Oil pressure light stays on for some seconds

SamiA

SamiA

Member
Site Donor
Messages
34
Reaction score
38
Location
Finland
I found an advice in this forum saying:
"Both yellow-orange Oil Pressure & red E Charging System lights should illuminate when key is in position 1 & start. Both should go out within 2 seconds of engine running. "
Well, the oil pressure light in my car stays on for more than mentioned 2 seconds after engine has started. I'd say some 5 seconds. At least some seconds more that the charging light. I've owned the car only a bit more than a month. During that time I feel that the time for the oil pressure light to stay on has increased. But I'm not sure. It might also be that since the car was new to me I did not pay attention for the light to stay on.
The light stays on those mentioned some 5 seconds only during cold start. Once the engine is started at least ones, the light goes out with in a second or two during a restart.
My 1973 CSI coupe has an M90 engine.
So the question is should I be worried and/or what might be wrong if anything?
 
Is the oil filter housing the one that came with the M90? There is a drainback valve in the system that prevents the filter housing from draining back into the pan over time.
 
Not uncommon for the M30 M90 engines for the oil light to stay on a few seconds longer than you think is necessary. This is across the board of all the models. E3, E9, E12, E28.
Don't panic. It did go out right? Panic if it doesn't go out and turn off the key.... quickly.
 
Depends on ambient temperature at cold start & oil weight used. As long as the oil level is good & the light goes out.

It’s normal for the L to go out before the O
 
I think I would also consider the:
Grade of oil I guess it is reasonably cold in Finland at the moment, I recall seeing the sea frozen in Helsinki so I know it gets cool over there.
Condition of the oil filter.
I would change both oil and filter to a the standard in the operators manual for your climate.
 
You'll never know until you install and watch an oil pressure gage.

Some decade or two ago I put an oil pressure gage and sender in my 2002tii (roached it from a VW) and was quite surprised at the high cold idle oil pressure, and low hot idle pressure. Generally IIRC you want 10 psi increase for every 1,000 rpm. My pressure would max when the oil pressure relief valve opened, as designed. A neighbor had a souped-up air-cooled VW when it was common to install external oil filters with a larger oil pump - he reportedly blew off the filter if he revved it while cold. A little pressure is good, too much is too much!

As stated above (all good information) you don't want flicker at warm idle, and your actual pressure depends on oil viscosity, viscosity index (change in viscosity with temperature) and the condition of your oil pump, crank and rod bearings; but I think the most likely item for investigation based on your description is the drainback valve.
 
Buy a cheap mechanical oil pressure gauge and temporarily install it where the warning light sender is now. Tape the gauge itself under the windshield wiper for a day or 2, see what your oil pressure ACTUALLY is...and THEN decide what to worry about. Cost you $20 and take 20 mins.

And the drain back thing.
 
Thank you all calming me down.

Once the oil pressure light goes out, it stays out. It does not flicker in and out. Not even while the engine is idling.
About the drain valve in the oil filter housing: I do not know whether the filter housing is original for my M90 engine. To educate myself I did try read about the subject more from the manual I have found some day, maybe from this forum:
1601547525333.png


It seems to me there is not such valve in the M30 engine:
1601547602796.png


I tried to find similar manual with M90 engine, without success.

Another thing came to my mind: the idling speed. Just after cold start the idling speed of the engine is rather low less, than 1000rpm. While the one for warmed up engine is actually rather high ~1500rpm. That might also have an influence: the low idle for the light to stay on and then on the other hand the high to stay out.

And by the way, it is not that cold yet in Finland. Right now the outside temperature is some 16C/60F. But I can see the cold weather coming, right now the yellow, red and orange leaves are falling from the birches.
 
I was once tasked with a 4 1/2 hour trip down to Helsinki to meet my wife but had an M5 and 3 hours to do it in. I fell in love with the landscape. The arrow straight earthen causeways through bogs and the birch/larch trees in their June foliage. Awesome!
DSCF4470.JPG
 
You must log in or register to reply here.
Back
Top