Oil pressure ok?

winddance@att.n · 12-09-2003, 04:06 PM

86 944
New sending unit. Wired correctly. Gauge reads 0 before startup. 4.5 when started and at idle. 5 at cruise (but not the pegged out 5). The gauge never goes below 4. Idiot light only on before start, doesn't flicker. Minimal oil leaks, no valve chatter. Do I need to worry? Could the oil pressure relief valve cause this? Bad engine ground? Faulty wire to sending unit? Where is the best plce to look for a culprit? Can I just rely on light? Don't want to buy an oil gauge just to test it, but will if I have to. Do the standard fit all jc whitney oil pressure gauges fit on a porsche?

cruzermusic · 12-09-2003, 06:09 PM

hey,,, i have a 924s 1988.. my press. gauge reads 4.5 a the slightest press on the gas....on idle... 2.5 ... ckeck your ground again....something not right having it stuck on 4.5...

ps // my idiot light works great ,,,i get 1/2 quart, low the light come on,,,, but if the bulb burns out???? i think another light will come on.....bad news......dip your stick every 2 months to be sure...

ae1969 · 12-09-2003, 06:39 PM

Uhmmm sounds normal. If your relief valve was not working you would have much worse readings than those.

Which weight of oil are you using, this also affects the readings......

Manute · 12-09-2003, 10:30 PM

Quote:

Originally posted by cruzermusic
ps // my idiot light works great ,,,i get 1/2 quart, low the light come on,,,, but if the bulb burns out???? i think another light will come on.....bad news......dip your stick every 2 months to be sure...

I think we don´t have that in the early turbos,am I correct?

Yes,check oil weight,with 5W50 and a bit cold temperature outside,i´m 3 at idle, so with a thicker oil i think 4 bar or so is acceptable.

Cebu · 12-10-2003, 04:15 AM

My experience for a problem of high oil pressure was to remove clean and reinstall the Oil Pressure Regulator(OPR). There was a small piece of rubber from the Oil Filter sealing ring caught in the OPR. I went through three(3) oil pressure sending units before findng the fix. Use a mirror and insure there is no foreign material in the OPR port.

bearone2 · 12-10-2003, 07:56 AM

1/2 quart low shouldn't make the oil light come on. the light is a function of low oil pressure probably 1/2 to 1 bar makes the light come on because of insufficient oil pressure because of engine wear problems or low on oil quantity.

winddance@att.n · 12-10-2003, 02:14 PM

ae1969: Thanks! I use 20-50, but never drive it when it gets cold out because of the salt here in MN. I usually use synthetic during the driving season, but use reg oil during the winter. Right now my little honey is sitting in the barn with my fishing boat, tractor and llamas. Hey, if you think this sounds normal I'm happy. Not often someone says the word normal in my presence.

ae1969 · 12-10-2003, 02:18 PM

Well.... 20W-50 sounds 'normal'..... for the readings you have for MN. Wait until summer when you will probably see 3bars at idle with that weight of oil.

If you would of had the wires crossed it normally stays pegged.

hehehe and I use the term "normal" loosely around here with the characters we have

AaronM · 12-10-2003, 02:22 PM

Quote:

Originally posted by bearone2
1/2 quart low shouldn't make the oil light come on. the light is a function of low oil pressure probably 1/2 to 1 bar makes the light come on because of insufficient oil pressure because of engine wear problems or low on oil quantity.

It also can be triggered by low oil level on later cars.

Aaron

SoCal Driver · SoCal Driver's Garage

Interesting. Just did my third oil change after installing a used 86 engine that had sat for almost four years. Noisy lifters. Did the ATF thing twice.

Guess the third time was the charm as I now have no noise and lots higher oil pressure at warm idle. Was 1.5 5o 2. Now around 4.

Used Mobile One 10-40.

bearone2 · 12-10-2003, 02:36 PM

atf, talk to me as i have some noisy lifters.

SoCal Driver · SoCal Driver's Garage

Add a half to full quart of ATF for about 500 miles before the oil change.

First time was half. Second time was full quart. Seems to have worked. Guess I should give it a week.

bearone2 · 12-10-2003, 02:52 PM

how far you go between oil changes?

give what a week?

why 1/2 then 1 qt. does it hurt to start with the 1 qt?

turbohead7 · 12-10-2003, 03:24 PM

Most 944's drop to around 1.5-2.5bar when warm. The oil pressure relief valve limits high oil pressure above 5 bar, it shouldn't affect your lower readings much. Oil viscosity shouldn't affect the guage reading much either as I've eperimented with different weights on different cars. If this is a new thing, You may have a small restriction somewhere in an oil passage, this will create an unusually high reading. 4.5 bar at idle when warm is unusual. Fully synthetic oil such as Mobil One does wonders for cleaning engines. But before going nuts thinking about the engine, oil pressure testers can be bought for about $50; finding out whether the reading is accurate is crucial to a proper diagnosis. Your problem could also be with the wiring. Lastly, I've heard of aftermarket filters causing strange oil pressure readings, have not seen this myself yet. Many people, and filter manufacturers, don't know that Porsche 944 filters have a specially designed pressure relief valve and spring. Factory filters are best, Mahle is a close second.

winddance@att.n · 12-11-2003, 06:02 AM

Turbohead: I bet you are right. Just using a fram filter. By the way it is at 4-5 summer or winter, warm or cold. I will chekc the grounds then change the filter to m=oem. if that doesn't work I will clean the oil press reg. When I bought the car the oil press gauge was maxed out due to a bad sending unit. Could this have semi-fried my gauge?

Cebu · 12-11-2003, 08:44 AM

As Turbohead mentioned..I too had to replace the Oil Pressure Sending wiring from beneatd the AFM down to the sending unit. the wires had become brittle and was shorting inside the conduit. As in a previous reply I was experiencing hig oil pressure indication. I am using 20w40 and indicates 4.5 cold and 2.5 at idle, warm engine.

winddance@att.n · 12-11-2003, 10:32 AM

Cebu, thanks! I will replace the wire. Can't get the car out of my ranch til spring anyways.

SoCal Driver · SoCal Driver's Garage

Just had a longer session in driving with Mobile One. I swear that there is better performance.

What else can I expect with synthetic?

AaronM · 12-11-2003, 06:12 PM

Quote:

Originally posted by winddance@att.n
Turbohead: I bet you are right. Just using a fram filter. By the way it is at 4-5 summer or winter, warm or cold. I will chekc the grounds then change the filter to m=oem. if that doesn't work I will clean the oil press reg. When I bought the car the oil press gauge was maxed out due to a bad sending unit. Could this have semi-fried my gauge?

GAH! Don't use Fram! You're making your car cry!

Fram uses cardboard endcaps which are prone to disintegrating or exploding and the anti-drainback valves leak profusely.

Aaron

turbohead7 · 12-11-2003, 07:16 PM

A sidenote for all you synthetic users: WARNING, Beware of so called "synthetic" oils. Many petrolatums distribute oil labeled as synthetic when in fact it is natural oil which is only modified or blended. Mobil is one of the few who actually produces a 100% fully synthetic motor oil as labeled on the bottle. Why else would Porsche fill every car since new from 94 and up? As if I had to tell you guys Mobil 1 is the best oil on earth! I have seen first hand the internals of high mileage engines which use this stuff. They are as clean as the day they were built with no sludgy build up that you get with natural oils, regardless of ritualistic oil changes. It can also be used to clean any older engine with this nasty buildup. And it can be mixed with, or used in place of your current oil. Of course, always use thiker oil on older engines, especially leaky ones.