Gas in oil-compression test - JeepForum.com

 
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post #1 of 6 Old 06-10-2013, 10:22 PM Thread Starter
IslandXJ
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1999 XJ Cherokee 
 
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Gas in oil-compression test

Just changed my oil and went for a 60 mile drive. Now my oil smells of gasoline. The jeep starts and runs great. Does not burn oil and gets 18 mpg. '99 4.0 126k AW4. I just did a dry and wet compression test:
Cylinder Dry Wet

1. 179 221
2. 151 192
3. 168 210
4. 180 224
5. 160 201
6. 181 224

First time checking compression... Warm engine, removed pump and asd relays, WOT, removed plugs. For the wet test I used a turkey injector to put 1/2 oz of oil. These numbers don't look good but I'm seeking some guidance.

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post #2 of 6 Old 06-11-2013, 03:10 PM Thread Starter
IslandXJ
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There is 30 psi difference (~20%) between the cylinder 2 and 6. All the cylinders had higher psi when wet, from 18%-27%. Maybe my gas leak could be caused by a leaking injector?
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post #3 of 6 Old 06-11-2013, 06:59 PM
rjbruzan
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Put a fuel pressure gauge on the fuel rail and it should stay steady when you shut off the engine. If it goes down fast a leaking injector is very possible.

Ron

Of all the things Ive lost
The one I miss most is my mind

Its like a fart in a windstorm
It smells good but thats about it

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post #4 of 6 Old 06-11-2013, 09:16 PM Thread Starter
IslandXJ
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I tested the rail and it had 52 psi. I then just off the ignition and after 10 minutes it dropped to 30 psi and after 25 minutes it dropped to 22 psi. Not sure if this is fast or not.
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post #5 of 6 Old 06-12-2013, 07:12 AM
rjbruzan
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That seems ok. Is it possible you are over sensitive on the gas in oil smell? You are correct in being worried. It is worth getting an oil analysis they are only about 15-25 bucks. A Cat or large truck dealer should have them in stock or call Amsoil and they send them out daily. The bleed down could be an injector or bleedback into the fuel tank which is normal on an older XJ. Also i would not be suprised if you did another cyl test that #2 comes up, maybe the oil hadnt sealed totally.

Of all the things Ive lost
The one I miss most is my mind

Its like a fart in a windstorm
It smells good but thats about it

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post #6 of 6 Old 06-12-2013, 08:15 AM Thread Starter
IslandXJ
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Location: Southeast
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Quote:
Originally Posted by rjbruzan View Post
That seems ok. Is it possible you are over sensitive on the gas in oil smell? You are correct in being worried. It is worth getting an oil analysis they are only about 15-25 bucks. A Cat or large truck dealer should have them in stock or call Amsoil and they send them out daily. The bleed down could be an injector or bleedback into the fuel tank which is normal on an older XJ. Also i would not be suprised if you did another cyl test that #2 comes up, maybe the oil hadnt sealed totally.
The oil definitely smells like gas. When I first did the compression test (dry) i forgot to block open the throttle and #2 was 175psi. After I opened the throttle it showed 151 psi and I retested that 2 more times to make sure the low number was accurate. I do appreciate your idea for an analysis, I need to look into that.
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