Chrysler Repair: 1999 sebring loss of oil pressure., oil pressure gauge, valve lifters

Question
QUESTION: I have a 99 seabring 2.5 V6. When I start it cold the oil pressure gauge show normal pressure. After it warms up it shows no pressure. I tried putting a heavier grade oil in the motor (same problem). I was told if it's the oil pump it's not worth the trouble. Your thoughts

Joe

ANSWER: Hi Joe,
I would begin by measuring the pressure using a calibrated gauge. The pressure sender unit unscrews and you can insert a gauge in it place. When the engine is warm the minimum pressure should be 6 psi at idle and 35-65 at 3,000 rpm.
If it passes that test, then get a new sender unit. If not, then replacing the pump is not so bad as to junk the car, unless you are already burning oil or the compression is way down.
Replacing the pump could be done at the same time you replace the water pump and the timing belt as they are all accessible at that point. So those are the factors to consider. The belt is supposed to be replaced at around 100,000 miles of use.
Roland

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QUESTION: Roland,
        guess I should have mentioned, when I first start the car it sounds good. After warming up and the pressure drops you can here the motor tapping like it's not getting oil. Could there be more problems than just the pump?

Answer
Hi Joe,
The valve noise confirms that the pressure is too low. What you are hearing are the valve lifters whose pressure level are insufficient to expand them enough to close the gap between their surface and the valve stem. You can probably skip the pressure test as this would be a good indication that you indeed have too low pressure. I would proceed to the belt change/water pump change/oil pump change procedure to solve this low pressure situation. If you intend to do this yourself let me know and I can copy and postal mail the pages on how to assess the oil pump. Or you may just want to buy a new one rather than to repair the old one.
If this has been the situation for a long time another possibility is that the bearing clearances are too large, which if the case would provoke the need for an engine rebuild. You didn't say how many miles the engine has on it and how long the pressure has been low in this manner. Unless you hear beaing noise (thumping) you could assume that is not the issue. But do a compression test on the accessible cylinders (2,4,6) to see how that is. I am not certain how much further diagnosis would be worth it to assure yourself that the pump alone will be adequate to provide more economical miles.
Roland