A little advice from the experts

[mnichols]

Gents, I drive an M3 but was hoping that some of the Porsche experts might have good advice for me. I started tracking my M3 this year, after much preparation around safety. The engine has remained stock, with more power than I need for a newbie.

After a recent track event, I had run the car hard with my improving driving skills and decided to change oil, and do a general tech inspection. After finishing up the maintenance, I restarted the engine and no oil pressure. The dip stick read full, I refilled it with the 7 qts as the manual suggests. I stopped and restarted the engine several times but the pressure remained at 0.

I removed the oil filter canister lid, and the canister was dry. No oil circulating in the engine. Believing I had the M3 classic problem of the oil drive gear nut falling off, I dropped the pan on the car and found everything ok.

I next removed the oil pump and took it apart. Wow, the pump case and gears are scored as if they ran without oil. I don't know how bad the damage needs to be for the pump to quit pumping, but this is much worse than I expected.

I removed the front cyclinder rod cap to see if the rod bearings were damaged, but I don't see any issues with them. The rod bearings look good, worn after 120K miles, but worn evenly with no scoring. The crank journal looks ok as well, however I can see a VERY light scoring on the crank. Don't know if this is normal for a engine of this age or not. I plan to have a local BMW doctor stop by the house and look at the crank to see if there was any damage.

I wouldn't expect an oil pump to fail this way merely due to age. So I'm worried that I starved the pump of oil during my track runs. I have a stock oil pan, with no baffles or improvements. I'm certainly not going to re-install the pan without one of the baffle kits. If you look at the pictures attached, the gear bearings and housing are severly scored. Does this look like pump fatigue, or age? With the rest of the engine looking ok, it seems odd that only the pump was starved of oil to the point of failure.

I normally glance at the dash while coming out of corners, or during hard braking, but have never seem the low oil pressure light come on. I don't have an oil pressure gauge on the car, so I don't know if the pressure was getting consistently lower. That is going to be corrected soon.

My next move is to use a plastigage to check rod bearing tolerances, just to assure myself that no damage was done, and to check the health of my engine. I'm also going to install the VAC baffle kit to help keep the oil near the pickup, but something is bothering me about oil starvation being the cause of this pump failure.

I don't want to take up bandwidth in your Porsche forum, so if you have any ideas my email addess is mnichols@cfl.rr.com

[mnichols]

[YTNUKLR]

I don't know for sure but I think this is the reason that most Porsche 911's (all the air-cooled ones, and newer GT2/GT3/Turbo) are dry-sump.

http://en.wikipedia.org/wiki/Dry_sump

"[D]ry sump designs are not susceptible to the oil starvation problems wet sump systems suffer from if the oil sloshes in the oil pan, temporarily uncovering the oil pump pickup tube...Many racing cars, supercars, and aerobatic aircraft also utilize dry-sump equipped engines because they prevent oil-starvation at high g loads."

[nocarrier]

Is this an e-46 with the s54?

I believe there was a campaign for this where the oil pump and con rod bearings are exchanged. As well as an update for the dme.

I will check for you.

[911quest]

Did you let it sit for any extended period of time before refilling??If so the pump could have lost its prime...

[mnichols]

Thanks for the responses. Its an E36, so I'm not aware of any service bulletins. That's a good idea though and I will also check.

The obvious low pressure problem began immediately after an oil change, I doubt the engine sat more than 15 minutes without oil. But I doubt the problem started during the oil change, I suspect it started long before.

I've never heard of an oil pump losing its prime, but that's why I'm asking. Is it possible that all of the damage to the pump happened in the 30 seconds it ran (3 -10 second low rpm runs) after the oil change?

[einreb]

Originally Posted by mnichols

Thanks for the responses. Its an E36, so I'm not aware of any service bulletins. That's a good idea though and I will also check.

The obvious low pressure problem began immediately after an oil change, I doubt the engine sat more than 15 minutes without oil. But I doubt the problem started during the oil change, I suspect it started long before.

I've never heard of an oil pump losing its prime, but that's why I'm asking. Is it possible that all of the damage to the pump happened in the 30 seconds it ran (3 -10 second low rpm runs) after the oil change?

Take this over to bimmerforums too for more input. This thread has some info on a similar situation (non-oil pump nut failure low oil pressure)

http://forums.bimmerforums.com/forum/showthread.php?t=562988

Was it just showing the light at idle? Slightly worn bearings... older 'thicker' oil holding pressure better than new lighter weight oil? (Grasping at straws... sorry!)