Is there such a thing as high oil pressure? Mechanical gauge in a 91 XJ and the pressure never drops below 45 psi even at idle. Kinda strange,but it is the first I6 I've worked on. Is this normal? Thanks

 

I would say no it is not normal. Mine is the same way except I get down to 40psi at idle on a hot engine. When driving I'm around 70-75psi. High oil pressure is not a good thing but it is much better than low pressure. Low pressure you tend to have severe mechanical damage and high oil pressure the worst you will really do is blow a seal.

 

Usually, this is caused by a bad oil pressure sending unit. Located directly above your oil filter.

You can verify your true oil pressure if you want with a mechanical oil pressure gauge, but to be honest, most people just swap in a new sending unit; they fail more frequently than the gauge.

I highly recommend purchasing the sending unit directly from Jeep for the best reliability/accuracy/mating with your factory gauge. Well worth the extra $20....

 

Sounds like there's something wrong with the gauge. I would check it with another mechanical diagnostic type gauge to verify.

 

In my case I have replaced the sending unit twice, once to verify the reading was correct and once cause I forgot it was there and snapped it clean off. With a total of 3 sensors I still have the same reading. X2 on verifying with a mechanical gauge especially since you can usually "rent" these for free.

 

x2 ....I have a 2000 Cherokee with a 4.0L, and while driving mine is at 50psi and a bit above 30psi when I am at a stop.

 

I put a mechanical gauge in a few weeks ago.Had just the idiot light. I'm pretty sure it's not the gauge as when I ran some Seafoam in it to try and get rid of some lifter knock it went down to 25 psi at idle. I'm assuming the oil was thinned by the Seafoam.After oil change with Rotella 15w-40 it was back up to 45psi at idle to maybe 55psi when driving. Still has the lifter knock that I havn't been able to figure out. Thanks