Oil pressure emergency

netmazk · #1 (**permalink**) 10-15-06, 05:12 PM

Yesterday I swapped my alternator out (1995 Aurora) for a new one and everything went perfect. I hadn't changed the oil in about 4k miles so I figured I would also tackle that today. Well, I drained all the oil and replaced the filter with an AC Delco PF61 (same as I had before) and refilled the car up with 7.5 quarts of Mobil 1 Clean 5000 oil.

I started up the car to back it down the ramps and immediately the DIC shows 0psi oil pressure and the "low oil pressure" message comes out and the bells go off. I shut her off and checked the oil pressure sensor, the connections were fine so I pulled the new oil filter off. However, NO oil came out when I took the filter off!!

I tried the old filter again thinking it might be plugged and I have the same problem. It's been a while now and I've started the car a few times with the same result. Now I can hear the valves tapping and you can tell the engine is being starved of oil!

Anyways, I'm guessing that my oil pump took a dump on me, but why? What are my options here? I'm tempted to drop the oil pan, but none of the stores around here have the pan gasket set in stock, not to mention i've never dropped the pan on this car before. I've read about overfilling the pan with an additional 8qts of oil on the N*. Does this also apply to the 4.0L Aurora version? Is there any way giving this a shot can possibly cause more damage? Thanks in advance for any advice you guys can provide. It's somewhat urgent as I'm home from school for the weekend and I need to get back to school tomorrow or tuesday at the latest!

zonie77 · #2 (**permalink**) 10-15-06, 05:32 PM

I think the oil pump can lose it's prime. The fix is to overfill, I think an extra 6 or 8 qts, and start it, then drain the excess.

I havn't had to do this but it's been written about a few times.

**Ranger** · #3 (**permalink**) 10-15-06, 05:37 PM

The oil pump is not submerged. It has a check valve to prevent it from loosing its prime. If the check valve gets stuck open it can loose its prime. If I recall the Guru's advice correctly, overfill the crankcase by 8 qt.s. That will submerge the pump. Now you can start it and reprime it. I believe he also said to rev to 4K a few times, then drain back to proper level.

Edit:
Zonie types faster than I.

netmazk · #4 (**permalink**) 10-15-06, 07:52 PM

Thanks guys the problem has been resolved!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ;D

I ended up following the overfill guide found in a GM TSB. I added 10 additional quarts of oil over the 7.5 I already had in there. Then it instructs you to start the car and rev her to 3500 and back to idle. Well, I added the 10 quarts, started her up and the whole car began to shake. Needles to say, I was scared shitless, but I figured I had nothing to lose (since I was following a TSB from GM) and stepped on the gas pedal. Revs climbed very slowly to 3k and then "pop", it dislodged whatever was stuck in the oil pump relief valve and my oil pressure was restored! I then drained all the additional oil and now my car is running GREAT!

**Ranger** · #5 (**permalink**) 10-15-06, 08:14 PM

Great!

That is the first time I have ever heard any feedback from someone who has tried it. Thanks for letting us know how it worked out.

ewill3rd · #6 (**permalink**) 10-15-06, 08:17 PM

Wow, that's a real scare-a-thon!
Good job fixing that one on your own.
I had fearful visions while I read your original post!

krimson_cardnal · #7 (**permalink**) 10-16-06, 11:01 AM

Quote:

Originally Posted by netmazk

Thanks guys the problem has been resolved!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ;D

I ended up following the overfill guide found in a GM TSB. I added 10 additional quarts of oil over the 7.5 I already had in there. Then it instructs you to start the car and rev her to 3500 and back to idle. Well, I added the 10 quarts, started her up and the whole car began to shake. Needles to say, I was scared shitless, but I figured I had nothing to lose (since I was following a TSB from GM) and stepped on the gas pedal. Revs climbed very slowly to 3k and then "pop", it dislodged whatever was stuck in the oil pump relief valve and my oil pressure was restored! I then drained all the additional oil and now my car is running GREAT!

That is unbelievable!!! Who would ever figure that??? WellDone

chevelle · #8 (**permalink**) 10-16-06, 11:27 PM

This is an uncommon but possible situation with the oil pump pressure regulator valve sticking open on shutdown on a tiny bit of debris in the oil. If the relief valve valve sticks open the pump cannot prime on startup if it drains down sufficiently. Deliberately overfilling the sump so that the (overfull) oil level reaches the pump and submerges it forces the pump to prime and revving it slightly will clear the debris from the check valve. Very uncommon but not unheard of.

No real danger of harming anything in the engine but be sure to drain the oil level back to standard before driving or operating the engine any further.

dp102288 · #9 (**permalink**) 10-17-06, 10:13 AM

oh man I would be so scared to try that!! Glad to hear it worked, now I know.

jones105n · #10 (**permalink**) 01-05-07, 10:17 AM

hi guys. just had the same shit happen to my 95 concours. changed the oil on thursday. wife drove it to the grocery on sunday and the "DREADED MESSAGE" appeared. called AAA to bring it home. found your advice on here and followed up using GM's TSB. overfill 10-12 qts. and reve to 3500 and back to idle to dislodge debris. i was scared to death but felt empowered by the TSB being printed and in my lawyer's hot little hand. it worked perfectly but i was shaking the entire time. completely drained and refilled with rotella 15w40 and new filter. good as new. thanks to all!!!!!!!!!! the gm TSB is as follows Bulletin #47-61-32B good info.