oil presure gauge problem

rkrichie

Have an 02 dakota 3.9, oil gauge was reading low to high so I did an oil change with a qt of lucas oil and a new sendung unit, now when I start it the oil pressure is high and when it warns up it returns to nomal. But when I hit the gas it moves to 3/4 line and when I slow down to a stop it slowly returns to 1/2 way nomal spot is this nomal or should I look deeper?

dustyk

Although your new sending unit sounds a little more reactive than what I'm use to, your description matches the expected way oil pressure would be in a normal operating engine. Normally you don't see much oil pressure fluctuation on Mopar engines with factory gauges and sending units. It is possible to be bypassing some oil pressure if you have an incorrect oil filter installed. This would produce a wider variation in pressure, but it often is accompanied by very low pressure at idle speed. But that doesn't seem to be a problem in your case.

At full operating temperature in summer, healthy, low mileage 3.9s typically idle at about 35-40 pounds oil pressure with fresh 5W30 motor oil and the correct oil filter (factory spec. minimum is 6 lbs.). Cold starts and colder weather usually raise the pressure at idle speed slightly. The oil pressure bypass in the engine is calibrated to open at 80 lbs. at 3000 RPM. At moderate highway speeds LA-series engines will typically produce 50-60 lbs. pressure.

High mileage (150,000 and up) and engines not well maintained will produce lower pressure numbers.

Best regards,
Dusty

russelljal

I have a 01 Dakota 4cyl. with about 135k i sent it to the mechanic with oil gauge problems and a rattle in the top of engine. he changed the oil pump and the rattle is gone how ever when i picked it up the gauges looked fine.. stayed in the middle of operating range until i get about a mile down the road and it starts to drop to just over 1/4 while driving when i stop it falls to the lower line of the operating range and goes up when i start driving. so when i get home about 5 miles i let the engine run while i am checking for any leaks for just a couple of minutes and when i go to turn the truck off i noticed that my oil pressure has completely dropped and my like is on.

63pro

I have a '91 Dakota with about 125K. I bought it used and oil was changed by dealer. I've noticed the oil pressure gauage rarely shows movement, no matter what the weather or how long its been driven. What is the best way to start handling this issue so guage works? I also have an oil leak but cannot determine its origin at this point, but it is not coming from newly changed valve gaskets. :confuse:

dakotablues

have a 2001 dakota, oil pressure goes from zero up to min. mark on guage. engine knocks real bad when pressure down to zero, is pump the problem? already drained oil half way and added kerosene and ran it 10 minutes to try to clean out sludge, then emptied oil and changed filter and added fresh oil, but still same problem. any help?