Oil pressure drops as jeep warms up
01-15-2011, 02:49 AM
#46
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Year: 89
Model: Cherokee
Engine: Inline 6
throwing this out there,
when i bought the jeep like 2 months ago, i had a tranny problem changed the tranny didnt fix it, actually wound up being the TCU, but back to the point, when i had this problem i had to get it home some how, so i drove it as easy as i could but it wouldnt shift out of first after that is when i notices the rattle, and later figured out that the rattle has something to do with the oil pressure. the oil that was in it when i bought it was terriable, it was black and super thin. could this have ruind the bearings/pump because of ****ty oil?
when i bought the jeep like 2 months ago, i had a tranny problem changed the tranny didnt fix it, actually wound up being the TCU, but back to the point, when i had this problem i had to get it home some how, so i drove it as easy as i could but it wouldnt shift out of first after that is when i notices the rattle, and later figured out that the rattle has something to do with the oil pressure. the oil that was in it when i bought it was terriable, it was black and super thin. could this have ruind the bearings/pump because of ****ty oil?
01-15-2011, 03:12 AM
#47
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Year: 1990
Model: Cherokee
Engine: 4.0
Originally Posted by jesse jay
not burning oil out the exaust but i do lose a good amount of oil, and i can get the the main bearings jus by taking the oil pan off right?
im thinkin replace the main crank bearings and the rod bearings and i got a new pump to put in it already.
im thinkin replace the main crank bearings and the rod bearings and i got a new pump to put in it already.
01-15-2011, 08:09 AM
#49
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Year: 1988
Model: Cherokee
Engine: 4.o
You can tell , if they are bad enough they will look like brass. Mine were complete brass when i bought my jeep, the main bearings looked new. post some pics if you can, i would but i really dont know how its always a pain in the ***. Plastiguage is only a couple bucks. its sifferent sizes get the one thats up to .006. you chouldnt need to go over that or you really got alot of wear on bearings and crank. I beleive rod bearin allowance is up to.004 maybe .005 but thats from memory my book is in the shop. Mine still rattles at startup but i got clearances up to .007 thats bad but its a $300 trail jeep so im running it till failure. just dont get the caps mixed up do them one at a time and put them back thje same way they come off. BTW mine idles at about 0 PSI when hot, i only got 20 psi when cold so clearances do play a big issue, thats why everybody says run thicker oil, its a bandaid and thick oil dosent flow good when cold
Last edited by dbcox; 01-15-2011 at 08:23 AM.
03-20-2011, 10:18 AM
#50
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Year: 89 2 door
Model: Cherokee
Engine: 4.0
is there any more to this thread. having the exact same problem. 89 4.0l . driving over 45 minutes my oil pressure diminishes and i get all sorts of noise. its not the header its not the flywheel its strictly low end and valve train knock and tick . and i know knock. ive thrown two rods out the side of my 96 and it still ran and knocked up my drive way. there is a relief valve with a spring in the oil pump that creates the pressure. does anyone know if this valve fails etc? or does anyone know if this problem was fixed by changing their oil pump etc?
03-20-2011, 11:00 AM
#51
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Year: 92
Model: Cherokee
Engine: 4.0
I'm running rottella in my 89 and no ticking or anything in her . She has 190,000 miles on her only I've had to replace is oil sending unit and actually improved gas mileage too .
03-27-2011, 12:15 PM
#52
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Year: 1995
Model: Cherokee
Engine: 4.0 inline 6
I have an 89 Cherokee with a 4.0 inline 6, when its cold ill start it up and the oil pressure will be where its supposed to be at 45 but as it warms up the oil pressure drops till it hits like 5 to 10 or even lower the farther I drive, when I give it gas it goes up to maybe 20 but when I come to a stop it idles around 5. the engine will rattle too, only when the oil pressure is down that low when its cold it sounds like a champ, or even when its warm and the oil pressure is low, and I step on the gas it wont rattle. what could the problem be?
my 95 cherokee is rattling and has no oil pressure at an idle. i have oil pressure when i have my foot on the gas , but when i stop and or slow down i loose all of my oil pressure, but when the car is cold the gauge reads 40 and its fine just a little tick , but when it warms up it gets louder and i start to have the problem with my oil pressure, and i only have oil pressure at 1700 rpms or above , anything under i have none. And i just replaced the oil pump and stilll have the problem........Any suggestions????????????????????????????????
