Question is pertaining to a 1991 audi 90 allowed my oil level to drop way to low at which point the 'alarm' for low oil pressure began to sound. unfortunately, even after toping up the oil and cycling it thru the engine, the high pitched scream of the 'alarm' is still continuously sounding. the sound is coming from behind the dash. we pulled the dash and unpluged the wire but unfortunately many others are tied into the same plug. pulling the plug 'disconnected' every sensor/gauge on the left side of the dash but did stop the warning sound. unfortunately, it took only a matter of miles before a new warning sound started to continually ring. assuming i need to plug the plug we removed back into the dash, but how do i stop the warning sound from continuously ringing?

These symptoms usually mean you have a failed main or big end bearing in the engine. If it gets more noticeable as the engine warms up, that type of failure is even more likely. If the knocking varies with revs it is more likely a big end. You may be able to get the sump off without pulling out the engine, and do an inspection.

I can't think what the brake warning light would have to do with all that.

Maybe the sensor is bad...?

The gauge indicates pressure, not oil level. Sounds like worn bearings or pump. lifters getting louder indicate starving from low pressure as well.

94 Audi A80 2.6 liter

Coolant from the car's cooling system will generally escape into the oil passages (and into the cylinders) under pressure when you have a blown head gasket on your engine. You will also notice that you will need to be topping up the coolant level.

This is not a reliable model and the head gaskets on these engines are prone to failure if the cooling system is not completely flushed out and new coolant added at least every 2 years. The head gaskets will also blow if the car has been operated when the engine is overheated - such as when overheating is caused by allowing the coolant level to drop too low.

In your case the symptoms you have described do point to a blown head gasket. If you inspect the coolant in your cooling system when it is cold you will probably also see evidence of oil in the coolant fluid.

You need to get the car to a reputable audi specialist, who is familiar with the problems with these engines, to check it out for you.
If you have a blown head gasket, as it appears, the repair costs will be quite expensive as are most mechanical repairs on German cars.

Sean

If the oil light is on, Don't drive your car until you've checked the oil level .
The oil light is an indicator that warns you when the oil level has dropped to an unsafe level and will not allow proper oil flow thru the motor because the oil pressure is dropping.

Don't take a chance! Check the oil level. Make sure it's between the full and add 1 quart line. If you don't see anything on the dipstick, it's really low... If you run your car with low oil, you're going to freeze up the motor.

If the oil level is ok and the oil light is still on, have the pressure sender checked to make sure there's proper oil pressure. The light will stay on if there's a problem..

sounds like a faulty oil level sensor i,v replaced them in the past you need to get it checked first because the sensors aren,t cheap

Worn oil pump or cam brgs. Noticed the oil change, what about the oil filter?The oil filter has a bypass in it that will allow unfiltered oil to get past the oil filter if it plugs up. What is your mileage now and how was your maintenance habits? Good Luck. Remember, your cam brgs are the first point of resistance that control your oil pressure, not your rods or mains

sounds like low oil pressure

First have your oil level checked and make sure that it is at the right level. If not that's your problem, if your level is good you may have a bad oil pressure switch. This can be checked by using a oil pressure guage. If switch is bad replace and solve the problem. However if your vehicle has alot of wear and tear on he engine and you were using 20w-50 oil and it was replaced with 5w-30 that oil may be too "light" for the vehicle and you would get a low oil pressure reading. Good Luck

Have you made sure the oil level is OK? If it is, you may have a faulty sending unit or you may have oil sludge blocking the pickup for the sender.

If the level is OK, get a can of Seafoam (parts store, Walmart), and pour half the can into the oil. Drive 50-60 miles, then come home, add the other half of the can, let it idle for 10 minutes or so, and then change the oil. Seafoam is really good at breaking down sludge, and if that's the cause of your problem, it should fix it. Make sure you change the oil filter too.

Try that out and see if it helps. If not, you may want to look at a new pressure sending unit - if it's flaky it won't matter how much oil you have in the car - it'll still give false readings.