Tim_944

This is a late 85.5 944, all of a sudden the car now idles at 1 bar oil pressure when warmed up and the oilp reassure light comes on at idle and when you rev it, it goes away and goes back to around 3 bar. This is down from the usual 2 bar idle and 4-5 bar when reved.


Here are the facts:

- haven't recently worked on it so I have no messed with the crank bolt tq

-last year I replaced a leaking oil pressure sending unit with a new FAE aftermarket one and it has been working great till now but i'm thinking maybe it is failing.

-the car has high milliage prob over 300k kms but 2 years ago I replaced the rod bearings as preventative maintenance and also replaced the oil pickup tube.


-the oil pressure relief valve is the old 3 piece and it failed once before years ago and i got Zero oil pressure at idle and with rev. The failure was actually the metal sleeve or bore in the block that the piston rides in, it had come loose form the block. this was many years ago and it has been fine since then.

-i was told to update my old 3 piece style relief valve to the new style but i don't' see how the old style valve can fail, unless the spring breaks or gets weak over time?

when i start the car there is 5 bar oil pressure but once it warms up idles only at 1 bar (down from 2 bar before), and only goes up to 3 bar when reved down from 4-5 bar. If the oprv was malfunctioning i think i would have low pressure when cold also. i'm thinking a failing sending unit or something else.

thomasmryan

I would try a mechanical gauge to see if your sending unit is accurate or another unit and compare readings.

Fresh oil? Be sure you are not getting fuel into the sump. If you have any orings for the pressure release valve, I would remove it for inspection also.

Tim_944

where would you get a mechanical gauge from? and also how do I check for fuel in the oil. the oil is fairly new and i've been using 15w50 mobil one for years.

i might go and buy a new pressure sender and see if that is the issue.

my oil pressure relief valve is the old 3 piece style with a piston and a spring there are no O rings.

Auto_Werks 3.6

how does the oil look? water in the oil from failed head gasket or oil cooler seals will reduce viscosity and oil pressure. worth looking into

John_AZ

Buy the updated 1 piece OPRV used if possible, new is $$$
Post a WTB.

http://www.ebay.com/itm/PORSCHE-944-...d2958a&vxp=mtr

Is the "sleeve" you repaired a press in item or bonded in some manner?

J_AZ

konakat

The OPRV could be sticking open a little, which only becomes a problem once the oil is thinner. Generally the failure mode is the piston starts catching on the inside of the bore and doesn't fully extend anymore.

chuckytheczech