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Oil Pressure light comes ON, only when idling

I drive a 1991 Toyota Corolla LX with 193K miles and NO I haven't had any acceleration problems yet.

My problem is that after 15 mins or so of driving around, the Oil Pressure light comes on but only when idling. Such conditions include

- When waiting at a traffic light

- A little before coming to stop at a traffic light when I have released the gas pedal.



Is this serious enough for me to stop driving the car ? I took it to a repair shop and they said it will cost me $40 to do an oil pressure check, which I have postponed for the moment.

Help please ?
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Comments

  • edited March 2010
    Oh. Also about the above problem. after the oil pressure light comes on, it goes away as soon as I accelerate just a little bit. This works even if I am on Neutral and stationary.

    Did I mention I am a student, and $50 means I need to work around my budget !
  • edited March 2010
    With this many miles, I would get it tested. If you are very lucky, the problem is a bad sensor, but this is unlikely. Your symptoms suggest worn out main and rod bearings. This can sometimes be cured with a new set of standard bearings, but only if the wear is almost all on the bearings, and not on the crank journals. Otherwise you are looking a having tghe crank turned and new bearings at a minimum. Get the oil pressure test done, but expect them to have to pull the pan and test the bearings for excessive wear. You can keep driving it, but it wont get better by itself, it will only get worse.
  • edited March 2010
    First check your dipstick. Is there enough oil and how does it look? How does it feel? If the oil is diluted with gasoline don't re-start it until the oil is changed.
  • edited March 2010
    Ignoramous posted an excellent description. I agree with his postulate.

    Since you're on a very tight budget, let me suggest an oil pressure check gage (kit) at the parts store, along with a Haynes repair manual. This is an easy test, it'll be clearly described in the Haynes manual and in the test gage instructions, and it'll save you money over going to a shop. It'll also get you started in doing your own maintenance, which will save you tons of cash.

    If Ignoramous is right, and I'll bet he is, that'll mean the engine is just basically worn out. I personally would be reluctant to spend money rebuilding it for a Corolla that age. You can try some higher weight oil, like going from a 10W30 to perhaps a 20W40, it might help, might not. Some recommend against this due to concerns with the top end (valvetrain) lubrication, but on an engine this worn I don't see that as a major concern.
  • edited March 2010
    Any noise accompanying this flashing light? How's the consumption. We often construct a dinosaur's head from a pig's tooth here, so let's really get the picture a bit more into focus before writing this off.

    I already know you're not going to do any internal engine work. You'll find another beater.

    If you want the cheapest approach, grab heavier oil. NO - IT'S NOT THE PREFERRED WAY TO NAIL THIS DOWN, but given the immutable physics of your wallet, outside of a bad sender, you're screwed anyway.

    If you use a 30 weight, go to a 40 weight. Escalate as needed.

    You're in tactical mode. No strategy allowed. Good luck.

  • edited March 2010
    This just means that with 193000 miles tour bearings are worn and at idle the oil flows through them too quickly to maintain enough pressure to keep the light off. As long as the light goes off when you step on the gas you have nothing to worry about, you probably have many more miles in this engine. I wouldn't however try any top speed runs.
  • edited March 2010
    An oil pressure test should be checks of the oil pressure at idle, at 1,000 rpm, at 2,000 rpm, and at 3,000 rpm. YOU could do these checks with a $15 oil pressure test gauge.
    If the oil pressure is OK at rpms above idle, it shows that the oil pump is up to the task; though, the engine may be rather worn. If it is OK at the higher rpms, you can nurse some more time out of the engine.
  • edited March 2010
    You could buy one of these, change it out, and hope for the best if you don't want to have an oil pressure test done. This is an easy cheap swap.

    http://www.autozone.com/autozone/catalog/parts/partsProduct.jsp?itemIdentifier=123869_0_0_4316,5835&skuDescription=Duralast+/+Oil+Pressure+Switch&brandName=Duralast&displayName=Oil+Pressure+Switch&categoryNValue=&sortType=&store=505&isSearchByPartNumber=&fromWhere=&fromString=&counter=1&itemId=134-0&navValue=15300134&filterByKeyWord=&productId=123869&searchText=&categoryDisplayName=External+Engine&parentId=53-0

    If the light still flashes on after this then the crankshaft bearings are probably worn out and this means a new engine. As a stop gap measure increase the viscosity of the engine oil; meaning a heavier weight oil.
  • edited March 2010
    The Auto Zone Web site (of the above link) states that they don't have the oil pressure switch. Their isn't a photo, either. Try another store.
  • edited March 2010
    Wow! Thanks for the super fast and extremely helpful response. So, I am getting a bad feeling about this whole thing now.
    Anyway, just to clarify geeaea's question - No there is no other noise accompanying this light coming on or going off. So far as I can tell there is nothing different about the operation of the car (gas consumption, acceleration, etc.)
    I spoke to the repair guy again and he said something similar. He said he wants to do the oil-pressure check to figure out if it is just because of a bad sensor switch or the engine wearing out.
    The way I understand this now is I have two options,
    1.) Get the oil pressure check done, and hope it is just a bad sensor.
    2.) Get the oil pressure check done, and if it involves a worn out engine...then upgrade to a higher viscosity oil and hope that the engine won't quit on me.

    Anyway, I use this car for getting around town and going to school. That is about approx 20 miles of driving in the day. I usually go to New Jersey from Ohio (~500 miles) twice a year, but I guess I can't take my trusted car anymore...(sigh!)
This discussion has been closed.