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1999 Jeep Grand Cherokee Oil Pressure Problems, Please Help!

jkmartin1964 jkmartin1964
New User | Posts: 1 | Joined: 09/08
Posted: 09/04/08
10:14 PM

1999 Jeep Grand Cherokee 4.0 242 cubic inches, oil pressure is good at a cold start and when engine warms it drops to the point that the check gauges comes on.  When you give it gas the oil gauge comes back up.  The engine has been completely taken out and completely rebuilt, replaced pistons, rod bearings, main bearings, oil pump, timing chain, cam bearings showed no wear, micked them and they were well within spec.  Reassembled engine, plastic gauged all oil clearances were within limits, but problems still persists.  In fact didn't change anything.  Checked oil pressure with mechanical gauge and it shows no different reading then the one on the dash.  Engine sounds fine, no rattles, ticks or bumps, let it idle for 45 minutes with oil pressure gauge at 0 and still no rattles, ticks or bumps.  Would like to know if anyone else is having this problem or if anyone has found a cure for this.  Thanks in advance!  

diy_dad diy_dad
New User | Posts: 6 | Joined: 08/08
Posted: 09/05/08
02:38 PM

Try a heavy weight oil 20w50w My Trans Am shows low oil pressure when hot also and I had the engine rebuilt with a new oil pump but I should have bought a high pressure oil pump not a high volume pump. So I went to the thicker oil and at least the oil pressure light dosn't come on.  

stumpted stumpted
New User | Posts: 1 | Joined: 09/08
Posted: 09/10/08
04:31 PM

I am having the EXACT same problem.  No heavy oil does not fix it.  After reading your post I can only assume that a portion of tubing has become blocked somewhere in the block.  I just began looking at oil pumps and other parts assuming it was the pump.  Then decided to google for information and found this.  I have not talked to anyone locally who has experienced the problem.  i have noticed that after an oil change with fresh new oil the problem usually goes away for a little while.  however this period of time varies greatly.  If you have discovered anything else about this please let me know.


johnphufnagel johnphufnagel
New User | Posts: 2 | Joined: 10/08
Posted: 10/05/08
06:19 PM

Confused I am haveing the same problem I havent changed the oil in 4 monthts I thought that was the problem so I bought royal purple 15w40 it worked fine for about an hour then I came to a hard stop and it droped to zero.
If anyone knows what the problem is please let me know
thanks.. John  

lmt1 lmt1
New User | Posts: 1 | Joined: 10/08
Posted: 10/07/08
02:45 PM

My  problen with my '99 Jeep Laredo is when i start it the pressure stays at zero until it warms up even though the oil is fine.... any suggestions???  The warning light alarm is driving me crazy!!  

shipfaced shipfaced
New User | Posts: 1 | Joined: 10/08
Posted: 10/20/08
06:47 PM

10-20-08 I have a 1999 Jeep Grand Cherokee just turning 199000 miles and the oil pressure dash gauge just did the same thing. There doesn't seem any problem with the oil getting through the engine.  

hotrod1969 hotrod1969
New User | Posts: 2 | Joined: 10/08
Posted: 10/21/08
10:32 PM

My point of view comes from a machinist and also working in the automotive engine rebuilding line of work.  I have seen on jeep 6 cyl engines the connecting rods become out of round and at the parting line (the macined surfaces) and are egg shaped. feeler gauges wont show this condition nor will plastigauge each of these methods only show the overall average not the exact oil clearances at all positions of the connecting rod.  We found that macining the connecting rods round and puting the oil clearences on the minimum specs. it had great oil pressure.  

2001jeep6 2001jeep6
New User | Posts: 4 | Joined: 11/08
Posted: 11/13/08
05:22 PM

i just started having the same problems with my 2001 jeep grand cherokee at idle the pressure is 0 driving it's normal any answers please help  

waynep712 waynep712
Enthusiast | Posts: 651 | Joined: 10/08
Posted: 11/13/08
11:21 PM

2001 jeep 6... try changing the oil pressure sending unit below the distributer...   use some spray cleaner to clean the area around the sender first..   then with the coil wire unplugged... crank the motor over for a few seconds with the sending unit out..  this will clear the oil galley leading to the sending unit...

you might also check the grounds from the battery negative to the engine and the body....

oh... and it takes a special deep oil pressure switch socket to change the sending unit..   not pliers...  pliers can damage the crimp and shorten its useful life . (most chain parts stores have that tool for rent)  

Jbean678 Jbean678
New User | Posts: 2 | Joined: 11/08
Posted: 11/20/08
07:56 AM

I am having the same problem with my 2000 jeep grand cherokee laredo with the oil pressure gauge.  Just got my oil changed a few weeks ago, have only gone abot 6,000 miles, and believe it or not, there's less than 60,000 miles on the car.  But the warning light beeps when it comes up and it's driving me crazy, car drives fine.  Gauge goes to zero if I idle or decelerate, and the light beeps and comes on, but I don't feel anything different in the car.  When I accelerate or maintain speed the guage comes back up and maintains, the light goes off, and everything is fine until I decelerate or idle.  Did anyone with this same issue ever figure out what the problem is?  Is the car safe to drive?  

Jbean678 Jbean678
New User | Posts: 2 | Joined: 11/08
Posted: 11/21/08
03:19 PM

Me again, I got sick of the infernal beeping after one night.  Went to the dealership I bought the car from.  Cost $56 for the diagnostic test to be done and I found out the problem is the "Oil pressure sensor switch".  That will cost $142 for parts and labor.  But there is nothing wrong with the car itself which I'm thrilled about!  

jmjones26 jmjones26
New User | Posts: 1 | Joined: 11/08
Posted: 11/24/08
09:25 PM

you need to put a factory oil filter on it  

j_rossdale j_rossdale
User | Posts: 139 | Joined: 11/08
Posted: 11/25/08
01:30 AM

A quick check is to make sure the o-ring thingy that seals the oil pickup tube where the pickup plugs in isn't damaged.  
John R. seeking for the best maintenance help on Toyota Corolla cars..

larksailing larksailing
New User | Posts: 1 | Joined: 12/08
Posted: 12/30/08
08:10 AM

I am having the same problem and my 2000 jeep grand cherokee laredo is in the shop as I write.  I will let you know what comes of it.  

2001jeep6 2001jeep6
New User | Posts: 4 | Joined: 11/08
Posted: 01/05/09
08:15 PM

thank you all for your input the problem was the oil pressure switch now i lost my over drive any advice on what the problem could be  

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