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Unread 03-21-2012, 12:13 PM   #1
xjgary
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Gas in the oil pan

I am getting massive amounts of gas in the oil pan of my 1992 Cherokee and can't seem to find how it's getting there. With just ten miles on a fresh oil change the dipstick is already above the full, safe line. any suggestions would be greatly appreciated.

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Unread 03-21-2012, 12:18 PM   #2
tdavid14
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I don't know if it's the same, but my old chevy had a mechanical fuel pump that ruptured and dumped gas into the oil.
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Unread 03-21-2012, 01:44 PM   #3
Foundrydude
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92 is fuel injected, right?

One (or more) of your injectors is leaking down big time and the piston ring seal is so poor it's running down into the crank case. I'm guessing it also smokes like a burning house when you get on it.

If it's carbureted, definitely look at the fuel pump as noted above. That's the most likely cause.

good luck
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Unread 03-21-2012, 02:47 PM   #4
Ross00TJ
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Originally Posted by Foundrydude View Post
92 is fuel injected, right?

One (or more) of your injectors is leaking down big time and the piston ring seal is so poor it's running down into the crank case. I'm guessing it also smokes like a burning house when you get on it.

If it's carbureted, definitely look at the fuel pump as noted above. That's the most likely cause.

good luck
This.

If it is fuel injected then I would check to see if your injectors are leaking and run a compression test to see the state of your piston rings.
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Unread 03-22-2012, 06:33 AM   #5
xjgary
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That's the weird thing, the eingine runs GREAT and has never smoked or used oil. My first thought also was a leaking injector so I replaced all injectors which did not help. My next guess was maybe the vacuum controlled fuel pressure regulator was leaking and changed that. With a fresh oil change and new regulator the oil level is already rising after only 10 miles of driving. I will do a compression check this week end.
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Unread 03-22-2012, 08:26 AM   #6
jnicewan
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I really cant see how you are getting that much fuel into the crankcase without have a dead cylinder and/or a lot of smoke. I have seen injectors leak or stuck wide open and cause this but most of the fuel would be pumped out through the exhaust. Unburned fuel (a lot of it) would be light grey or white, excessively rich would be black. Are you sure its fuel, can you put a lighter to the dipstick and catch it on fire?
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Unread 03-22-2012, 09:35 AM   #7
xjgary
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I'm serious the engine runs great. absolutely no smoke . no oil consumption or lack of power. It starts and runs great. I have also replaced the spark plugs. Although worn there where no signs of fouling,miss fire or excessive oil burning. they looked quite normal.Coolent levels are stable so it's not antifreeze. I haven't tried lighting the oil on fire but at the last oil change the oil was coffee colored and smelled strongly of gasoline. I am completely puzzled.
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Unread 03-22-2012, 12:24 PM   #8
Ross00TJ
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Quote:
Originally Posted by xjgary View Post
That's the weird thing, the eingine runs GREAT and has never smoked or used oil. My first thought also was a leaking injector so I replaced all injectors which did not help. My next guess was maybe the vacuum controlled fuel pressure regulator was leaking and changed that. With a fresh oil change and new regulator the oil level is already rising after only 10 miles of driving. I will do a compression check this week end.
Are you sure the oil isn't rising just because it is hot? It does that you know...

How do you know it's fuel in the oil and not something else? The only way for fuel to get in the crankcase (at this point) is past the pistons. Does it make a rattle noise mid-engine on start-up that goes away as it warms up, if so you may want to check for a cracked piston skirt / piston.

I say that you invest in a new head gasket, head bolts, and oil pan gasket and take the head off and drop the pan. The only way you'll ever know what's going on is by taking a look for yourself (or while performing the autopsy after it goes boom). We can all theorize but that's all it is, theories, you have to prove or disprove them. If you need second opinions then post pictures.

Run the compression test and maybe a leak down test while you're at it and then tear into the engine to see what's really going on.

