Kevinmacd

Here is someting crazy I noticed after changing my oil to 5W-50 M1. Just might be coincidence. If I am cruising at 2K, & I step on the throttle a little bit, the oil pressure guage goes for a little over 4 bars, quickly drops to just above 3.5 bars and settles out to the above 4 bars as would be expected. Oil is full, and when just cruising it stays steady. Seems to only happen around 2K on the tach. Seems to me that since this is a dry sump engine and oil pressure is a direct relation to engine speed that the oil pressure should either stay steady or rise slightly. Someone told me that these cars have oil pressure sending units that can act funny! so what do you guys think?

Macster

Think that's the sending unit acting funny. I see something similar from my 03 Turbo's oil pressure gage. Brought it to the tech's attention and I don't remember his exact words but seems to be a rather common fault and he may have said something about taking care of at some time when I bring the car for something else. So far I've not bothered to have it taken care of. But when I take the car in for the clutch accumulator I'll remember to bring it up and see if I can't get it taken care of.

In your car's case, absent any other signs of low oil pressure -- and any others signs of low oil pressure generally come too late to save the engine -- I'd say the bounce is nothing serious.

Also, read the owners manual. Mine's not handy but I believe there is a low oil pressure warning light in the dash that should it come on or flash signals oil pressure is dangerously low. If I'm right, and if that light's not on/flashing, the oil pressure gage bouncing about is nothing more than a goofy sender or gage.

The oil pump is a gear pump which is driven directly by the engine and oil pressure from the oil pump can't just dip and rise that quickly. Gear oil pumps are known for their high output, high pressure, and constant pressure at constant speed. The slight variation in engine speed is not enough to cause the oil pressure to dip and rise over that short of time period.

Sincerely,

Macster.

Kevinmacd

I have no indication the oil pressure is faulty. I agree it must be the sender, maybe when changing the oil some small debris got dislodged. Thanks for the response!

Macster

Could be wrong but I don't believe debris is the answer. Otherwise over time enough debris would collect to completely block any oil pressure to the sensor/sender.

My belief is that just a rather crummy sensor/sender or gage/display is to blame.

Sincerely,

Macster.

kezcapt

The sender is on the top of the engine and the terminals get corroded. Mine were developing an intermittent contact so I took the leads off, cleaned them bright, and reassembled with aviation grade corrosion block (blue stuff, common now in regular stores). That fixed it for me. The bad ground was causing a faulty signal; re-ground the signal add a corrosion block you are good to go. I think it was already mentioned but just remember this system has 2 monitors; the light on one sender, and the gauge on another. Always use caution with oil pressure variations but if both systems are warning insufficient oil pressure shut it down! your owners manual a a description of the system design. Good Luck.

Rob

Kevinmacd

Thanks checked the connections, they are a nice brass color and the terminals look good. I am convinced there is no oil problem, especially when really pushing the car, with 5w-50 the car idles with almost 2 bars, and pushinfg it 4.75 bars. The bounce only happens at 2K when in 4th or 5th and you hit the throttle a little bit, it bounces from over 4 bars to just below 4 bars, then back and steadies and doesn' do it all the time.

Last930

My oil pressure gauge bounces around a bit also; I don't worry about it.

Macster

Thanks.

That's a very good bit of info. When I have a chance I'll find the sender and disconnect it and do as you suggest.

The oil pressure gage bounce/jumpiness is not severe but it is out of character and I would prefer it to not bounce/jump about.

Sincerely,

Macster.

roadsession

Did you resolve this?

Macster

Uh, no. Last year and all of this year has been a real busy time for me with a family member who has been seriiously ill for some time now (this last incident has seen her in the hospital since Jan of this year and she has a month more to go before I think she'll be discharged) and dealing with elderly parents and then there's always 25 hours of work to do per day.

Just the other day though, I did try to force the oil pressure to move about by accelerating at various rpms because some have suggested the rise then dip then rise again is the VarioCam Plus system taking oil/pressure away but I was unable to see any pattern to the movment of the gage needle and rpms and throttle.

A Tip might be easier or the better car to try this on since acceleration from the lower rpm ranges is smoother than with a manual.

The Turbo is due for an oil/filter service soon. The odometer is coming up on 100K miles and that's oil/filter change time (every 5K miles). If I can remember I'll speak with the techs about getting that jump oil pressure gage addressed, provided it doesn't cost an arm and leg.

Sincerely,

Macster.

Kevinmacd

Try bringing the engine to around 2200rpm and hit the accelerator. It doesn't happen over 2800rpm. It bounces quickly.