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Re: Oil Pressure Warning Light …please help! Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Wed, 7 Jan 2004 06:24:58
In Reply to: Oil Pressure Warning Light …please help!, August West, Tue, 6 Jan 2004 17:22:38 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Two reasons for the Oil Pressure warning light to come on- a fault in the warning light circuit, or low oil pressure. The first one is a nuisance; the second is very, very expensive.
Very low oil level can cause low oil pressure, because there isn't any oil in the sump to pick up. But unless you're leaking it big time, that's unlikely.
Oil pressure really is low- most likely a bad oil pressure valve. There is a valve down by the oil pump that helps regulate the oil pressure. If the valve spring gets weak or breaks, the valve can drop oil pressure pretty low. Oil pumps can fail, but they're pretty stout, so I doubt that's the problem. There could also be a blockage in the oil pickup. But I'd put my money on a bad valve spring.
If the oil pressure is fine, the warning light system is bad. The pressure switch is just a switch to ground, with a wire running to the dashboard light. Oil pressure switches do fail, and sometimes they fail ON. The solution is to replace the switch. If the wire to the switch contacts ground (just about anything metal on a car), the light will also come on. So a frayed wire, rubbing someplace will do it.
The very first thing the shop should do is stick an oil pressure gauge on the car and check the pressure. If the pressure is good, then the problem is most likely the switch. If the pressure is actually low, the pressure valve spring is the most likely suspect. Unfortunately, if the oil pressure has actually been very low for the 30 mile drive last night, and the drive to the shop this morning, then I fear the engine has been damaged.
Given the symptoms, I suspect you've got a bad oil pressure switch. This comes from two things - first, oil pressure switch failures aren't unheard of (I've had two fail like this). Second, if your oil pressure really was low, chances are good the engine would be rattling like a tin can full of BB's, making all sorts of racket. Possibly it wouldn't have made it as far as it has. So since it isn't dead or near dead, you're probably OK.
Without the right equipment, there isn't much you could have done last night. If the oil level is OK, (i.e. there is some on the dipstick), then the next step is to plumb an oil pressure gauge into the oil system and check the pressure. This isn't something most folks have lying around, and it isn't a trivial task. So nobody really could have given you much in the way of useful advice other than to appeal to the power of prayer.
However - if I ever see an oil light in a car, I IMMEDIATELY shut the engine down. If I'm on the highway, I'll get to the side of the road, but I won't try and make the exit. In a real low oil pressure situation, you can destroy an engine in a matter of seconds at engine speeds you see on a highway. The only exception I'll make is if I see a flickering oil light on a very hot day, and only at idle. And that's a sign to get an oil change immediately. But if the oil light comes on at anything over idle, ever, I immediately shut the engine down and have the car towed to someplace where I can get the oil pressure checked. Yes, that's a real pain, especially since the problem is more likely to be the warning light than really low oil pressure. But a new engine is not cheap, and a few tows (thanks, AAA!) are a lot cheaper than one blown engine.
I've seen, or personally know of 5 oil light indications with the car at speed. Not all Saabs. In two cases it was the oil light. In the other three, it was due to lack of oil - In my case, an engine mount broke and dropped the engine onto a suspension member, breaking the pan and causing a catastrophic oil loss. In another, it was a filler cap left off, and the oil splashed out. In the last, somebody just plain didn't add oil (Why should I put any in? I didn't take any out! - honest, that's the quote). In the three cases where it really was low oil pressure, the engines were toast. So I never take chances with the light.
posted by 192.249....
, Wed, 7 Jan 2004 06:24:58 <-- Viewing This Message
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