03 GC lost oil pressure
#1
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Year: 97
Model: Cherokee
Engine: 4.0
03 GC lost oil pressure
my mother in law has an 03 GC which lost oil pressure, funny thing is when ya turn the key on before ya start its reading 40lbs of pressure,, but i pulled the valve cover off and started it and the rockers are clacking away with no oil pumping up, i do see some sludge , now im wondering do u guys think the oil pump screen is clogged?,or the oil pump just crapped out??? and how much of a PIA is it to get the oil pan down,, 4.0. She bought it used 5 yrs ago with only 65,000 miles now has 102,000,, she always had the oil change at 3000 miles..and where is the oil pressure sender on this motor???
THX
THX
#2
Old fart with a wrench
Yes, it's on the passenger's side of the block near the rear corner. It kind of hides behind a wire bundle.
Take it out and start the motor. If you've got any flow at all, the pump is fine. My advise is to change it anyway, I doubt the intake screen is plugged, but it could be a internally collapsed filter. Did that make any sense at all? Two thoughts crossing in the fog. Anyway, the pan can be dropped without much trouble, I've been told. I haven't done it myself yet (thank God!). You may have to remove the front driveshaft and starter for working room. The only other thing it could be is a spun bearing--worst case scenario.
Take it out and start the motor. If you've got any flow at all, the pump is fine. My advise is to change it anyway, I doubt the intake screen is plugged, but it could be a internally collapsed filter. Did that make any sense at all? Two thoughts crossing in the fog. Anyway, the pan can be dropped without much trouble, I've been told. I haven't done it myself yet (thank God!). You may have to remove the front driveshaft and starter for working room. The only other thing it could be is a spun bearing--worst case scenario.
Last edited by dave1123; 01-25-2014 at 01:44 PM.
#3
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Year: 97
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Yes, it's on the passenger's side of the block near the rear corner. It kind of hides behind a wire bundle.
Take it out and start the motor. If you've got any flow at all, the pump is fine. My advise is to change it anyway, I doubt the intake screen is plugged, but it could be a internally collapsed filter. Did that make any sense at all? Two thoughts crossing in the fog. Anyway, the pan can be dropped without much trouble, I've been told. I haven't done it myself yet (thank God!). You may have to remove the front driveshaft and starter for working room. The only other thing it could be is a spun bearing--worst case scenario.
Take it out and start the motor. If you've got any flow at all, the pump is fine. My advise is to change it anyway, I doubt the intake screen is plugged, but it could be a internally collapsed filter. Did that make any sense at all? Two thoughts crossing in the fog. Anyway, the pan can be dropped without much trouble, I've been told. I haven't done it myself yet (thank God!). You may have to remove the front driveshaft and starter for working room. The only other thing it could be is a spun bearing--worst case scenario.
#4
Old fart with a wrench
One other thing. Don't buy anything other than a Mopar sensor. I bought a NAPA Premium sensor and it only reads 20 psi all the time. It actually goes up to 35 when the OAT is -15*F. It has a printed circuit and a crystal in it that is critical for proper function. It was made in Mexico, not China. Mopar's is a bit pricey, but the NAPA one was $49.95.
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One other thing. Don't buy anything other than a Mopar sensor. I bought a NAPA Premium sensor and it only reads 20 psi all the time. It actually goes up to 35 when the OAT is -15*F. It has a printed circuit and a crystal in it that is critical for proper function. It was made in Mexico, not China. Mopar's is a bit pricey, but the NAPA one was $49.95.
#6
Old fart with a wrench
You never said weither it was a 4.0 or a V8. I gave you info on the 4.0 I6. I hope it is. Never mind, I reread your post.
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Old fart with a wrench
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Year: 2004
Model: Grand Cherokee
Engine: 2000 4.0
Dave,at idle speed it CAN take that long on a cold 4.0 and that is normal,especially if it has been sitting for a awhile. The cold thick oil takes awhile to get through the small orifices of the lifters and pushrods. This is normal and won't harm a thing b/c there is plenty of residual oil in the rockers to provide adequate lubrication.
#11
Old fart with a wrench
I was more concerned about the bearings. I use 10W30 full synthetic in my WJ and after sitting for 3 days at below 0 temps, it fired right up and I had oil pressure in 3 seconds. It did crank a little slow however. That's a 4.0 at 150K.
SAE says that 90% of bearing wear occurs before oil pressure comes up. I use the 10W because of the mileage although jeep calls for 5W.
SAE says that 90% of bearing wear occurs before oil pressure comes up. I use the 10W because of the mileage although jeep calls for 5W.
Last edited by dave1123; 01-27-2014 at 07:32 AM.
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Year: 2004
Model: Grand Cherokee
Engine: 2000 4.0
I was more concerned about the bearings. I use 10W30 full synthetic in my WJ and after sitting for 3 days at below 0 temps, it fired right up and I had oil pressure in 3 seconds. It did crank a little slow however. That's a 4.0 at 150K.
SAE says that 90% of bearing wear occurs before oil pressure comes up. I use the 10W because of the mileage although jeep calls for 5W.
SAE says that 90% of bearing wear occurs before oil pressure comes up. I use the 10W because of the mileage although jeep calls for 5W.
That is true about wear at startup but it is not the bearings b/c they have enough residual oil to keep them lubed until pressure builds. Most startup wear is on the valve train components b/c it takes this long for oil to get to the top of the head.
#13
Old fart with a wrench
That may be true, but the lifters are supplied directly off the main oil gallery that supplies the bearings, so they get oil right away. The rockers don't create noise, but lifters do. I would relate valve noise directly to lack of oil pressure. Or bad lifters. Again, I haven't had a 4.0 apart, but if the pushrods are hollow like GM's are, the lifters pump oil to the rockers so oil may be slow coming up.
The oil filter should have a check valve in it to prevent drainback, so the pump should hold a prime. This was a problem with GM V8's that was cured by changing the filter specs.
Again, this is just my opinion, but it has some basis of fact.
The oil filter should have a check valve in it to prevent drainback, so the pump should hold a prime. This was a problem with GM V8's that was cured by changing the filter specs.
Again, this is just my opinion, but it has some basis of fact.
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Year: 97
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well it turned out there was sludge in the pan clogging the oil pick up,, also the oil pressure switch was bad saying it had oil pressure before the engine was even running,, so that never triggered the oil light to come,, once i drained what little oil was in there,, only 1 qt,, put a new oil pump and pic up in and clean all the sludge i could see, this thing runs as if it never had an issue,,has 60lbs of pressure cruizing and 40lbs at idle, , thx for the info guys
#15
Old fart with a wrench
Another testimont to the heartyness of the 4.0! Takes a licking, keeps on ticking!