740 GLE 1988 Oil Pressure Light stays on after replacing H/G

crtjester8 · Post by **crtjester8** » 12 Jun 2009, 09:50

Yesterday I replaced the Head Gasket, Water Pump, and Timing Belt. Today, the Oil Pressure Light comes on, stays on, flickers. Because I have water in my oil I figured I should change the oil and filter. But as I went to go this, I removed the oil cap and it doesn't look like there is an adequate amount of oil at the top of the engine. I shut it off immediately. I don't hear any tapping or knocking noises. I guess my question is would water in my oil cause the oil pump to stop working? It worked just fine prior to replacing head gasket etc ( the light has never come on until now). Could all of that creamy sludge that is throughout cause this low pressure? Also, with key on ( light was on) I unplugged the oil pressure sending unit and the light went out, plugged it back in light comes on, so I don't think the sending unit is bad, not sure though. Thanks for any help you can give.

Post by **vegasjetskier** » 12 Jun 2009, 14:58

The water in the oil won't stop the pump from working, but your strainer (intake tube) might be plugged up with the oil/water emulsion. You might want to drop the oil pan and check it out. Anyway, you don't want to run your engine for long with the oil pressure light on.

crtjester8 · Post by **crtjester8** » 14 Jun 2009, 10:31

Thank you for the information/advice. Just when you think things are at their worse, well you know the rest. The friend/mechanic that is working on my car was able to determine that the oil pump drive gear is not working before he decided to get drunk while working on my car... nice huh? Anyway after insisting he wait until Monday to drop the oil pan, I was wondering, is the drive gear pretty much the main part of the oil pump? Should I just get a new oil pump? He said something about a sheer pin.. what is that? Thanks again.

Post by **billofdurham** » 14 Jun 2009, 12:29

A shear pin is the mechanical equivalent of an electric fuse. It is designed to break in the case of a mechanical overload, preventing other, more-expensive parts from being damaged.

I have never heard of a shear pin in an oil pump as it would be counter productive.

Check the strainer as suggested by vegasjetskier. If that is clear then it would seem that a new oil pump will be needed.

Bill.