help!

bought this one month ago. 2001 Dakota, 118K miles, appeared to be well cared for.
during the test drive the oil pressure gauge was fluttering, but was within the normal ranges.

Took it home to my mechanic. he replaced the oil pump with a high volume oil pump. no change he swapped out the pump to rule out that it may be faulty, still no change.
he then replaced the oil pan, screen, pickup tube. Still the same. He then replaced the sending unit. No change. Then replaced the oil pump drive shaft which appeared to be a bit worn. Nothing. Then he took off the sending unit and did a pressure test. Pressure was good.

However, now it is worse than before! Now every time I come to a complete stop or if the rpm goes down below 1k, the gauge drops to zero and the 'check gauges' alarm comes on. It is quiet on top, no sounds from the lifters, but what the heck?!

I called a Dodge dealer and their mechanic told me to just use an after-market/mechanical gauge, instead of the one that is in the instrument cluster.(why not just replace the gauge in the cluster??)

I've read on this forum that some people recommend replacing out the PCV valve and even the brake booster check valve, so I can try that, but has ANYONE had this happen and actually found out what the real issue is??

I bought this truck to start a company, and can't afford to have it failing on me out in the field.

Thanks in advance

 

btw, I also added SeaFoam to the tank to possibly clear out any sludge, no change.

However, it does tend to stall on me when I am sitting at a low rpm(like ins stop and go freeway traffic) and then as I begin to accelerate, it stalls. Same thing happens on occasion when I am backing into my driveway, as I am going from Drive to Reverse to back it in, I give it a little gas to back up and it stalls....

My mechanic did a complete fuel injection cleaning and changed the spark plugs....so I am totally confused at why this is happening, along with the oil pressure issue.

 

If the mechanical gauge says pressure is good, either the sending unit is bad, even though it is 'new', or, the gauge in the dash has issues.

Moving this to the correct section.

 

The issue with a high volume pump is that it will, quite literally, suck the pan dry. I will pull fluid in faster than it can drain back through the engine. You'll have to run an extra 1-1.5 quarts probably. Unless you can fit a high capacity pan (which is near impossible on a dakota/durango), HV pumps are never recommended.

As far as the pressure goes, What the dealer told you is correct. Permanently plumb a mechanical gauge in. You can't replace the gauge in the cluster, and the sending units have an awful level of consistency of quality control, because it's actually not a gauge at all. These engines are rated for 5 psi at idle plus 10 psi for every 1,000 RPM (or thereabouts). So at idle, you have no idea what actual pressure is, based on the below description from the Factory Service Manual:


Each time the cluster receives a message from the PCM indicating the engine oil pressure is below about 6.9 kPa (1 psi), the gauge needle is moved to the L (Low) graduation at the far left end of the gauge scale, the check gauges indicator is illuminated, and a single chime tone is generated.

Each time the cluster receives a message from the PCM indicating the engine oil pressure is between about 6.9 kPa (1 psi) and 137.9 kPa (20 psi), the cluster holds the gauge needle at a point about 11 degrees above the low end of normal increment on the gauge scale.

When the cluster receives messages from the PCM indicating the engine oil pressure is between about 137.9 kPa (20 psi) and 517.1 kPa (75 psi), the gauge needle is moved to the actual pressure position on the gauge scale.

Each time the cluster receives a message from the PCM indicating the engine oil pressure is between about 517.1 kPa (75 psi) and 755 kPa (109.5 psi), the cluster holds the gauge needle at a point about 7.4 degrees below the high end of normal increment on the gauge scale.

 

magnethead, hey you: Thanks for the info below. Will discuss this with my mechanic.

 

I have the same problem in my 2000 Dodge Dakota. Did you ever find out the cause?

 

Probably just the oil pressure sending unit. Common failure on those.

 

Jeez. Looking back at this old thread, that mechanic really took her for a ride. All those steps and not the cheapest and most likely fix first? Whew!