in a 92 4.3 tbi, the oil press. is around 60 when engine is running but cold, when it idles hot it drops to 15-20 especially when stopped in drive. but with rpms up and when im driving the press is back up to 60. plus with engine hot but off, the gauge on the digi dash will show almost no press. ive taken great lengths in the past to make sure i have no leaks. anyone have any ideas on what might be causing this. maybe a worn pump? i dont know but my blazer loses power during this.

 

The first thing I would do is remove the oil pressure sending unit and install an oil pressure guage to see if your pressure is dropping or it's just a faulty sending unit.
Did this problem start all of a sudden or gradually?

 

With many cars, the fault is more likely to be in the oil pressure sending unit than the actual pump. Check pressure as described above and I'll bet a new sending unit is all you need.

 

Thats the EXCACT same thing with my blazer, totally the same. All I do is check my oil level every other day, and if there is oil in there, I don't care what the gauge says. (Thats not a bad thing is it?)

 

i actually have changed the oil press. switch due to it leaking about a month ago. and the problem has been there since i bought the truck 5yrs ago but it has gradually gotten worse. im leaning towards worn rings or cylinders, plus i know due to oil deposits on a spark plug that i have a worn valve stem or guide . would that create loss of press as well.

 

Piston rings will not cause a lack of oil pressure, nor will bad valve seals or worn valve stems. The upper two rings retain cylinder compression while the lower ring scraps the oil off of the cylinder walls that slings up in there during operation. The valves are lubricated by the dripping/slinging of oil off of the rockers which is supplied through the push rods & lifters. Both the rings and valve seals could contribute to oil consumption if bad enough.

Things that can decrease your oil pressure are a worn pump and worn bearings (main, rod, and cam). Oil filters can decrease pressure to a certain extent, but shouldn't be that bad.

Oil deposits on the spark plug is most often a result of bad valve stem seals.

 

thanx for everyones help, it really eliminates any doubts on my part.
on that note i was always toying with rebuilding the top, but i wonder will it be more efficient and economical for me to just install factory rebuilt heads(valves,springs,rockers,keepers,pushrods,etc. ...).i heard it can get costly and very frustrating to try and do single valve jobs and then in the end others parts could eventually go. so i just need a push in the more righter direction. once again thanx for all the info. i not really thinkin that this will solve my press problem but i do know this should be done any way. i might have a slow very small leak of coolant internally, i believe against barsleaks so gettin to that gasket would be a double plus for me. all a matter of time and money. thanx