Oil pressure issue

[Mac48]

My oil pressure drops when I start to drive.  It would seem that the pressure should raise if anything.  At idle it sets above the second large mark on the gauge and then when I accelerate even while setting it drops below the second large mark.  Any ideas would be helpful.  I don't even know where to start.

[Turbo Kane]

I would start by getting a cheapo mechanical oil pressure gauge and set it somewhere you can watch while driving to see exactly what’s going on. Your low pressure light will come on it it falls under 5psi so until that happens I’d say it’s safe to run the engine to diagnose. My cars have all had excellent oil pressure but a rule of thumb is atleast 10psi per 1000 rpm (30psi@3000rpm). Idle the lowest you’d want to see is 7psi. A healthy engine you’ll see about 15psi at idle. I would save the oil filter on there now and cut it open to look for debris between the flaps in the filter. Also drain the oil into a clear tub and using a bright flashlight look for debris usually aluminum clunks would be a sign of bearing failure. 

 

Best of luck.

Edited March 27, 2018 by Turbo Kane (see edit history)

[Hemi Dude]

By the looks of the RPM of your engine and the speed, I'm guessing you have a 2.2L engine. As I had written regarding a previous oil pressure question, by the Chrysler Factory shop manual, oil pressure at CURB IDLE  should be 4 psi minimum. At 3000 RPM 25-90 psi.

However yours drops as you accelerate. Other than installing a manual gauge to verify actuals oil pressure, you might try taking a look at the oil pressure sending unit mounted on the front side of the engine block almost directly under the thermostat housing and upper water hose leading to the radiator.

Look for a loose connection in the wiring harness to the sending unit. If it is even a little sloppy loose, it could be enough to loose connection when the engine torques up as you accelerate.

[Mac48]

Thanks both of you.  Sorry I didn't say.  Yes it is a 1989 2.2L. engine.  I have owned the car for 4 years and it has done this since I bought it.  I will look for a loose or or sloppy wire connection.  If not that I will check actual pressure with a gauge.

[Mac48]

PIcked up oil pressure tester from Harbor Freight.  At idle (900 rpm) had 54 psi.  At 3000 rpm had 65 psi.  Much relieved.  Replaced sending unit.  Now showing mid range on gauge with minimal increase upon acceleration.  Another happy customer.  Thanks for the help

[Hemi Dude]

Glad you got it repaired. Help is here when you need it. Always remember to include  " it is a 1989 2.2L. engine. "

[Reaper1]

The oil pressure senders are NOTORIOUS for doing this. For some reason they fail internally, leak, then stop working. My TC does the same thing. I know there's oil in it and when it happens and the lifters aren't noisy, so I know it still has oil pressure and the Check Engine light doesn't come on. I check the connector, sure enough it's got oil all in it. I never did change it...the whole engine is coming out! LOL (not because of a failure)

[Mac48]

Pretty sure that it was O.K. but for the $20 oil pressure tester from Harbor Freight it was comforting to see what the actual pressure was.