Bad blow by and compression numbers
#1
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Model: Cherokee
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
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
#2
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Join Date: Aug 2011
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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.
This could be as simple as a clogged CCV system. That's the 2 pipes/hoses from the valve cover to air cleaner.
#3
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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?
#6
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Year: 1990
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What do you mean checked through the breather?
#7
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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
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