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4.0 Oil Pressure

Old 01-10-2009, 07:36 PM
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Default 4.0 Oil Pressure

So I was having issues with my oil pressure... While driving my oil pressure would be fine. When I stopped at a stoplight or got off the highway the pressure would drop causing the check gauge light to come on. Take back off and the pressure would increase again..


So the answer was (drumroll) A new oil pump...

After a couple of hours and about 100$ the XJ is back an operating at normal oil pressure. I was at the store getting my new oil pump and as I was describing my symptoms to a guy behind the counter a customer down the way says, "Hey you own a Jeep". I replied with "why Yes I do", he said he could tell by the description of the problem what type of vehicle I was talking about. He went on to explain that he personally has fixed somewhere to the tune of 60 of these exact issues him self this past year. He then proceeded to call a guy that he just instructed on how to fix the issue and the steps need to replace the oil pump. The person while on speaker was asked "Hey Tommy, what did I just tell you how to fix on your jeep? Tommy replies, How to change my oil pump. The guys says and why was that, so Tommy describes his symptoms, matched mine to a T. After hanging up the phone with Tommy the guy tells me he goes to the Auctions and finds Jeeps with 0 oil pressure and picks them up for almost nothing cause the people selling them thing the engines are going bad. When all it needs is a new pump.

SO a real basic Run down…

Bought the new pump

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And a new Gasket

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Removed the Oil Pan

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Removed the Starter for ease of Pan removal

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Removed the PUMP

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Took Filter Screen and Pick up Tube for new pump…

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Prime the pump by adding oil directly to the pump and spinning the pump actuator.

Install pump. Line up Gasket. Replace cover. Add oil.


Assemble in Reverse
Old 01-10-2009, 08:46 PM
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Nice job, ok write up lil more detail in the future.

In pic 3 you have a bar mounted under your pan. What is that? Is that some sort of extra brace.

I will be looking to do this same job later this spring. What method did you use to get your pan gasket to seat well. That was the hardest part when I did my Rear main on the other jeep.
Old 01-11-2009, 08:17 AM
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The Bar under oil pan is my steerung box brace.. it is not standard, i bought it seperate from my lift.. not everyone will have one...

And as far as the GASKET.. in my mind LUCK.. I set it up in the groove of the pan and had a buddy help set the pan... The biggest PITA part was back where it buts up against the Tranny kinda tight fit.. But mine seems ok so, we will keep our fingers crossed.. Also what I learded is that it recommended that 6 qts of oil are used for the 4.0... It is off the quadratec web site..
Old 01-11-2009, 09:43 AM
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Originally Posted by pbo2274
Also what I learded is that it recommended that 6 qts of oil are used for the 4.0... It is off the quadratec web site..
What were you putting in?

Nice little write up....when the day comes to finally tackle my rear main, i'm thinking about going ahead and putting a new pump on while im in there. How much did the pump run you?
Old 01-11-2009, 10:56 AM
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The oil pump was 82$..

I had always thought that the older engines used 5 qts... or maybe a smidge over...
Old 01-11-2009, 05:46 PM
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OK I thought it was just me, but I put in 5 quarts in my jeep and its perfect.
Old 01-11-2009, 06:30 PM
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Nice write up
Old 01-11-2009, 06:33 PM
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haha i can see yur crank
Old 01-12-2009, 06:24 AM
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Originally Posted by 76ANTHONY
haha i can see yur crank

I am a bit self concious about my crank could you stop staring please, its just like everyone elses... lol
Old 01-12-2009, 06:33 AM
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Although this has write up potential I don't think it yet qualifies to placed in the write up section. The detail is just non existent.

For ex... You wrote remove oil pump... Ok HOW!!! How many bolts what size wrench and blah blah blah.
Old 01-12-2009, 06:57 AM
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I run 6+ Qts... I use a 1QT filter, but I add a Lucas in place of the Dino-Juice...
Old 01-12-2009, 12:52 PM
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Originally Posted by XJ Stryker
Although this has write up potential I don't think it yet qualifies to placed in the write up section. The detail is just non existent.

For ex... You wrote remove oil pump... Ok HOW!!! How many bolts what size wrench and blah blah blah.

Aint hurtin my feelings none.. I dont think basic mechanic skills should be explained.. Heck I am nothing but a backyard mechanic.. I learn as I go... It can be moved to the off topic for all I care...

I can tell ya that I havent found any other post about it at all.. SO when someone wants to get the time on their hand to go write a better one, please be my guest....
Old 01-12-2009, 02:15 PM
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Just went thru the whole process myself the worse part is getting the pan off other then that it's pretty simple.....
Old 01-12-2009, 04:36 PM
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Originally Posted by Teal96XJ
Just went thru the whole process myself the worse part is getting the pan off other then that it's pretty simple.....

Yea.. After taking the starter down it was a ton easier.. PLus I did not have to contend with the axle because of the height of my lift just the steering box brace...
Old 12-14-2010, 08:39 PM
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Ok I know it`s been a year but could you tell me if you had any issues removing the pickup tube ? If not heard of any tricks for those tuff ones...

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