91 Eliminator... High Oil Pressure?

[GirsMJ86]

OK, so it has been awhile since I have had to post anything. But I have been messing around with the 91 a bit more as of late, and I noticed the oil pressure seemed higher then I remember. So if someone could tell me what the oil pressure for a 91 High-Output would be it would help a lot. My gauge is reading about 55, idle at about 600. Seems to me the gauge use to read about 40 at idle. Only number I could find in my factory service manual is 13... so yea.

 

It is going to have to be taken in to have some metal hoses on the radiator replaced and the E-Brake replaced, along with a few other minor things. I am just trying to make a list of what else needs repaired/restored once I get another car so I can actually be without the truck and not carless for work.

 

On the good side of news, I got my custom plates ordered for it. 91 ELM8R.

 

Thanks guys,

Alex

[HOrnbrod]

OK, so it has been awhile since I have had to post anything. But I have been messing around with the 91 a bit more as of late, and I noticed the oil pressure seemed higher then I remember. So if someone could tell me what the oil pressure for a 91 High-Output would be it would help a lot. My gauge is reading about 55, idle at about 600. Seems to me the gauge use to read about 40 at idle. Only number I could find in my factory service manual is 13... so yea.

 

It is going to have to be taken in to have some metal hoses on the radiator replaced and the E-Brake replaced, along with a few other minor things. I am just trying to make a list of what else needs repaired/restored once I get another car so I can actually be without the truck and not carless for work.

 

On the good side of news, I got my custom plates ordered for it. 91 ELM8R.

 

Thanks guys,

Alex

 

Welcome back Alex. My 91 reads about 50 PSI at idle, and my idle is about 800 RPM. Also I have the Hesco high output oil pump if that makes a difference.

[JeepcoMJ]

he's running a jasper so it should be higher anyways.

[HOrnbrod]

he's running a jasper so it should be higher anyways.

 

Okay, I'll bite - why should a Jasper engine have higher oil pressure?

[GirsMJ86]

he's running a jasper so it should be higher anyways.

 

Okay, I'll bite - why should a Jasper engine have higher oil pressure?

 

Well if he is jokin idk what the joke is. I do know that it has only about 55k miles on the engine, full synth valveoline max life 10w-30, and that jasper tends to up the engines a bit since they stick their NASCAR tech into the motors they redo and build.

 

I also have a K&N cold-air cone tube intake. upgraded plugs and wire, and roto cap. Once it goes in it will be gettin a complete overhaul. this way every tube, wire, pipe, plug, ect... is new. It will also get an upgraded oil pump, alt, and maybe a turbo... or was it a supercharger, i don't remember anymore. lol. plus the all steel cowl hood. but none of that addresses the issue here. I'm just running my jeep mouth again.

 

So, that is why Jaspers are higher. If I'm not right then fill me in too Pat, along with any info you may have on the parts swap. lol. See ya all later.

 

Alex

[CWLONGSHOT]

Here is a video clip took from mine just tonight after the new fuel pump was installed. I happened to also be having a problem with believing my Bat gauge....its reading 9 volts when my meter reads 15volts... i have a HI AMP alt and new oversized lines so I don't believe the gauge...

 

That's my point...done believe it!! We have old trucks. I am going to put in a good aftermarket amp meeter and see what that says.

 

Any how, near the end of this clip, I give you a shot of my dash at idle. mine is a 4.0 W/ 83,000mi original.

 

CW

 

[jeepdoggydogB]

I also have a 91. but my warm oil pressure is 18 at idle, 40+ at higher RPM's. When cold I get the same reading you get at idle, at higher RPMs I get 60. I have 140,000+ miles and use 10/30 chevron oil with a chevron oil filter(probably a fram). :eek:

[HOrnbrod]

Yeah, I agree with CW. The XJ/MJ cluster gauges were never high precision gauges to begin with, and after almost 20 years, I expect the tolerance is probably +/- as high as 50%. Been running the same cluster through two engines, and the readings have been pretty consistent throughout. When something doesn't look right, I double check with my DVM. My voltmeter is AFU too, reads less than 12VDC when anything is on, like the radio. That's with a HO alt, oversize cables, etc. So I don't worry about it anymore.

[JeepcoMJ]

Jasper motors are supposed to have higher output oil pumps in them, as they are supposed to have a higher performance and less tolerance for low oil pressure. they also should demand a slightly higher fuel pressure but will work just fine in a stock vehicle.

 

 

on the note of problems with gauges, I have 7 or 8 gauge clusters here. 2 full ones for 2.8/2.5's (about half-complete now), 2 for 4.0's (one is perfect, one without fuel gauge), and a couple non-tach but full other gauges clusters, plus dummy clusters.

 

anyways, the 3800 was showing less than 9 volts with everything turned on, and I just had the alternator built to higher specs (145 amp) so it should supply me with more than enough power to run dual 10" subs and a 1200 watt amplifier, much less 4 fogs and just one 10 inch and a 600 watt.

 

so I played with the clusters and found one voltmeter that read at 16 when idle and nothing on, and 15 with everything turned on. that's right on the money with my diagnostic rack's voltmeter so I know it's correct.

 

put it in and now I'm happy.

[CWLONGSHOT]

So your saying out of the 7-8 you have only ONE was correct?? Kinda proves our point now don't it? :brows:

 

Bottom line, don't trust the factory gauges 100% unless you have checked against known accurate electronics.

 

CW

[JeepcoMJ]

So your saying out of the 7-8 you have only ONE was correct?? Kinda proves our point now don't it? :brows:

 

Bottom line, don't trust the factory gauges 100% unless you have checked against known accurate electronics.

 

CW

 

no, out of 3 I have one that reads satisfactory.

 

all the others were for engine options that won't work with the 3800 (4.0 or dummy lights) so I opted for the ones that WOULD work.

[MrShoeBoy]

Get a mechanical oil pressure gauge and hook it up in the same spot as the factory sending unit was at. Then run the engine and check the mechanical gauge to get real time accurate pressure numbers. You don't want the pressure over 60psi otherwise the distributor gear and cam gear will wear out rather quickly. Get a real gauge, check, then decide on what to do. The cheap option is to change the weight of oil, other option is to drop the pan and replace the pump. I have had very good luck the products that Hesco sells, including the oil pump which has been checked and flows at the proper volume and pressure. It is expensive but having built a lot of Jeep motors and some of which didnt last, I learned you get what you pay for in regards to motor building.

 

AARON