Oil pressure problem...

[skandalis447]

Hello there...After 63000miles of a C2 MY02 my brother owns,oil pressure started behaving strange...when hot and idling the pressure started dropping below 1bar...and after a heavy traffic it went below 0,5 bar and pressure warning light came up...i replaced sender unit(VDO) without any success...same results...when hot and idling it stays below 0,5bar...He uses only mobil 1 0-40 current oil has run 3000miles...Also oil level has weird behaviour...when cold it is two line below max...But when hot(and after warning for oil pressure) it goes over max....!!!Engine has always ran fine,no check engine lights,could it be a bad oil/air seperator?Any ideas?

[Loren]

The oil level sensor behavior is normal - you do not want to be at the full or over full mark. Especially if you track the car or have spirited drives.

You don't talk about outside air temperature where does he live - what are the temperatures when he sees this?

5W-50 is also approved.

[skandalis447]

Thank you Loren...Is it ok for oil level to be two lines below max when cold and one above max when hot?all times now when hot it was below cold level...Outside temp is very hot...37-40 celcious...

[Loren]

How do you know it is above max hot? Isn't it just "full".

What is the coolant temp when air temp is 37 40 C?

[skandalis447]

Well...i measure oil cold(with the dipstick) and find it just below full...when i measure it again hot(after i switch off engine) it is a little higher than max...weird isnt it?coolant temp is at the end of 0...I worry if it is something major...

[perryinva]

Proper level is when oil is cold and car level. Oil pump could be going. SInce it is repeatable, it needs to go to a good technician and have oil pressure measured when idling. Period.

[skandalis447]

On this car (C2) in order to change oil pump do you have to remove motor?Or can be done with motor in place?

[1999Porsche911]

Check for broken oil pressure spring on the oil pump. Don't do anything drastic like changing the oil pump until you get a real mechanical oil pressure test.

[wvicary]

The oil pressure must be verified with a mechanical gauge. I assume your hot idle speed is correct and there are no signs of any oil contamination from coolant or fuel.

[skandalis447]

The oil pressure must be verified with a mechanical gauge. I assume your hot idle speed is correct and there are no signs of any oil contamination from coolant or fuel.

Thank you for your reply...My idle speed is correct...PIWIS reads 710-730rpm...Coolant is clean and level is ok...i have not add coolant for months now...How can i tell about fuel contamination?Engine runs like new...No smoke at all(even at start up)oil was changed every 7500km with mobil1 0-40 and in the meanwhile no more than 800gr of oil was added...I will change oil and filter Monday to check the oil...and to replace it with 10-50...Also when i replaced pressure valve i did no clean the contacts...i ll clean them and check again...After that?Could it be a faulty dash meter?This engine has an oil pan,so i assume oil pump can be removed easily...(not like 996TT engine)Also what about the possibility of failed air/oil seperator?

[RFM]

Do what 1999Porsche911 suggest, check the pressure relief valve spring first, i have seen once in a while a M96 with a broken spring, a second point to look at is the oil filter holder valve system, which you can find on the bottom of the filter holder, the symptoms are for both issues too low oil pressure. The pressure relief valve is easy to find and to remove on the rear of the engine.

[skandalis447]

Do what 1999Porsche911 suggest, check the pressure relief valve spring first, i have seen once in a while a M96 with a broken spring, a second point to look at is the oil filter holder valve system, which you can find on the bottom of the filter holder, the symptoms are for both issues too low oil pressure. The pressure relief valve is easy to find and to remove on the rear of the engine.

thank you...tomorrow i will change oil and filter and try to find what the problem is...If the engine had a major problem,shoud i have any warnings?check engine,rattle,etc?

[RFM]

I would not wait for an engine rattle and a check engine light, since the car already suffers with a oil pressure warning.

[skandalis447]

Guys...problem solved...Well actually it seems that there was no problem with the engine...As i stated i replaced VDO sender unit and then started worrying about engine internal damage...Finally i added a mechanical gauge to measure oil pressure and to my surprise it is 1,5bar at idle even very hot...Also when i rev the car at 3000rpm it goes at 4,8 to 5 bar while in dash it shows only 3,7bar...So obviously there is something wrong with wires or gauge of oil pressure...What a relief to find out engine is ok...

[RFM]

Well, this is a problem less, hope you can find the cause.