Hello everyone, I have a HP 500 that has two small cracks in cylinders in a gen 5 block. I just received my brand new gen 6 block. From what I’m seeing online I need to change out the 11psi bypass valve and install a 30 psi part # gm 25161284.. here’s where I’m confused, the 25161284 is very easy to push and override the spring tension, the one that came in the block is way harder to push. So does it already have the 30 psi valve in it and the one I got from GM is packaged wrong or doing the reading on here that part # isn’t correct for the 30 psi? The one in the block is much harder to push open, I’d say about double which would make me believe it’s the 30 psi…..
also any input on timing chain covers for the gen 6 and single roller chain?
thanks everyone

use a mercury aluminum gen 6 cover and I like Cloyes ? for the timing set

It was recommended to by Eddie Young to plug that bypass with a freeze plug. I don't remember the size, but they are readily available at the parts store. I have probably done a half dozen of them that way with no ill effects.

Mine was drilled and tapped then a screw in plug installed.

I just want to say that I have seen 2 engine ruined because of blocked bypasses in the last 30 years. I have never seen one hurt because it had a bypass.

If you do get talked into blocking it make sure you understand that you have to follow a good start up and warm up regime.

Curious as to what the failure was?

Oil filter came apart internally on a cold start and the filter material got into and blocked the main oil feed. Not enough warm up time. They were both small blocks and did not have the highest quality filters on them. They were both performance car engines. I did not build them.

Personally I figure if something has gone wrong to the point that metal is getting in the oil then it doesn't matter if you have a bypass or not.

Marine engines ?
I ask about marine, because most get used in warm weather.

True but the cold water cooling typically takes longer to get oil temperature up.

These were both high performance automotive engines and the failures happened in warm weather. A real high quality racing type filter might have not failed but I still prefer to leave the bypasses in place on anything I build. You really can never tell what the end user will do.

Prob with the bypass and marine remote filter is if you are bypassing alot you are not getting that bypassed oil thru the oil cooler…..thus why the higher valve relief or using a plug.