Lost oil pressure, can't figure out why - need help ASAP!

[Sterling Doc]

I have a new motor that I've have about 1/2 hour on - started, made good oil pressure through that time, right to the point I shut it off. Today, took it to a preseason T&T. Started this morning for the first time since running it last it - no ticks, seemed good, but low oil pressure light stayed on - shut it down after 20 sec or so (all less than 2K RPM). Cracked oil pressure line - no oil came out, and lifters started to tick when we briefly restarted it (after checking the OPRV), so no oil pressure is real. Oil is right at full mark, and looks as new.

 

Started to tear the motor down -

 

Oil pick up tube is OK

Oil pump looks OK.

No metal/debries in the oil

Plug at oil pump is intact (have seen these fall out dumping pressurized oil back into sump)

Pressurizing oil system with air reveals no hissing, obvious leaks

 

Help! 6 days 'till the season starts.

[roadracerwhite]

Andy and I had the same problem with his car, one day backing it off of the trailer it had no oil pressure. we ended up replacing the oil pump even though nothing looked wrong with the old one. It fixed the problem but I am not sure if it wasn't something else.

 

If there was an air passage in the inlet line, the pump would not be able to pick anything up from the pan. (like a broken dringking straw)

 

Bryan

[Tim Comeau]

Eric,

What do you mean oil pressure "line?" Cracked oil pressure line - no oil came out,

Why would the lifters start ticking if they were just filled up a little earlier?

I would look to the OPRV again? Something could be sticking?

 

Once the oil pump has filled with oil it shouldn't need priming again. What exact kind of oil filter are you using?

[MadConan]

Eric, I know what of the MN guys had the same problem. The oil pickup tube was cracked. Like Bryan said, if there's a crack above the oil level, it'll suck up air instead of oil.

[MadConan]

i see now you say the pickup tube is ok. did you check to see if the bolts are loose where it attaches to the block?

[Sterling Doc]

Well, we put it all together again, and had to work hard to get the pump to prime - lots of air pressure through the dipstick, and cranking (with the plugs out), but once it primped, now have 80 PSI cold at idle, 95 at 2K RPM (cold), and can let the car sit for a while, and it instantly makes pressure restarting it. Not sure what happened, but it did it while the car was sitting (off). As it had oil pressure when I shut it off and none when it was turned back on. I was using a Mahle filter, but still wonder if it didn't have a bad anti-drainback valve, and the pump lost it's prime.

[Chuck T.]

I had an engine that needed to be primed if it sat for more than a week. after quite a few months it started working normal...

[944-Spec#94]

Well, we put it all together again, and had to work hard to get the pump to prime - lots of air pressure through the dipstick, and cranking (with the plugs out), but once it primped, now have 80 PSI cold at idle, 95 at 2K RPM (cold), and can let the car sit for a while, and it instantly makes pressure restarting it. Not sure what happened, but it did it while the car was sitting (off). As it had oil pressure when I shut it off and none when it was turned back on. I was using a Mahle filter, but still wonder if it didn't have a bad anti-drainback valve, and the pump lost it's prime.

 

 

If it happens again replace the oil filter. The drain back feature could be bad.

[Sterling Doc]

Joe - did put a new oil filter on last night.

 

Started it this morning, got 5-8 seconds of no oil pressure & lifter rattle, then 80PSI pressure. Getting a new OPRV sent overnight. Seems fine when it's running, but definitely having issues with drain-down when it's sitting, even overnight. I'll bring my air compressor to the track!

[944-Spec#94]

Joe - did put a new oil filter on last night.

 

Started it this morning, got 5-8 seconds of no oil pressure & lifter rattle, then 80PSI pressure. Getting a new OPRV sent overnight. Seems fine when it's running, but definitely having issues with drain-down when it's sitting, even overnight. I'll bring my air compressor to the track!

 

 

Two things.

 

1) Is the housing for the OPRV aligned right?

 

2) OPRV could be bad.

 

I did once have bad oil filter cause slow oil pressure at start-up, but once changed the problem went away.

[Tim Comeau]

So.....oil filter or OPRV?

BTW, we use the OC 75 filter from the 944 turbo's. It provides a little more oil and a little more filtration, but no performance advantage.

[944-Spec#94]

So.....oil filter or OPRV?

BTW, we use the OC 75 filter from the 944 turbo's. It provides a little more oil and a little more filtration, but no performance advantage.

That is a 928 filter. The Turbo uses the same filter as the 944 OC-42

[Tim Comeau]

Joe,

Here's a blurb from the Clark's Garage page.

--------------------------------------------------------------

Mahle OC 142 * Oil Filter OR Porsche OEM Filter (944 107 201 90)

Oil

Approximately 5.5 liters (5.8 US quarts) filled to the upper dipstick mark

Oil Drain Plug Seal Ring (26 x 32 mm - 900 123 049 30)

* You may also use the Mahle OC 75 Oil Filter which is a taller version of the OC 142. This filter was used on some 911 Turbo models.

I thought my guy at SSF told me the OC-75 was a 944 turbo filter, not a 911 turbo filter.

The OC- 46 is the 928 oil filter according to PARAGON.

[Sterling Doc]

Looks like it was the OPRV.

[loftygoals]

So did you run at RA?

 

-bj

[Sterling Doc]

Yup, just had to prime the oil pump with air pressure on the first morning.