e34 cold noise

[nariusb]

I can't isolate the loud wheeling/pumping noise comming from under the hood. It only happens first thing in the morning when stone cold. It's like the engine is trying to pump very very hard. Spots in 10-20 seconds.
Is this normal? Oil pump failing, trying to build up preasure?
Thanks a million!
Car is 1989 525i m20 engine. Water pump just done. Car runs well, just too hesitant from the stop. Gets better if warm.

[Kalevera]

If the oil pump wasn't giving enough pressure, the oil light would remain lit on the dash for a few seconds (or more) after startup. There's a documented issue on the M30 oil canisters seeping while sitting, therefore taking a little longer to provide full oil pressure on startup.

[632 Regal]

what oil are you running?

[nariusb]

Oil is uknown at the moment since I've bought the car a month ago. I am doing an oil change today. I'll flush the engine with Gunk engine cleaner for 5 min and I'll put in Mobil 1 Synthetic 0-w40. Hope that will help.
I wonder if anything else could cause that?

[632 Regal]

DO NOT FLUSH IT! just change it while the oil is hot.

[nariusb]

Thanks for the tip. I really wasn't sure about flushing. It would probably wreck the engine, woudn't it?

[632 Regal]

well, its not really a good thing, its usually a very very thin oil which sometimes can cause the bearings to run right against the bearing surfaces, and thing about the cam and lifters without lube! just change it hot and be done

I did the flush one time LONG ago and did quite a job on my grandfathers car, 27k on the clock and a big rattly crank and rod knock downstairs, wiped out the cam too. I didnt just let it idle though I went and drove it for about 5 miles and really tore that thing up.

[JonE]

Is the sound definately coming from the front of the engine compartment? Other possibilities might be the fan clutch (can be quite noisy when cold, like a big truck engine sound), or the alternator. Any other symptoms, slow starting engine, other electrical issues?

[shogun]

for allocating noise in the engine room. You can make one by yourself
-easiest is a large screwdriver
-cut a small pipe and attch some plastic part in the front (a filler cap and a cut off from the plastic bottle does fine)

-or do it 'high tech' with a mechanics stethoscope which costs around 15 $.
That is like HiFi for the backyard hack mechanic

[E34-520iSE]

Hi NariusB. It may be the belts going round the pulleys. Mine makes the same noise from cold and goes away in a short while. It puzzled me last year when I built the engine, so I decided to find out the noise source. I started the car, threw some water over the front of the engine to soak the belts and voila! The noise went away. I may have a slack belt somewhere but it hasn't shown itself over the last 15 months. The viscous coupling will also make the fan roar noisily for a bit but you should hear that noise die down as the fan slows.

Hope this helps!

Shaun