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Oil Pressure Problems with a high mileage Chrylser 5.7l Hemi

I own a 2005 Chrysler 300C with a 5.7l Hemi. Encountered OBDC P0521 and P0522 codes which the dealer addressed by replacing the oil pump and changing the oil to a 10w-40 non-synthetic (factory recommends 5w-20). The thought was that because the engine has over 163K miles and was not generating sufficient oil pressure at idle, the higher viscosity oil would increase oil pressure enough to keep the sensor from reporting low pressure. Now I have a new code, P0524, that may be related to the “wrong” viscosity?
The dealer claims to have addressed the low pressure issue with the new oil pump. The oil level is correct and is not contaminated (was just changed), and the oil pressure sensor was replaced to address the P0521/0522 codes along with the pump.
The dealer claims that my only recourse now is either to replace the engine or the PCM, neither of which I am anxious to pursue due to the age of the car.
Any thoughts? Am I being too optimistic to think that the new CEL and code is simply due to the incorrect oil viscosity being detected?

Potential causes of a P0524 code include:
Low oil pressure
Low oil level
Wrong oil viscosity
Contaminated oil (fuel, coolant, etc.)
Faulty oil pressure sensor
Signal shorted to ground in electrical circuit for sensor
Worn internal engine components (oil pump, worn bearings, etc.)

I have a 2009 Challenger with the 5.7L Hemi V8, around 124K miles. It burns about a quart of oil (5W-20 synthetic) every 6000 miles or so.

I think I’d take yours to an independent mechanic, myself. Get another opinion. Seems to me if you have a brand new oil pump, that ought to solve pretty much any low oil pressure issue.

I’d also switch back to 5W-20 oil, as that’s what the manual says to use. In fact, I was under the impression that the Hemi’s cylinder deactivation system is very sensitive to the oil viscosity. Which surprises me that the dealer put in 10W-40.

My suspicion would be a bad oil pressure sensor of some sort. It’s been my experience that when the dealer pulls out the “new engine” or “new PCM” cards… they really don’t want to deal with your issue. Hence the suggestion to get a 2nd opinion.

Good luck.

Replacing an oil pump is most often an exercise in futility. Look at it this way. If the theory is that an oil pump is worn out with the pump being the first thing that sees oil when the engine is started doesn’t it stand to reason that everything after the pump is also worn to the same degree or worse?
I’d bet there was nothing wrong with the old pump.

A guy I used to work with changed oil pumps on Fords all the time to cure(?) low oil pressure problems.
Not once did it ever work. It always led back to worn main and rod bearings.
The only way of knowing this is to drop the oil pan and remove some of the main and rod caps on the end of the engine fartherest away from the oil pump. Good luck.

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No, the oil pump could be a poor design that wore out before anything else did. But based on what I read here, that is very unlikely.

Or perhaps when the oil pump starts to wear out, pressure goes down, and everything else wears out faster. Cause and effect can be slippery sometimes.

I agree with @ok4450 . As he said the main and rod bearings are most likely worn and now the clearances are too big to build much oil pressure at idle.

I too don’t know anyone who had much better oil pressure after replacing the pump.

If you have ever run this engine low on oil, that can wipe out bearings in short order.


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I’ve only seen that on engines in which a high volume oil pump could be installed. The pumps on the end of the crankshaft and inline with the crankshaft don’t have space for a larger oil pump.

An old small Chevy, Ford or Buick V6 or V8, yes. And early (70’s to 80’s) Buick V6 engines really needed a high volume pump past about 100K miles. I had one like that. Gained 15 psi at idle and was the same at 4000 rpm due to the pressure relief.