1999 BMW 3 series - bad oil pump?


#1

I have a 1999 3 series BMW, 115K, 5 speed, always used full synthetic oil, as did the previous owner. After a cold start, even at moderate/warm temperatures (65 degrees), for the first 2 - 3 minutes after the RPMs go over 1200 or 1300, I hear a noise from the motor, almost like a slight rattling/scraping sound of sorts, not very loud. The BMW dealer advised it is a known problem from new, and that the solution is a new oil pump. They advised that the repair is not necessary and to keep driving. My hunch is that the top of the motor is not being sufficiently lubricated after the cold start. I should further add that the car drives great, and I just took it on a 750 mile highway trip without any problems. The oil light always goes out, even on a cold day with a cold start, within 1 second after starting. Any thoughts? Thanks!


#2

You need to have someone put a mechanical oil pressure gauge on it and test the oil pressure at startup, and once the motor is warmed up. This will tell the story as to whether you need a new oil pump or not.

I’d advise you to do this soon, as engine damage may be occurring if you have low oil pressure.


#3

Have you checked on the BMW forums? Those folks are very active, if it’s a common problem it will have been discussed in detail.


#4

Hi Texases,

Thanks for your suggestion. Where are the BMW forums? Which one would you recommend?


#5

Google ‘BMW forums’ and you’ll find several. I guess I’d start with the BMWCCA forum, go from there. Yours is the “E46” internal BMW designation, there are even forums specific to it!


#6

I don’t subscribe to the bad oil pump theories very much but you have to look at it in the following manner. The oil pump is the first thing to see oil from the pan and if the pump is bad this means everything lubricated by it is being short changed lubricant-wise.

Also don’t put too much reliance into an oil pressure light. Most oil lights turn off at very low oil pressures (often in the 3-5 PSI range) and pressure that low is not going to protect an engine very well. It will have a short life.

Depending on the oil change regularity it’s also possible the engine is sludged up and the pickup screen in the oil pan is caked over to some degree.
I agree with oblivion; have the oil pressure checked with an external gauge as a first step.


#7

My quick look at one of the forums found no discussions…I wonder: how ‘common’ is this problem?


#8

If I remember correctly the oil change intervals recommended by BMW (and maybe part of their “free maintenance” program during the first 50k miles???) was something along the lines of 10-15k miles/1 year, etc.

This may go hand in hand with some of those infamous pics of oil sludged BMW engines.
My feeling is that the OP was given a line of BS by a service writer.


#9

I had the same problem with my '88 Ford a few months ago, low oil pressure, and top end noise. I pulled the oil pan off and removed the oil pump pickup tube and cleaned it good with brake cleaner, reassembled it and have had better oil pressure than I’ve had in years. This was on an engine with 517K miles. You could try putting a new oil filter on first, if it’s damaged or clogged you would get the same results. Hook up a mechanical gauge to the engine first, don’t rely on the idiot light. On most cars by the time the idiot light comes on the oil pressure is dangerously low.