Oil pressure light & oil level light at startup

[Flyingeyepro]

Searched for a solution but couldn’t find an answer.

Recently swapped the M54B25 in my 2002 Roadster. Replacement motor was from a 2001, had 76k miles and seems in good shape. Everything works great, with the exception of these two warning lights at startup. The level light may be a damaged connector, or it may be related. Will swap at next oil change. The connector is a little beat up from transit.
Oil level on dipstick is good. Motor starts smoothly and idles without surging or dipping. If the motor is cold, the oil pressure light stays on for 8-10 seconds. The oil level light comes on after 2-3 seconds and off in 10-12 seconds after starting. The motor isn’t ticking or making any unexpected noises during that time.
If the motor is warm, the pressure light stays on for 1-3 seconds. The level light may or may not come on.
The oil is Mobil 0W-40. Filter is new, but small oil o-rings are not. CCV is new. No codes are shown. Oil filter housing gasket is new, everything looked good when swapped. Used motor sat in a dry warehouse, without oil for a few weeks before the install. Oil pan had no sludge, valve train was spotless. Where can I start to determine the cause?


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[z3forlife]

Swap the sender from your old block into the new one and see what happens

[328 Power 04]

Oil pressure test is ideal next step. Oil filter housing can be a cause of it all.

[Randy Forbes]

The level/temp sensor in the bottom of the pan is known to be prone to failure. If the one from the old engine is still good, use it, otherwise by a new one (consensus is to pay up for genuine BMW when it comes to sensors; the aftermarket crap is, well, crap).

[Flyingeyepro]

Circling back around to this. I have confirmed that the pressure is dropping at startup. And I believe the oil level is dropping too. I replaced the oil filter housing and gasket. I made sure the oil filter housing check valve was working. I suspected that it may be caused by the oil anti-drainback check valve under the head. Not wanting to pull the head, I tried Seafoam, without success. My next step is to remove the oil pan and inspect the oil pump. Any ideas before I do this would be greatly appreciated.

On a side note. I have since found out that the replacement motor I installed was not from a Z3. I suspect it was from a 325. I had to swap the oil pan cover to fit. Are the oil pickup tubes different? Did I miss that? Would it cause this issue? What’s the frequency Kenneth?

[Flyingeyepro]

To bring this back up to the top, is it possible that something in the Vanos system could cause these symptoms?

[Adker]

Did you swap the entire pan or just the bottom cover? Are you sure you have enough oil in it, could be the dip stick is wrong. I would look up the engine spec (6.5 l?) drain your oil and measure how much you are running.

[Tigershark48]

Good idea, but if he swapped the oil pan, the spec for the replacement engine could be incorrect. Checking the spec for whatever engine the replacement pan came from is another possibility. The dip stick from the old engine might give a more accurate reading as well.

[Adker]

I think they are the same capacity. I am guessing the dipstick is wacked. I have had this happen to me on another car with a swapped engine, was off by about one quart. Turned out the dipstick tube was not right for the dipstick.

Original engine ;
z3 2002 M54B25 6.5 l

Replacement engine:
325i 2001 M54B25 6.5 l

[Flyingeyepro]

I swapped the entire oil pan with a new gasket. I also replaced the 325 dipstick and tube with the ones off my engine. The 325 tube was a different shape.

During this last oil change, I was careful about measuring how much oil was required to reach the full level on the dipstick. Almost exactly 6.5 qts to reach the proper level. I went ahead and overfilled by 1/2 qt to see if it made a difference. It didn’t seem to.

I’m perplexed as to how the oil level can drop without the pressure going up. Anyone got a diagram of the oil circuit? Where does it go after the pump? And where could it loose cold start pressure or volume?


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[Muzz258]

Check out the below link. The different BMW engines have different ways to control the oil squirters so check them out on your old engine to see how they work.
https://www.bimmerforums.com/forum/s...e-at-Idle-Info

[Adker]

The oil pump pressure relief would bypass the oil but why would it stick at startup all the time. At least pull out the piston and spring and inspect the bore if you go back into the pan. A crack in the pickup could cause a slow prime but that shouldn't drop the oil level. Strange