M50 swap runs, but with no oil pressure

[88E30M50]

Yesterday was the big day when I turned the key on my M50 swap and she fired right up. After a couple of seconds with the oil pressure light still on, I shut her down. I pulled the fp relay and cranked for a little while to see if the oil pressure would come up, but got nothing. pulled the oil filter cap and there is about an inch of oil in the bottom of the housing, so I think there is some flow, but not nearly enough to run her.

This swap is using and M50 from a 93 325i, and had the oil pan and pickup swapped from a 91 M50 from a 525i. I did not swap oil pumps, since there was over 300K on the M50 out of the E34. The M50 I used from the E36 had about 121K and is in pretty good condition. When I did the swap, I just pulled the E36 pan, windage tray and pickup assembly and then installed the pickup tube from the E34 with the oil pan from the E34.

Did I miss something when swapping the oil pan and tube? If so, is it possible to pull the pan from an M50 in an E30 while in the car? Where is the easiest place to tap into for a mechanical guage?

Oh, and yes I did check the oil and it's right where it should be with almost 7 quarts in the car.

Thanks,
Tim

[hoveringuy]

I don't think you missed anything. I'm wondering if it's an electrical issue or really an oil pressure issue. Since the light is coming on I'm guessing it's wired correctly. One easy thing you could try is to disconnect the oil line to the VANOS unit and crank it over. Does oil squirt out? Better yet, read the oil pressure directly.

It could also be as simple as the lines were still purging the air out.

[88E30M50]

How much cranking would normally be needed to purge the air out of the system? I hope that is all it is, but with the amount of cranking done so far, am guessing it is not. I've got a charger on the battery right now and will give it another shot in about an hour.

Where is the best point to tap for pressure? The pressure sender on the back of the housing looks like it would work. While waiting on the battery to charge, I should probably run out and pick up a gauge to toss on. If it's getting pressure, I can move on with the project and start the finishing work.

[g22]

I'm having this same issue. Did you get this resolved?

[g22]

Used the Bentley testing proceedures and determined that the actual sensor was not functioning properly. I replaced the sensor and it worked. It took about 4 or 5 minutes of total cranking to get the pressure light to go out.