Oil Pressure light at idle.

#1

My oil pressure light now come on when the engine is at operating temperature and when the engine speed is at idle. Once the rpms increase the light goes off and stays off. I have 124k on the engine. Problem started at Summit Point a few weeks ago. I changed the oil and filter and replaced the oil press. sending unit. Same problem. Anybody have/had this problem? I’ve checked some BMW forums and really didn’t find any solutions, except that this can occur. The BMW owners man. indicates that this might happen briefly

#2

The first thing I’d want to know is what the oil pressure is on a hot engine. You should see over 7psi at idle if the appropriate oil is used and the filter is good. And better than 10psi/1000rpm throughout the rev range.

The choice in filter matters. The OE filter has less restriction than the generics, in my experience, and I’ve never seen an OE filter suffer from internal collapse. But I have seen that happen with generics.

And the choice of oil matters. If you are going to take the car to the track a higher viscosity dyno oil (e.g. Castrol GTX 20w50) will help with pressure on an older engine. Just give the engine time to warm up well before driving it hard.

#3

318 sensors will get flakey then spew oil through at an alarming rate. I don’t know if the 325 part number is the same, or if they work they same way but it’d be an issue on track for sure. They are 10 bucks or less retail I think. Get a new one or a spare one and see if that fixes it.

#4

Mine does the same thing. Bill Revis, a reliable BMW mechanic, told me not to worry as long as the pressure is adequate under throttle.

#5

Mine did the same thing when I forgot to put 20/50 in one time…but once I changed the oil for 20/50, it went away.

#6

Here’s an update. I put a testing gauge on the engine and my at idle oil psi was 4-6 at operating temp. Cold opert temp psi started at 20 as the oil thins out from the heat pressure drops. Also noticed a silvery shine to my engine oil. With a flashlight you can see the metal specs. Dropped the pan on Sunday, inspected one main bearing and one rod bearing. Both bearings had evidence of a oil starved engine. You can tell by looking at the color of the bearing. Blue or black indicates oil starved. So it looks like at this point I’m going to pull the other caps off and inspect the crank journals for damage. I hope I caught this in time, before damage to the crank journals. My options are assuming the crank is good, 1. in car bottom end rebuild, remove head, timing belt all that fun stuff. 2. If the crank is damaged then it looks like the engine is coming out. My tranny throw out bearing is also beginning to fail so I was wondering how difficult is it to remove the transmission with the head off? Anybody have any other idea’s/opinions?

#7

My bad motor did that. Light went away once you got on the throttle. Smoked a bit. Rings were shot, cylinder walls were very glazed. I removed the head, found that out, then replaced the shortblock with a spare.

The engine removal was easier without the head, you can get to the bellhousing bolts much easier. I’d yank the motor, but we had my brothers tranny out with the motor in it. Still a PITA tho. Other than that, just disconnect the slave cylinder, motor mounts, bell housing bolts, radiator, electronics, and yank 'er out. Or, drop the exhaust, driveshaft, and yank the tranny. The motor was probably easier IMO.

BTW, get a good set of aftermarket motor mounts while at it. Replace clutch, unless it’s new. Do the throw-out bearing as well.

#8

Sounds like you should just pull the engine/tranny as a unit and do the work that way. You’ll save yourself time and hassle in the long run.

#9

+1

Its not very hard to pull the engine/tranny at once and makes it MUCH easier to work on the motor.

#10

For those of you with access to a lift…If you are pulling the engine/trans unit, consider just dropping the subframe with the whole assembly onto a couple pallets. Works very well, and is fast. Reassembly isn’t bad either, once you get the subframe lined up enough to get the bolts in.

Just don’t forget to disconnect the steering column from the rack.

#11

Thanks for the advice guys. My plan is to pull out the engine and tranny as a unit.

#12

David Mautone wrote:

that’s what I did, and worked well, even though Bentley says take off the tranny 1st

#13

When I pulled my engine and tranny together I just about had to force it out the hole. I had the hood off and the car on jack stands but to get it at the angle needed it still had to be forced. As a note, I did not have a preader but used a combination of straps and rotated it as needed. Does the leveler make this easier?

Michael

#14

Is there a write up on removing the engine and transmission together? I don’t have a lift but I do have a engine host and I have to change both the engine and transmission so I figured it would be easier to do it together.

#15

A load leveler is a must for removing the motor/tranny at once. This is how I did it this winter and had the motor out/in in less than an hour each, by myself.

#16

155MPH wrote:

a load leveler?

#17

#18

Great thanks for the picture a buddy has one I just never knew what it was called. So what is the best bet to remove it from the top from out the engine bay?

#19

Well I pulled the engine and trans out at the same time last month. You need the load leveler, a helper and a little patience. Once I had the engine/trans prepped for removal it took 30 minutes to pull it out of the car.