oil pressure gague jumping around

[STERLING STINGER]

ive noticed that my 88, (with the new motor) .....oil pressure guage is fluctuating

when it is american idoling, the gague reads close to 0.....like .5

when the motor is at a high rpm, it reads around 30

someone told me the rule of thumb was every 1K rpms, the gague should be @ 10

ie: 3000 rpms, 30 on the gague.

is this true?

 

btw, i check the oil all the time and its good, it hasent leaked even a drip since the swap :banana:

 

should this gague be jumping around like that?

my 92s dosent move that much, a little but not like that

 

thanks in advance :bowdown:

[Blue XJ]

I would check the wire going to the oil pressure sender, if thats good, it wouldn't hurt to replace the sender, they are pretty cheap.

[STERLING STINGER]

so its NOT normal for the gague to be doing that!!!

see, i knew it......my jeep skillz are growing slowly :chillin: .....thanks!

[Geonovast]

Get ahold of a mechanical oil pressure gauge you can hook up to where the sender goes to verify actual oil pressure.

 

If that reads good, replace the sender and/or gauge.

 

If the mechanical gauge agrees with the dash gauge.. you have bigger problems, and most likely need new rod and main bearings.

[STERLING STINGER]

Get ahold of a mechanical oil pressure gauge you can hook up to where the sender goes to verify actual oil pressure.

 

If that reads good, replace the sender and/or gauge.

 

If the mechanical gauge agrees with the dash gauge.. you have bigger problems, and most likely need new rod and main bearings.

thanks for raining on my parade.. :thumbsup: .....i figured there was more to it...there always is :wall:

thanks though :D

[Geonovast]

I know it sucks... but nipping a bearing problem in the butt now is better than having it seize on you 50 miles away on the interstate, and you ending up needing to change the motor again.

[STERLING STINGER]

ya........id better get on it

make some calls to get another gague to check it

 

thanks man :cheers:

[STERLING STINGER]

stupid question for you guys.....gold to me

 

where is the sender located? :shake:

[Geonovast]

Passenger side, right behind the distributor. It has a one wire plug going to it, and it's about the size of a shotglass.

 

[STERLING STINGER]

:bowdown: :cheers:

[Geonovast]

And in the future, this definitely qualifies as a tech question, so you can put stuff like this in the MJ Tech forum. :thumbsup:

[STERLING STINGER]

man i always get yelled at....STOP TELLING ME HOW TO RUN MY LIFE!!!!!!!!

:nuts:

 

JUST MESSIN WITH YA....OK ILL POST IT THERE NEXT TIME WHEN I ASK THE SAME QUESTION...LOL

[Eagle]

Your gauge is not "jumping around." The oil pressure goes up when the engine RPMs increase, and goes down when the RPMs decrease. The gauge should show that. "Jumping around" would be if you held the RPMs at a constant speed and the needle was jumping all over the place.

 

The factory spec on oil pressure, at normal operating temperature, is a minimum of 13 psi at idle (650 RPM), and between 37 and 75 psi above 1600 RPM. The rule of thumb about "10 psi per 1000 RPM" is exactly that -- a rule of thumb. I've never EVER seen it be that way in a real vehicle. In practice, most of the XJs and MJs I have owned idle at 25 to 30 psi, and run between 50 and 55 psi at highway speeds (55 to 70 MPH). Once warmed up, I've never seen any of them run higher than 55 psi at 70 MPH. My '88 XJ dropped to just under 40 psi at highway speeds around the time I hit 175,000 miles on conventional 10W40 oil, so I switched over to 5W50 full synthetic and it went back up to around 45 psi. I'm now at 287,000+ miles and the oil pressure still runs about 45 psi on the road, so I'll live with that.

 

But, back to your post -- the oil pressure SHOULD be lower at idle than it should at 2000 RPM. If it isn't, either the gauge is bad, the sender is bad, or you have bearing or oil pump problems.

[STERLING STINGER]

Your gauge is not "jumping around." The oil pressure goes up when the engine RPMs increase, and goes down when the RPMs decrease. The gauge should show that. "Jumping around" would be if you held the RPMs at a constant speed and the needle was jumping all over the place.

 

The factory spec on oil pressure, at normal operating temperature, is a minimum of 13 psi at idle (650 RPM), and between 37 and 75 psi above 1600 RPM. The rule of thumb about "10 psi per 1000 RPM" is exactly that -- a rule of thumb. I've never EVER seen it be that way in a real vehicle. In practice, most of the XJs and MJs I have owned idle at 25 to 30 psi, and run between 50 and 55 psi at highway speeds (55 to 70 MPH). Once warmed up, I've never seen any of them run higher than 55 psi at 70 MPH. My '88 XJ dropped to just under 40 psi at highway speeds around the time I hit 175,000 miles on conventional 10W40 oil, so I switched over to 5W50 full synthetic and it went back up to around 45 psi. I'm now at 287,000+ miles and the oil pressure still runs about 45 psi on the road, so I'll live with that.

 

But, back to your post -- the oil pressure SHOULD be lower at idle than it should at 2000 RPM. If it isn't, either the gauge is bad, the sender is bad, or you have bearing or oil pump problems.

thanks eagle you rule