Ironjeff1

I need help with a recurring oil pressure sending unit failure. I have a '99 Jeep Cherokee with 188k miles. It's in great shape and runs extremely well. I am the only owner and have changed oil/filter every 3,000 miles.

In November, the first oil pressure sending unit failed and was a Mopar replacement was installed. Problem solved. In February, the same thing happened and I figured the replacement sending unit was faulty. Mopar replaced it. It just failed again last week and I no longer think the unit is faulty, but rather something in my oil is clogging that small pin hole in the diaphragm in the sending unit.

I'm considering adding a pre-oil change additive to clean out any sludge that may have accumulated after so many miles and repeating this procedure after 1,000 miles. Following the second addition of additive, I will replace the sending unit to make sure it's not contaminated. If anyone has any suggestions to solve this recurring problem and my solution, your genius would be appreciated

RENIXBEAST

I would be looking more into the electrical aspect of the sensor. Maybe a short somewhere??

Ironjeff1

Thanks for the reply. I'll check for a short. The fact that the same problem reoccurs after about 90 days suggests to me it's more likely mechanical, but perhaps a short is minor enough that it's taking 90 days to effect the sending unit.

Purp

If it is just the sending unit. Hook up a mechanical gauge for your oil pressure. Make a mounting bracket and mount inside the vehicle.

lurk520

put a black piece of electrical tape over the gauge so you don't see it anymore. My oil pressure gauge acts like a tachometer, haven't tried replacing the sending unit yet.....

98 JeepJeep

really not much to "short out" on a oil pressure guage. if it had a short it would peg the guage or it wouldnt work at all....

If it is burning out than you might have got a bad batch of sensors...

Ironjeff1

I thought I'd post a follow up to this thread in case anyone encounters the same problem and is looking for a solution.

FOLLOW UP: While on a road trip this weekend, the alternator failed completely. First the charging gauge failed which triggered the Check Gauges warning light. As I kept driving the other gauges, the radio/CD player, the air conditioning, and turn signals shut down sequentially because I was running on battery power. I replaced the alternator and everything is fine.

My hunch is that the failing alternator created a series of intermittent electrical surges over a 90-day period that burned out the oil pressure sending units.

I'll add another update in a few months if the oil pressure sending unit fails again.

4x4utahcherokee

the wires to the sensor itself could be bad. I had a similar problem with my jeep and when replacing my sending unit I noticed my wires were brittle and had broke inside of the insulation itself. Needless to say I checked my pressure mechanically it checked out fine so I busted out the electrical tape and covered the light until I get a new wiring harness. Cherokee's run so hot all the time that it's not uncommon for the wiring to get baked to a nice brittle crisp.