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ok so i finally get a new motor in my blazer. 4.3 v6. nothin special just a stock motor. its had a few new things put in it.

new bearings
all new gaskets
new oil pump
new screen
and a few other things.

well heres my problem.

when i crank it everything is fine. but as the motor warms up, the oil pressure gets lower. it still goes up when i hit the gas and drops when it idles. but normally its about 40 psi at cruising speed. and would drop to around 20 at idle. now it cruises at 20 and drops to 0 when it idles.

the motor seems to be running fine as far as i can tell. no knocking, leaks, etc. but this scares me cuz it was a pain in the ass gettin this thing running again cuz i moved away from my hometown and rarely got to work on it. and i need it to drive to work.

i have talked to a couple people and tried lookin up online. cant find too much. but do have a few ideas.


bad sending unit
bad gauges
bad bearings.

a few things to add. i have the digital gauges. which have given me problems before. and could be the issue now because my gas gauge seems to be off and the trip meter keeps reseting. but all other gauges seem to be working fine.

and i cant just go buy a new gauge or sending unit and that not be the problem cuz i been out of a job for 2 months and just started workin again today. and im not sure if i can borrow a gauge from someone. but if im able to can someone tell me exactly how to check it?

also i dont see how the bearings couldve worn out that fast because ive only put about 170 miles on this motor. and its been doin it since i first drove it. it never did it just sitting because i never left it running long enough to get it all the way hot.

so does anyone have any opinions. i need to have this fixed by this weekend because i have to go see my dad for fathers day.

any help or ways to figure out the problem would be appreciaed guys. (and girls)

First thing to do is use a mechanical guage. you can possably barrow one from a mechanic shop. They run around 20 bucks new. If you still have oil problems then the most common problems is bad cam berrings. or if it is a Vortek bad counter shaft berrings. Did you build the engine or a machine shop? If they are new berrings and the cam was polished they coulc have been the wrong size. Very rarely the pump pick up tube or the bolts come loose. If it is low oil pressure DON'T drive it. You will destroy it.

I would try the oil pressure sending unit first. Its a cheap sensor that should be easy to replace. Had one go out on my F150, oil pressure would dip under acceleration and hard cornering. Not quite what you got but I'm sure they have more symptoms than what I had. The part cost 8 bucks for my ford so I'm sure it isnt much for your blazer, Try it, you wont be out much if that isnt the problem