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Unread 05-09-2009, 06:32 PM   #1
carlsjeep
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Losing Oil Pressure

I have a 2000 4.0 Wrangler and lose oil pressue at idle after the engine heats up. I have following symptoms but can not find a solution

1) Losing 4 qts of coolant every 800 miles. There is no sign of where it is going. Not on the ground, under the hood, through the exhaust or in the oil.

2) It appears that the oil is getting very hot. The grip on the oil filter is turning to dust at oil change time and the oil gets dark very fast. There is a hint of a burnt smell in the oil also.

3) Engine temperature is ok, never overheats.

4) Oil pressure starts at 40 psi when engine is cold and drops to zero at idle when engine is hot. I have removed the oil cap and can see a good amount of oil circulating over the lifters.

5) Oil pressure sending unit has been replaced with OE part.

My only theory is that the coolant is not circulating through the entire engine, only a portion of the motor and this is causing the oil to over heat and get very thin.

I know that I have seen this issue posted several times, but have not seen a resolution other then replace the motor.

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Unread 05-09-2009, 07:00 PM   #2
GOLENJEEPTJ
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If your losing that amount of oil that fast and it's not leaking your burning it!That's all there is to it!
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Unread 05-09-2009, 07:03 PM   #3
1CleanTJ
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how's the oil level ? low oil could cause it , as well as too much oil ( causes it to foam)

How many miles on the vehicle ?

How are you going by oil pressure, instrument panel or did you hook up a mechanical guage in somewhere ?
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Unread 05-09-2009, 07:09 PM   #4
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Quote:
Originally Posted by 1CleanTJ View Post
how's the oil level ? low oil could cause it , as well as too much oil ( causes it to foam)

How many miles on the vehicle ?

How are you going by oil pressure, instrument panel or did you hook up a mechanical guage in somewhere ?
If he's losing that much oil that quickly, where do you think it's going?
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Unread 05-09-2009, 07:18 PM   #5
1CleanTJ
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Quote:
Originally Posted by GOLENJEEPTJ View Post
If he's losing that much oil that quickly, where do you think it's going?
he's loosing coolant, not oil. He may have a leaky head gasket as well, but that wouldnt cause oil pressure to drop to 0 unless the oil pump is getting to much oil/ or even coolant and causing foaming
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Unread 05-09-2009, 07:34 PM   #6
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Quote:
Originally Posted by 1CleanTJ View Post
he's loosing coolant, not oil. He may have a leaky head gasket as well, but that wouldnt cause oil pressure to drop to 0 unless the oil pump is getting to much oil/ or even coolant and causing foaming
Sorry very stressful day ,lost a dog and I re-read post.
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Unread 05-09-2009, 08:20 PM   #7
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Loosing that much coolant, I would suspect a head gasket or a cracked head. The coolant is leaving as steam, and you cant see it.

Take it to a good shop and ask them to pressure test the cooling system. They could also look for signs of blown gasket by passing an exhaust analyzer of the open neck of the radiator when the engine is hot. The analyzer will detect the CO in the coolant, if it is there.

Curly
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Unread 05-09-2009, 08:38 PM   #8
01TJMudder
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i have the same issues....please let me know what you find out.
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Unread 05-09-2009, 09:17 PM   #9
trick pony
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blown head gasket and cracked head...coolant is gone in the form of steam
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Unread 05-10-2009, 09:29 AM   #10
carlsjeep
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The oil level is between the marks and there is no foaming. I am not losing any oil, only coolant. I have around 120,000 miles on the Jeep and most are highway miles.

The pressure reading is from the guage. I have not had a shot connect an external meter at this time.
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Unread 05-10-2009, 09:34 AM   #11
carlsjeep
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Quote:
Originally Posted by Curly5759 View Post
Loosing that much coolant, I would suspect a head gasket or a cracked head. The coolant is leaving as steam, and you cant see it.

Take it to a good shop and ask them to pressure test the cooling system. They could also look for signs of blown gasket by passing an exhaust analyzer of the open neck of the radiator when the engine is hot. The analyzer will detect the CO in the coolant, if it is there.

Curly
There is a good chance that I do have a cracked head or a leaking head gasket. But it still doesn't explain why I am losing oil pressure. I would like to understand this before working on the coolant loss.
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Unread 05-10-2009, 10:06 AM   #12
Vandano
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If your not getting oil pressure your problems will be more then just burning some coolant. Does your oil light come on when the guage drops? The guage dropping to zero could just be from a bad guage due to another problem.
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Unread 05-10-2009, 10:11 AM   #13
Curly5759
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Quote:
Originally Posted by carlsjeep View Post
There is a good chance that I do have a cracked head or a leaking head gasket. But it still doesn't explain why I am losing oil pressure. I would like to understand this before working on the coolant loss.
I can't think of much of an answer to that, except maybe there is a mechanical problem with the oil pressure relief valve in the pump. Have you put an actual mechanical gauge on it yet? Even with a new sender, there could be electrical issues causing a false reading.

Other thoughts:A defective bypass in the oil filter? Worn engine bearings? Bad Karma? (J/K)

In your first post, you mention that maybe the coolant isn't circulating through the entire engine, overheating the oil. If that were the case, you would have melted a piston or exhaust valve by now.

Curly
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Unread 05-10-2009, 07:13 PM   #14
1CleanTJ
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i'd honestly start by having the oil pressure checked from a mechanical gauge and go from there. most factory dash guages wont show "actual" pressure since it would freak some drivers out etc. as long as you have at least 10psi of oil pressure per 1000 rpm on a mechanical gauge when its hot then I wouldnt worry to much. If you have less, then check into why. Are you running 5w30 oil or ?
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Unread 05-13-2009, 03:37 PM   #15
carlsjeep
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Quote:
Originally Posted by 1CleanTJ View Post
i'd honestly start by having the oil pressure checked from a mechanical gauge and go from there. most factory dash guages wont show "actual" pressure since it would freak some drivers out etc. as long as you have at least 10psi of oil pressure per 1000 rpm on a mechanical gauge when its hot then I wouldnt worry to much. If you have less, then check into why. Are you running 5w30 oil or ?
I am running 20W50 to keep the oil pressure up.
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