when you start it the oil preasure stays up high tell it warms up then it will drop to zero preasure,the truck has set for 2 years and was drove 2 miles home with no preasure problems but when started back up the next day the oil preasure droped, we have got a new oil pump for it but want to know what would be the best way to go about getting it changed, have heard to pull the motor but also been told can remove the axel, can anyone explain how to remove the axel? or is it better to pull the motor.
thank you

 

What are you driving? Vehicle information will dictate the proper approach.

Have you verified that the pressure reading displayed on the dash is accurate with a mechanical gauge yet?

 

sorry not thinking right,
its a 1990 s-10 4x4 we did check the preasure from the port by the filter says its only running 0 psi but when you frist start it the preasure is up above 40 but warms up and drops to 0

 

You can either pull the motor or drop the front diff out. The front diff is probably easier, especially if it has the flanged CV attachment type front diff.

 

how do you drop the diff out? could you please explain it so we can do it
thank you so much

 

There really isn't much to it. Disconnect the drive shaft, remove the CV shafts, disconnect the front axle engagement cable, and then remove the bolts that fasten it to the frame.

 

Personally I don't think you have an oil pump problem. It sounds like maybe something in the pressure relief may be sticking. Try taking the oil filter adapter off and thoroughly cleaning it and where it mounts along with changing the oil. All you're out is a gasket, oil filter and some oil and it sure is a lot less work than changing a pump. Either the pump pumps or it doesn't. They don't go bad sitting.

 

I would try the oil pressure sending unit. Every V6 Z24 I've owned (4) had a problem with showing 0psi when warm. After replacing the sensor, it was fine.
Maybe it's genetic to GM? LOL

If the motor doesn't cut out when it hits 0 psi, I would really check the sensor. There should be another sensor for the PCM for oil pressure (every car I've put my hands on has one) that would let the PCM shut down the motor if there was no oil pressure to prevent damage.

 

It isn't the sensor since he already checked with a manual gauge, and these engines will run at 0 psi until they blow they wont shutdown. It sounds like something get sucked up to the pump screen after it has been running, which does mean pulling the differential or the engine to get the oil pan off.

 

THANK YOU SO MUCH FOR ALL YOUR HELP
they have been working on it all weekend, they got the diff off and the oil pan out and discovered that there was about 5 inches of oil that lookes like tar and the filter in the pan was cloged very bad. there finishing putting the diff in today. this truck has always ran very good i will be soooo glad to be back in my blazer.. thanks again