MHO.
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Unread 03-22-2012, 04:23 PM   #9
Idwheelthat
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I would run the engine for a few minutes, shut it off and check sparkplugs to see if any are wet with gasoline. Reinstall plugs after engine cools down. Perhaps it's going through the charcoal emission filter into the pcv system.
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Unread 09-13-2013, 07:57 AM   #10
xjgary
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I still haven't figured this one out After doing a compression test that seems normal for a vehicle of this age ( low of 135 lbs. - high of 145 lbs.) and changing the fuel pump as suggested by a fellow forum member who was experiencing the same problem and found this to be his cure, still no luck. Tried blocking the vacuum line to the charcoal emission canister, no improvement. So out of frustration parked the 92 Cherokee to avoid completely destroying the engine. In the mean time I have been driving my other 2001 Jeep Cherokee exclusively. Guess what? Out of the blue the 2001 has started doing the EXACT SAME THING!!!! WTF is going on with these Jeeps?? Has no one else experienced this with the 4.0 ? I am SO frustrated I am ready to send them both to the crusher!! Any ideas ?
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Unread 09-13-2013, 10:09 AM   #11
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Do you have a buddy who is a wicked practical joker?

If it is fuel there are very few ways for it to get into the oil, less if your plugs are still looking dry.

The ONLY thing I have ever seen cause this was a holed mechanical fuel pump diaphram. There should be no vacum in the crankcase to suck fuel in and if it gets pushed past the rings the plugs would show it.
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Unread 09-14-2013, 08:03 PM   #12
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Quote:
Originally Posted by xjgary View Post
I am getting massive amounts of gas in the oil pan of my 1992 Cherokee and can't seem to find how it's getting there. With just ten miles on a fresh oil change the dipstick is already above the full, safe line. any suggestions would be greatly appreciated.
You say you have a FSJ Cherokee do you mean a Grand Cherokee with the 5.9 engine? IF you do then your mechanical fuel pump is the culprit.
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Unread 09-16-2013, 06:47 AM   #13
xjgary
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No, I'm not talking about a Grand Cherokee with the 5.9 . I own two Jeep Cherokees with the 4.0 H.O. engine and now both are experiencing the same gas in the oil issue. It is not a small amount that I'm talking about either. I'm getting close to a quart increase in the oil pan in less than forty miles on a fresh oil change. The oil reeks of gasoline and there is absolutely no loss of engine coolant. Every attempted remedy was followed with a fresh oil change which lead to another 40 miles and a increase of about a quart in the oil pan with absolutely no loss of engine coolant. Compression check is normal which to me rules out bad rings or a blown head gasket. What could possibly be causing this? I live in a remote northern climate near Lake Superior and a dependable 4 wheel drive is a must.
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Unread 09-16-2013, 08:00 AM   #14
laybackman
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Quote:
Originally Posted by xjgary View Post
No, I'm not talking about a Grand Cherokee with the 5.9 . I own two Jeep Cherokees with the 4.0 H.O. engine and now both are experiencing the same gas in the oil issue. It is not a small amount that I'm talking about either. I'm getting close to a quart increase in the oil pan in less than forty miles on a fresh oil change. The oil reeks of gasoline and there is absolutely no loss of engine coolant. Every attempted remedy was followed with a fresh oil change which lead to another 40 miles and a increase of about a quart in the oil pan with absolutely no loss of engine coolant. Compression check is normal which to me rules out bad rings or a blown head gasket. What could possibly be causing this? I live in a remote northern climate near Lake Superior and a dependable 4 wheel drive is a must.
Now BOTH of your 4.0's are doing this!? Did you do anything to one unit then did it to the second one?

I mean, what are the odds? The only other things they have in common other than ownership and geography is their fuel source and repairs.

My first guess would be classic ring wash which means unburned fuel in the cylinders washing down into the base pan.

Since your 4.0's are have in tank fuel pumps I'd look at fuel pump pressure at the rail. Maybe your fuel pump regulator(s) have lost their vacuum source which would jack up your fuel pressure. Did you do anything to their vacuum source?
Last but not least is old leaking fuel injectors that allow unburned fuel to leak into the cylinders between firing cycles.
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Unread 09-16-2013, 10:50 AM   #15
xjgary
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I haven't made any changes to vacuum sources other than isolating the charcoal emission canister to see if fuel was entering the intake in this matter but to no avail so reattached vacuum to this port. As mentioned earlier, all fuel injectors where replaced in the 1992 which was the first to exhibit this problem. I haven't attempted any repairs on the 2001 seeing I have invested so much time and expense with the first with no successes and am on a tight budget. I am dreading throwing parts at the 2001 until I can figure out what is up with the 92. I have changed the fuel pressure regulator on the fuel rail, is the fuel pump regulator a different part? If so, where is it located? I will see if I can locate a fuel pressure gauge and measure the pressure at the rail. Do you think it could be bad fuel coming from the local gas station? We only have one and the next nearest is 25 miles away. Could it be the Engine Computer?

Thanks for your input
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