1991 Buick Reatta no start.

[ReeRee]

Hey it's been a while since the last update but I figured out the stalling issue. Timing chain stretch ended up being the culprit. Swapped out the timing set oil pan gasket and switched to an AC Delco cps. I now have a new issue. After highway driving the oil pressure reads very low idling and stop fluctuating on bd71 around and under 20ish sometimes dipping as low as 4. Leaking oil on the passenger subframe but haven't yet found the source. Lost about 1 qt of oil in 2 hours a few days ago

[rogold99]

I am guessing the oil pressure switch is bad, or the oil filter is loose, or the filter has a bad o-ring.

[2seater]

It appears the oil pressure reading has been an issue right from the beginning of this thread. First it was pinned high, then indicated somewhat low and now hot idle is pretty poor for a 3800. The only way to know for sure is to connect an actual gauge. The dash reading and the BCM reading is using the same sending unit. It sounds like the oil leak is a new issue?

[DAVES89]

9 hours ago, rogold99 said:

I am guessing the oil pressure switch is bad, or the oil filter is loose, or the filter has a bad o-ring.

What has happened to me in the past [on mostly Chrysler products, wonder why] is the old O ring stays on the car and then the new filter goes on and now you have a double gasket which really lets oil pass. I agree check the filter.

[Barney Eaton]

Either potential problem is an easy fix. 

I would change the oil pressure sending unit regardless.... they are usually less than $20 at your local auto parts store. 

Also put on a new oil filter and make certain the mating surface is clean.   There is an outside chance that an old oil filter gasket stuck 

to the adaptor housing and that would make it easier for oil to leak there..... having two gaskets on the oil filter. 

[ReeRee]

Will check tightness of filter. Should be good as it is a new filter. The gasket for the oil filter housing was replaced 1 week ago and the oil pressure sending unit is relatively new and was replaced shortly after id originally made this thread.

 

[EmTee]

Check the oil pan interface and snug any loose bolts.  Also, valve covers can leak a surprising amount of oil...

[padgett]

GM says when in doubt to use a mechanical oil pressure gauge, I always keep a spare because they fail so often. Was even a TSB on the subject.