agree. Part numbers 565, 567, 545 all seem the same to me... ...592 has a high temp rating but I have not found that to be needed. Probably does not hurt tho

I dug around the Permatex/Loctite catalogs a while ago. They're not real clear on what the differences are, so I may be off a bit.
565 is low-strength anaerobic. Fast cure time.
567 is low-strength anaerobic. Slower cure time.
592 is high-strength anaerobic. High temperature resistant. Couple of hours cure time.

I'd like someone to confirm the above, I'm not real confident. Point being, the "strength" of the anaerobic cure varies, as does the cure time, and temperature range of the various formulations. But it all looks and smells the same. Cure time could be important if you're sealing headbolts that need to be retorqued hours later after the engine is test-fired.
modok wrote: Tue Jul 27, 2021 9:25 pmI think it is often re-branded as genuine (insert corporate name here) brand, which is fine but then you pay 2-4x the price
I'm convinced that ARP sealant is one of the Permatex "PST" sealers listed above--perhaps 592.
Belgian1979 wrote: Sun Aug 15, 2021 10:11 am Coming back to this. I decided to use Loctite 518 as suggested above. It doesn't seem to harden...is that normal?
modok wrote: Mon Jul 26, 2021 2:13 am 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.
518 is an anaerobic gel. It's not going to harden any place you can see it (any place exposed to air.)

If the metal of the engine and the core plug is clean, it'll harden/cure in between them.

Overall, I'd think 518 is too thick to work properly--pounding the core plug in place will just wipe most/all of it off. You'd be better off with a thin threadlocker like Loctite 242 "Blue" as recommended by GM. Also anaerobic, what you see is still going to be liquid. What's trapped between core plug and block will harden.

I used 271 "Red", but I'll switch to 242 based on the info in this thread.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Belgian1979 »

Thanks Shurkey.

The 518 is a bit like blue silicone but slightly more runny. I would have used the blue silicon, but have had bad experiences with it getting destroyed when it gets in contact with oil. Maybe I just try to put some water in the block when the manifold is on. I assume that for threads it will work though.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Walter R. Malik »

Belgian1979 wrote: Mon Aug 16, 2021 3:51 pm Thanks Shurkey.

The 518 is a bit like blue silicone but slightly more runny. I would have used the blue silicon, but have had bad experiences with it getting destroyed when it gets in contact with oil. Maybe I just try to put some water in the block when the manifold is on. I assume that for threads it will work though.
Silicone is not anaerobic ...blue or any other color.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by Schurkey »

Belgian1979 wrote: Mon Aug 16, 2021 3:51 pmI would have used the blue silicon, but have had bad experiences with it getting destroyed when it gets in contact with oil. Maybe I just try to put some water in the block when the manifold is on. I assume that for threads it will work though.
1. RTV Silicone is routinely used for valve cover sealing; oil shouldn't affect it. Gasoline does, though. RTV Silicone is the LAST product I'd use to seal core plugs.
2. For fook's sake, do not use RTV Silicone to seal bolt- or pipe threads. Especially if you need to re-torque the bolts later, after the silicone has cured--and re-torquing shreds it. And it's hateful to clean off of bolts, and out of threaded holes when disassembled later.
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by modok »

I use 518 sometimes to join together large surfaces of machine tool parts that bolt together.

The ooze at the seam never cures, it remains goopy literally years. And since I don't care, i just leave it there.
However the stuff in the gap cures full hard in two days. It may cure half way in under an hour. This is important because....on larger size pieces it can take many tons to break loose again, if I even can do it. I might have to tap some holes in order to take some of these things apart.
Sometimes I do take it apart, I may find big patches a few thou thick. It scrapes off with the same difficulty as cheap paint, and it comes off in sheets like cellophane, plastic wrap. It is basically plexi-glass.

95% of the time any manufactured thing.... it will be cleaned or painted or wiped away so you won't see any residue.
you see what I'm saying about shelf life? I could scrape up and collect the residue and still use it years later.....if it wasn't full of dirt.

518 is NOT ideal for cup plugs....
unless if the hole is rusted and pitted, then it's ideal.
if you are not sure, "on the fence" if the hole is scratched and pitted enough to need this sealant.... put more scratches and pits in it, wire brush the plug, and then go for it.
Am I joking? kinda....but, it WOULD work perfectly. it might actually be stronger :shock:

And you will hear the same about epoxy. The rougher the surfaces the stronger the bond.
But for the anerobic sealant the SCALE of the ideal roughness is much smaller.
For epoxy the ideal might be something like what you get with fresh 80 grit abrasive, or even rougher, depending on what epoxy and material.
For these anerobic sealants... freshly ground or machined or wire brushed surfaces are close to ideal as-is....emphasis on the fresh. The surfaces being freshly machined or sanded is even more important than them being clean. It can handle a small percentage of oil or dirt contamination and still work fine.
Loctite did a test with the threadlocker on different types of bolts. Zinc plated bolts with no prep ended up half strength or less, no surprise there.
Black oxide bolts cured the strongest, ironically....no matter if they cleaned the oil off or not. The results technically showed a stronger bold on the NOT cleaned bolts, but, difficult to say why..... but in any case below the margin or error so I'm saying equal
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Re: what sealant to use on expansion plugs, cam tunnel plug etc

Post by autogear »

We currently use blue Hylomar. It makes life so much easier, opposed to RTV. We did use import grey RTV, with a special pair of pliers (which really did make application a breeze and maximize product use)
There was a guy on the boards here that is a rep for these products. I forget his handle but his name is Brian.
We also use teflon paste, which is "similar" to one of the compounds ARP brands.
The only loctite I use on a current gearbox is GREEN loctite; which is for bearing and bushing mounting. New Venture Gear had an associated Chrysler/GM number for it of course.

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

Post by stealth »

JB weld on core plugs... Can use high pressure canister for coolant - will not blow out and water down the rear tires.

Smear the backside with epoxy prior to install also- eliminates any rust issue.

Can be removed with heat when needed.
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