Need advice -- oil galley plug, What to seal with? Options

[BillC]

I think I found the oil leak on the bottom of my engine. When they rebuilt it, they installed screw-in oil galley plugs. This one, on the front of the engine, appears to be the leak -- it was a little loose and there was oil all over the back of the motor mount bracket.


The plug is 22mm with 1.5mm thread, straight thread (no taper), and is fairly short. It looks like they might have used a very small amount of gasket shellac to seal it originally. They did stake the plug, and it didn't rotate, but it unscrewed very easily and turned-in just a little past the stake when I tried putting it back in.

What should I use to seal this plug? I'm guessing pipe dope isn't the right stuff, since the plug isn't tapered. More gasket shellac? Red loctite? Something else?

Thanks!

[Geezer914]

I used aluminum pipe plugs with ARP thread sealant, no leaks.

[BillC]

I used aluminum pipe plugs with ARP thread sealant, no leaks.

@Geezer914 What size aluminum plugs did you use, and where did you get them?

I've been googling, and found only one place that listed M22x1.5 aluminum plugs, but they were out of stock. Apparently used by some Fiats.

I'm thinking about trying to make an aluminum plug, but not sure how to drive it. Don't have the tools to cut an internal hex hole.

[Superhawk996]

I used aluminum pipe plugs with ARP thread sealant, no leaks.

@Geezer914 What size aluminum plugs did you use, and where did you get them?

I've been googling, and found only one place that listed M22x1.5 aluminum plugs, but they were out of stock. Apparently used by some Fiats.

I'm thinking about trying to make an aluminum plug, but not sure how to drive it. Don't have the tools to cut an internal hex hole.

Mill cut a slot or external hex with crush washer was what I’m considering. Both easy to turn on lathe.

The other thing I’ve done in past is to heat billet near plastic deformation (steel or aluminum - works with either) - hammer drive or press in hex (old allen wrench as form tool). Then turn the billet to what you need to duplicate original plug size and threadform.

[BillC]

I used aluminum pipe plugs with ARP thread sealant, no leaks.

@Geezer914 What size aluminum plugs did you use, and where did you get them?

I've been googling, and found only one place that listed M22x1.5 aluminum plugs, but they were out of stock. Apparently used by some Fiats.

I'm thinking about trying to make an aluminum plug, but not sure how to drive it. Don't have the tools to cut an internal hex hole.

Mill cut a slot or external hex with crush washer was what I’m considering. Both easy to turn on lathe.

The other thing I’ve done in past is to heat billet near plastic deformation (steel or aluminum - works with either) - hammer drive or press in hex (old allen wrench as form tool). Then turn the billet to what you need to duplicate original plug size and threadform.

I thought about the slot, it's pretty simple. External hex won't work because the stock engine mount bracket sits right on top of the threaded boss -- there's very little room between the boss and the bracket.

I'm going to try a different approach first. I ordered a couple of aluminum 3/4" NPT pipe plugs. They already have an internal hex, even if it is SAE and not metric. The plan is to turn down the outside of a plug and rethread it to M22x1.5. The plug shouldn't require a lot of torque, so I'll cut some of the hex end off to get it to the right thickness. Then, I'll use some Loctite 574 for sealant (amazon has small tubes of it).