I just installed a new cam, valve springs, ported ls6 oil pump and ls2 timing chain. Started the car today oil pressure was ~5psi revved the engine a little and pressure went to ~40 but then dropped to 0. Would go up when engine revved but read 0 otherwise. Does this sound like a problem with the o-ring? Could it be the oil pressure sending unit? I tried a search and couldn't find anything. I am using 10w30 penzoil platinum oil. Thanks in advance.

 

O ring more than likely. Change it. If it looks fine when you pull it I would probably change the pump. Or even pull the cam and check the cam bearings. It's very unusual for the sending units to go bad. In my experience anyway. Someone will be all shortly to tell me I'm dumb and it happens all the time.

 

I reused the old o ring. That's probably the problem. Was hoping it was something a little more simple.

 

Wow

 

I thought I read somewhere it was ok to reuse. I guess that was a big mistake .

 

Yep, time to start taking it apart again.

I'm doing something similar, except I have lower pressure than I would like at hot idle. I'm also replacing my cam retainer / cam gasket plate while I have it all apart. I'm not taking any chances.

I used a new o-ring, but I suspect it's pinched or twisted somehow.