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peterpete190, Auto Technician
Category: BMW
Satisfied Customers: 28772
Experience:  Over 17 years diagnosing and repairing vehicles.
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I have a 1990 BMW 525i 2.5 sohc engine oil pressure is

Customer Question

I have a 1990 BMW 525i 2.5 sohc engine oil pressure is acting funny, had to have head reworked ever since putting it back on, oil pressure is low, when RPM goes up oil pressure goes down, RPM comes back down oil pressure goes up oil light goes off. Some
times oil pressure will stay good above 4k rpm some times cannot get above 1500 rpm before oil light comes on.Took oil pan off cleaned pan,cleaned oil pump screen ,oil pump gears and housing look good, did not measure clearances, after reinstalling oil pump
and pan,removed plug from side of block removed oil pump drive gear, installed electric drill on oil pump drive shaft spun pump with drill pressure went to about 35psi and stayed there.
Submitted: 2 years ago.
Category: BMW
Expert:  peterpete190 replied 2 years ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
Inspect for any sludge build up in the cylinder heads where the oil drains back down to the oil pan.I have seen oil sludge build up cause oil to stay at the top of the engine and not drain fast enough into the oil pan and cause this here.If an issue is found it will need to be cleaned to correct this fault here.
Thanks Pete
Customer: replied 2 years ago.
The head went to a machine shop where it was cleaned, pressure tested, resurfaced, valve guides replaced, head had to be reinstalled with a shim. This shop does very good work, never any problems before.
Expert:  peterpete190 replied 2 years ago.
This may be a bearing issue with the crank shaft bearings or cam shaft bearings.I have seen to much play in between the bearings and cam and crank that can cause this here.
Thanks Pete
Customer: replied 2 years ago.
When we put a electric drill on pump oil pressure was good about 35psi steady. Looks like a clearance problem would cause low pressure no matter what.
Expert:  peterpete190 replied 2 years ago.
The pump sounds to be o.k. but if there is a clearance issue with the bearings this can cause this type of fault here.
Thanks Pete