Oil Pressure light comes on when idling [Archive] - SaabCentral Forums

: Oil Pressure light comes on when idling


jackforester
5th February 2007, 03:46 PM
When my car is warm and idling, my oil pressure light comes on, but as soon as my RPMs hit about 1200 it goes off. This started happening after we got a real cold weather front move in, so I think it may be some kind of line leak or something, but I don't know. It doesn't make any sound, it just comes on. My car idles at about 1000RPM, so when it goes up just 200 RPM it goes off. I have to figure it out quick, becuase I have to drive my car daily, and I'm quite nervous driving it with the oil pressure light coming on.

Well, I assume its the oil pressure light, it's the oil light that is in the engine bay on the dash (the little car that shows if doors are open and whatnot).

Anyone know of a Vacuum line that may be cracked, or something along those lines?

boon94
5th February 2007, 05:04 PM
Did you check your oil level? Is your oil too thick for winter temperature? Does the light go away permanently once the engine has heated to operating temperature? (after 20 minutes of driving).

Do you have the v6? I remember something about the v6 having more oil problems than others because of the timing belt was it? Gar i cant remember. Some type of screen that scoops up the oil gets clogged and doesnt work properly or something like that.

Someone else will elaborate, i dont know too much but want to see what happens.

djtaylor
5th February 2007, 05:05 PM
Obvious answer would be that it's coming on because of low oil pressure.

It could be a worn pump, relief valve sticking maybe, blocked filter.

Try a filter and oil change but without a guage on the system, you're not going to know what the actual oil pressure is.

One of my old cars used to have the oil pressure switch activate at 2 lb psi which is about as useful as a chocolate teapot. Light illuminting pretty much indicated that the engine had just seized or in reality because the oil was low when I was taking a tight right hand bend and the oil sloshed to the left away from the switch.

Stick a guage on it if you still have problems after the filter and oil change.

David.

PetesGriffon
5th February 2007, 05:24 PM
I second what the good gentleman have said and add another step.

Check the oil level to make sure you actually have enough. Change the oil but first add some seafoam to the crankcase and run it that way for 10-20 minutes till the oil is at operating temperature and then some. If anything is clogged, it will become unclogged.

If the oil pressure was truly low, you would hear a lot of noise coming from the engine.

When I stripped my oil line bolt and it was spraying oil with little pressure in the motor itself, there was a massive amount of ticking and squealing coming from the motor.

Maybe just the sensor needs a clean and then the seafoam will take care of it.

jackforester
5th February 2007, 06:02 PM
Wow, thanks for the quick response guys!

My oil level is fine, it's right below the Max line.

Boon, the light doesn't come on UNTIL my car is at operating temperature, if it is cold it doesn't come on, just once it gets totally warmed up. The engine isn't making any odd noises as far as I can tell, I haven't heard any squealing or ticks.

I guess I could have given a little more info, my car is a 92 4Cyl 9000. It's going to be this weekend until I can have a look at it, or do anything. But I have to make a 1 hour drive back home to do so, as I'm at college and I have absolutely no tools to even begin to do anything but check levels.

It just doesn't make sense to me why it only comes on when I'm idling, the only thing that I thought is maybe a hose, or my oil pump wearing out.

Thanks for the help guys, I'm going to put some seafoam into it this weekend probably, and then probably change the oil, thanks again!

KevinC
5th February 2007, 06:40 PM
How many miles?

My first car was a big-block Ford V8, and near the end of our partnership at 155k miles it did exactly what you describe. It was simply excessive bearing wear and a wearing oil pump, lack of supply and excess draining when hot at low rpms. Worked fine like this for many miles and kept running smooth, but the end was drawing near is the indication. Not necessarily real soon though.

PetesGriffon
5th February 2007, 09:57 PM
Multiweight Oil thickens as it heats up...this might explain.

Cant hurt to do a crankcase flush.

Also try running a good synthetic. It's thinner even at temperature and might prevent the light (and the underlying pressure problem)

Marrk
6th February 2007, 05:20 AM
Sorry to be a a pessimist here, but IMO I reckon the big end or main bearings are worn and the oil pressure is being lost through the excess clearance. The oil pumps are totally bulletproof even after tons of metal have gone thru them. Its rare for a pressure switch to suddenly change its setpoint, the fact that the oil light comes on once the oil has warmed up is a classic sign of worn bearings somewhere in the engine. The engine will still sound sweet, mine did, went down the road of new oil, filter, switch, oil thermostat etc etc. Big ends let go about 1000 miles later.
If I was you I'd drop the sump and check the main and big end bearings....try all the above first except the seafoam as if your sump and engine is full of sludge or crude this will loosen it and cause more problems than it is worth unless you remove the sump to ensure the suction filter is clean and not blocked by seafoam removed debris.....not all of it comes out in the oil change.

HAL9000
6th February 2007, 12:52 PM
Sorry to be a a pessimist here, but IMO I reckon the big end or main bearings are worn and the oil pressure is being lost through the excess clearance.

I second this. The engine is practically a wreck and needs total teardown. You will probably need new rods and the crank is very likely to have suffered too and is in need of grinding to first undersize.

As for the reason, my guess goes to worn out balance shaft gear at the end of the crankshaft.

jackforester
7th February 2007, 06:52 PM
I am going to have a look at it this weekend, hopefully it doesnt crap out on me, I can't afford another car right now, so if it does i'm completely screwed.

jackforester
9th February 2007, 02:36 PM
Anyone know what the rough cost may be to have the engine bearings replaced?

KevinC
9th February 2007, 03:16 PM
Have you tried real thick/heavy engine oil such as 50 weight, and maybe a can of 'miracle fix' additive for tired engines?

jackforester
9th February 2007, 05:00 PM
No, I haven't tried a heavy weight oil, nor any additives.

However, I just made the hour long drive back home, and the light didn't come on once, kind of weird. I'm going to keep watching it, It's due for an oil change soon anyway, so I will probably change the oil this weekend, so I may add something to it when I do that.

Marrk
12th February 2007, 07:49 AM
What you need to do is drain the oil into a clear plastic container. Let it settle for 30 minutes then decant into another container. Leave the dregs in the clear container and shine a torch underneath, this will identify any metals that might indicate bearings failing. Silver bits are the 'white' metal, lots of this is bad and sign of failing bearings, copper bits shows the bearings are totally gone and its terminal. Do not get a garage to do it as they do not check what has come out in the oil.

jackforester
12th February 2007, 12:16 PM
I didn't get a chance to change my oil this weekend as I was swamped with housework and some other things, but the light did not come on when I drove it this weekend. I still have to change my oil, but it has to wait a week, but I'm not going to be driving it at all through this week, just once on friday to get home.