03-27-2011, 12:18 PM
#53
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Year: 1994
Model: Cherokee
Engine: 4.0
I have an 89 Cherokee with a 4.0 inline 6, when its cold ill start it up and the oil pressure will be where its supposed to be at 45 but as it warms up the oil pressure drops till it hits like 5 to 10 or even lower the farther I drive, when I give it gas it goes up to maybe 20 but when I come to a stop it idles around 5. the engine will rattle too, only when the oil pressure is down that low when its cold it sounds like a champ, or even when its warm and the oil pressure is low, and I step on the gas it wont rattle. what could the problem be?
03-27-2011, 05:55 PM
#54
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Year: 89 2 door
Model: Cherokee
Engine: 4.0
i may and most likely and hopefully figured this all out. and its farely simple. i will have a write up on it shortly as soon as the weather gets better here.
09-07-2011, 01:58 PM
#55
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Year: 2001
Model: Cherokee
Engine: 4.0
My oil pressure started dropping about 3 weeks ago, i've had the jeep for 2 years and it always ran at around 40psi (hot or cold always stayed within 35-45) recently it starts up fine and 10 minutes into driving it, it begins to drop slowly. It will basically drop to near 0 at idle speed if i've been driving for 40 minutes (the "check gauges" light comes on). But i don't believe i've heard any strange noise at all coming from the engine but i have had some coolant spill over after i park and been driving for a while (but temps stay normal, im so confused!)
09-28-2011, 09:26 AM
#56
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Year: 89
Model: Cherokee
Engine: Inline 6
The temp gauge might be bad. aswell as maybe your oil presure gauge. check them first and if your presure gauge is fine, what i did was put a new "high volume" oil pump in ran it with 10w 40 and a bottle of lucaus and it runs fine
09-28-2011, 01:06 PM
#57
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Year: 1996
Model: Cherokee
Engine: 4.0
Last summer, my brother's garage overfilled his Cherokee's crankcase with exactly double the oil required - 10 quarts! He drove it from DC to TN without a problem. When we were going to run go karts a cloud of white smoke began to form and we eventually discovered the overfill. but it ran all those miles beforehand with no sign of an issue. At my house, we drained the oil and refilled with 5 qts. for his trip home...
01-23-2012, 09:20 AM
#58
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Year: 1999
Model: Cherokee
Engine: 4.0 6cyl
started the jeep this morning and my oil gauge is low-10-20..It has always been around 40 at start up and when driving it runs 50-60..Do you think it is my oil pump?
I Just had the oil changed a couple of weeks ago- the oil stick is showing a little over full--they never over filled it before..I havent checked it since they changed it(until now) so I dont know if it was reading over full before this morning or not..would a bad oil pump make it read over full?
I Just had the oil changed a couple of weeks ago- the oil stick is showing a little over full--they never over filled it before..I havent checked it since they changed it(until now) so I dont know if it was reading over full before this morning or not..would a bad oil pump make it read over full?
Last edited by Lisa; 01-23-2012 at 09:26 AM.
01-23-2012, 01:01 PM
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Year: 1999
Model: Cherokee
Engine: 4.0 6cyl
started the jeep this morning and my oil gauge is low-10-20..It has always been around 40 at start up and when driving it runs 50-60..Do you think it is my oil pump?I Just had the oil changed a couple of weeks ago- the oil stick is showing a little over full--they never over filled it before..I havent checked it since they changed it(until now) so I dont know if it was reading over full before this morning or not..would a bad oil pump make it read over full?
I Just had the oil changed a couple of weeks ago- the oil stick is showing a little over full--they never over filled it before..I havent checked it since they changed it(until now) so I dont know if it was reading over full before this morning or not..would a bad oil pump make it read over full?it was the oil sending unit..Its fixed!!!!
