View Full Version : No oil pressure HELP!!!!


wicked-98
07-07-2009, 09:14 PM
I just finished my engine swap today on my 98 Z28.It fired up fine but there is no oil pressure at all.I tried it 3 times in 10 second intervals and still nothing how do I know if the sending unit is bad or my oil pump or wires or gauge?please help

racecar
07-09-2009, 01:15 AM
Tell us about your engine build. What do you have, did you assemble it, or is it a crate motor. Most important: Did you put the blue O ring on the oil pump pickup? The plastic barbell in the oil passage above the filter, the freeze plug in the front of the block.
Did you check and double check the height of the pickup to the bottom of the oil pan.
If all of that is good, put a mechanical gauge on it, take out the spark plugs, disconnect the coils and injectors and crank it over, you should have oil in 10 seconds.

wicked-98
07-10-2009, 12:12 AM
I checked all of the above.As for the engine its a top end rebuild by me and a 15k mile short block I bought from someone.I pulled the oil filter today and it was dry as a bone so I think I'm gonna have to double check the pump o-ring. Is there anyway to check the oil pump itself or to prime the engine like the old school 350's???

ChucksZ06
07-10-2009, 09:39 AM
take spark plugs out to get rid of compression and spin it over for a few seconds every 10 minutes or so. I never fire mine until I see pressure. You will get 40 psi just from cranking...IF you have all the plugs in and everything is correct. The pump has to move enough air to create the vacuum that pulls the oil up out of the pan. I have never done it but I bet if you put a few qts. extra in the engine the pump would prime much quicker...then drain the excess off.

98Z28CobraKiller
07-10-2009, 10:58 AM
Probably too late now but you can pour some oil down the hole for the oil pressure sensor to help it prime. One issue that I had once was that I put the o-ring on the wrong side of the rolled lip on the pickup tube. The oring should be between the rolled lip and the bracket that bolts to the pump.

racecar
07-11-2009, 01:40 AM
When I put my new short block together, I put the pan and filter on, and cranked it as fast as I could with a breaker bar, after 15 revolutions no pressure, I pulled the plug on the side of the block, there was oil. After 30 turns no pressure, I pulled the filter, there was oil, it took a total of 40 revolutions to get oil pressure. It takes time to fill those oil galleys by the lifters. They have to be full to make pressure. If you let it run for 10 seconds, more than once, and oil has not made it to the filter, there is a problem with the pump.
Sorry, no way to check the pump without turning the crank. If you have ARP main studs, the nuts are taller, that will space the pickup down, if you did not check, it could be on the bottom of the pan. Yea, that happened to me.

blk00ss
07-11-2009, 05:31 AM
Oil plug in the back of the block.

wicked-98
07-11-2009, 03:15 PM
take spark plugs out to get rid of compression and spin it over for a few seconds every 10 minutes or so. I never fire mine until I see pressure. You will get 40 psi just from cranking...IF you have all the plugs in and everything is correct. The pump has to move enough air to create the vacuum that pulls the oil up out of the pan. I have never done it but I bet if you put a few qts. extra in the engine the pump would prime much quicker...then drain the excess off.

I was thinking about this one I'll try in a few days and return with results.If it doesn't work I'm pulling the pump!