We are doing a complete rebuild of 2.0/4 motor, pistons were stuck in the cylinders. I have stripped it down to the bare case and curious as to how many "engine rebuilders" open up all the oil passage ways and do a good scrub of the galleys. As far as I can tell there was no catastrophic failure, bearing failure, broken rod, etc.

As always, thank you

I always do the main 5 with 3/8" NPT plugs, not so much for the nasty, but because these are the ones that can fail.

Pull em’.

There is no telling what is piled up in there just waiting for some old piece of swarf to come loose into your freshly built motor.

Same reason not to reuse an old oil cooler! No telling what’s in there.

Cleaning the galleys is cheap insurance unless you know the history of the motor which is not your situation.

Stainless steel hex plugs with teflon tape?

No, I use steel plugs with the micro-encapsulated sealant or red loctite.
You can also use liquid teflon pipe dope, but never the tape.

Thanks Mark, why no 316 stainless?

I guess you could but why? Stainless isn't the best in aluminum. I won't use stainless studs in the heads.
The only thing I do in stainless is cheese head screws, valves and exhaust systems.

"When aluminum and stainless steel are used in an assembly together, the electrons from the aluminum will begin to transfer into the stainless steel. This results in the aluminum weakening. This weakened aluminum causes it to deteriorate at a much faster rate."

https://www.albanycountyfasteners.com/blog/...l-and-aluminum/

Thanks guys, I have used aluminum and stainless for years and never knew of galvanic between the two.

Steel it is

Gun cleaning brushes for the oil galleys?

Yes, that's the popular option.

--DD

There is always galvanic action between two dissimilar metals. The degree of action (voltage) depends on the actual metals.

18-8 to Al/Mg alloys is pretty bad...much worse than mild steel (something like 8x higher galvanic potential difference IIRC).

Possible aluminum plugs are the way to go? If not, why? No expansion/contraction issues, no galvanic activity, .... I am not sure who has them, but I'm sure they are available

Since it is not s shear situation, that would be the best. No reaction between like materials. Heating and cooling should be the same