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Bad blow by and compression numbers

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Old 03-13-2016, 09:58 PM
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Default Bad blow by and compression numbers

i bought a 95 keep xj manual and looked at engine surrounding area for oil leaks. The guy assured me there were none. I drove it around the block and checked 4 wheel dr ect.. I popped the hood when I got back and looked again nothing bad seen. the jeep started leaking lots of oil out of dipstick tube after driving for about 45 minutes and higher speeds. I replaced the CCV and did a compression test.

My numbers were:
Cold-
#1. 97PSI
#2. 100PSI
#3. 99PSI
#4. 108PSI
#5. 105PSI
#6. 102PSI

Hot
#1. 103PSI
#2. 118PSI
#3. 111PSI
#4. 112PSI
#5. 120PSI
#6. 114PSI

I've read to multiply highest by .15 and deduct that number from your highest reading and if in that range your good. 103# is in the range but barely. In a 4 hour drive I'm losing 1 quart of oil and creates a fire hazard smoking awful. Any suggestions? I also pulled the oil cap off running and it had a vacuum at idle. Any suggestions are appreciated thanks. I also went back and put a little oil on the Pistons and retested. It raised my numbers by about 12PSI
Old 03-14-2016, 09:12 AM
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I wouldn't condemn it just yet.

This could be as simple as a clogged CCV system. That's the 2 pipes/hoses from the valve cover to air cleaner.
Old 03-14-2016, 10:10 AM
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I read the specs are suppose to be 150 to 120PSI. I just didn't know if all the rings would fail at the same time. I don't see any blue smoke when it's idling. I checked through the breather and it was clear. There's not much else it could be is there?
Old 03-14-2016, 11:09 AM
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Either flip the Jeep (sell it) or pull the engine for a total rebuild.
Old 03-14-2016, 11:38 AM
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10-4 Thats what I thought. Thanks
Old 03-14-2016, 05:27 PM
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Originally Posted by Jeremy313
I read the specs are suppose to be 150 to 120PSI. I just didn't know if all the rings would fail at the same time. I don't see any blue smoke when it's idling. I checked through the breather and it was clear. There's not much else it could be is there?
What do you mean checked through the breather?
Old 03-14-2016, 05:39 PM
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I apologize I pry have the wrong name for the piece. I was talking about the elbow that is basically the same part as the CCV on the head cover that has a hose connected to the airbox. I just disconnected the hose and blew through the hose and air could pass through
Old 03-14-2016, 06:05 PM
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doing a legitimate leak down test will pinpoint the problem.
Old 03-14-2016, 06:24 PM
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I'll try that next. thanks
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