Service engine soon

[krazyken2]

I have just recently serviced the engine, and the light comes on when the car is warm, sometimes goes out, then back on! But I have noticed the oil pressure drops when the light comes on! Is this probably the oil sencor is defective??? Any help is appreciated!!

Thanks

KK

PS I do not know how to do a diagnostic on this car!

[GTP Dad]

Welcome to AF! First of all which engine light comes on? If it is the oil light you may have a problem so I wouldn't run the car. If it is the check engine light you need to have it diagnosed by using a scanner to read the codes in the computer. Since you live in Canada you may have trouble getting it scanned unless you have a friend with a scanner or you can take to a garage and get it diagnosed. If you find out the code post it here and we will help you figure out the problem.

[krazyken2]

Thanks for the reply!

The car is a 1990 Olds 98 Regency Broughm, it has the DIS.. The light that comes on is the (Service Engine Soon) light!

The car runs like a dream! The oil pump is working fine, so that is why I believe it is my oil pickup sensor! A friend had the same problem, and after he changed the sensor, everything was back to normal!

KK

[GTP Dad]

It is possible that the sensor is bad. Replace it to see what happens. The SES light can indicate a problem with the emission system. Since it is an OBD 1 you can check the codes by jumpering the wires on the connector. If the light doesn't go out after changing the sensor then check the codes.

[krazyken2]

I had the comptuter scanned, and only two old history codes came up, but nothing new, or about the sensor! But now it looks like my oil pressure is really low! Any idea of what my oil pressure should read when hot???

Thanks,

Ken

[GTP Dad]

Usually the pressure will run between 20 and 25 pounds depending on the weight of the oil. If your pressure is low then I would first change the oil pressure sending unit since it may have gone bad. Or replace it with a mechanical guage. If it is still too low then you may want to check the level while running to make sure that the oil is properly draining back into the engine. This happens sometimes if there is sludge buildup in the drain back holes. Happens a lot in Chryslers. Other than that you may have to try a heavier weight oil.

Of course if you replace the sensor on the pan the problem may go away with the light.

[krazyken2]

Thanks GTP Dad. I'm begining to believe it may be a combo of 2 things! Even with the new sencor I still get a fluxuation of pressure! Sometimes at 21 psi, then drop to around 12 psi. This winter was the first time I have ran 5W 30! And the up and down pressure may be a result of the oil not getting back down fast enough! I'll try checking the oil level while running! At what level should the oil be on the dipstick if all is good!

Thanks again for the advice, you sure know your stuff!!

Ken

[GTP Dad]

If the engine is running as long as oil shows on the dipstick you should be ok. If it is not showing then something is stopping it from draining back correctly.

There are flush products available that you can put into the oil to flush the sludge out just don't move the car while you are using it then drain the oil immediately and put in fresh oil.

[tri-power]

We had a similar problem with the small block in our racecar. The oil was building up in the upper half of the engine and not returning to the pan.

[krazyken2]

I checked the oil while running and there is plenty of oil on the dipstick, and I watched the oil flow, by looking through the oil fill hole in the valve cover, and no sign of backup! I have heard it is not a good idea to use an engine flush, in an old engine??

Thanks

[maxwedge]

Originally Posted by krazyken2

I checked the oil while running and there is plenty of oil on the dipstick, and I watched the oil flow, by looking through the oil fill hole in the valve cover, and no sign of backup! I have heard it is not a good idea to use an engine flush, in an old engine??

Thanks

Agreed, heavy sludge build up can be loosensed, wind up in the pan and block the pick up screen, good bye engine!

[krazyken2]

Thanks Max!

I have come to the conclusion, that my oil pump is failing! I am going to book for a pressure test! Thanks all who have responded! This is a great forum, and I will recommend to everyone!

Cheers!

KK