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Unread 05-09-2012, 03:23 PM   #1
ecricket
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1988 YJ Wrangler 
 
Join Date: May 2012
Location: amherstburg, ontario
Posts: 4
1988 jeep yj

hey guys i was wondering if you guys could help me out, i just replaced my rear main seal cause i was told it was bad but my oil pressure isnt going any higher then 10psi, and fluctuates when driving, i was wondering if my oil pump may be bad, like i have 7 quarts of oil in it, and it doesnt show on the dipstick at all.

any advice? id love to build this jeep up a lil when i have the time but first things first get it running smooth.

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Unread 05-09-2012, 04:31 PM   #2
roadyrob
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1987 YJ Wrangler 
 
Join Date: Apr 2007
Location: west palm beach fl
Posts: 1,784
you sure it isn't 6 gts. that normal capacity for the 4.2. you might have the wrong dip stick or tube. many years ago I bought a used ford truck and had the same thing happen, turned out to be the wrong dipstick. don't do what I did, I filled it up and the motor started leaking everywhere. check your oil pressure with a mechanical guage, you might have a bad one.
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Unread 05-09-2012, 05:03 PM   #3
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,954
If you have that much oil in it you need to stop driving it. You have enough oil in it to do damage. The oil pressure is not depenadant on the amount of oil as lond as you have enough to cover the pickup in the pan. Verify the sensor and guage are working by reading the resistance on the sensor only after you have the correct ammount of oil in the engine. Here is the readings you are looking for:
yjgaugespecs-1-.jpg  
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Unread 05-09-2012, 05:21 PM   #4
ecricket
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1988 YJ Wrangler 
 
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Location: amherstburg, ontario
Posts: 4
Thanks guys I did stop driving the jeep cause I knew something was wrong, Aka why I did the rear main seal thinking that was the issue.
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Unread 05-10-2012, 03:18 PM   #5
ecricket
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1988 YJ Wrangler 
 
Join Date: May 2012
Location: amherstburg, ontario
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I was just wondering what to do, I drained the oil put in 5 quartz of 5w-30 ran it for a bit, for some reason it started knocking so I went inside got my stethoscope to listen to it closer to see what it is, when I started looking my crank pulley is bouncing does that mean the crankshaft bearings are shot? And if so how much of a project is that going to be to fix this motor or should I get my hands on a small block ford or chevy motor?
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Unread 05-10-2012, 04:00 PM   #6
ClarkRCC
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1990 YJ Wrangler 
 
Join Date: Sep 2010
Location: Billings
Posts: 180
You need another quart of oil for starters, the 4.2 (258) is a six (6) quarts system; unless you have some kind of different oil pan
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Unread 05-10-2012, 04:22 PM   #7
Que89YJ
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1989 YJ Wrangler 
 
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Make sure the pulley is tight.
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Unread 05-10-2012, 05:48 PM   #8
medic-11
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1990 YJ Wrangler 
 
Join Date: Jun 2010
Location: Lakeland, FL
Posts: 258
Rear main seals dont make or hold oil pressure. Bearings hold oil pressure. I wont go as far to say oil pumps dont fail, but low pressure is rarely the cause of the pump. Unless your oil level was really low, it sounds like youve got a big problem.
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Unread 05-10-2012, 05:58 PM   #9
Tamatacan
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2013 JK Wrangler 
 
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Location: Seal Beach, Ca
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You need to pull the belt on the front pulley and see why it is loose. I have seen broken cranks and the engine still ran but the pressure was nil. This was out of a Race Suzuki M109. It ran great but make noise. This is what I found when I pulled it apart.
crank-1.jpg   crank-2.jpg   crank-3.jpg   crank-4.jpg  
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