Cylinder Wall Scratch
#1
Thread Starter
Newbie
Joined: Sep 2024
Posts: 12
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From: NC
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Cylinder Wall Scratch
Hi guys,
I need some help. So i’ve been hearing a knocking noise coming from the oil pan. I took the spark plugs out and put in the borescope. The pistons seem to have carbon buildup and slight rust. Cylinder #2 wall has 2 vertical scratches and Cylinder #1 has some horizontal dot indents.
I guess my question is how concerned should I be?
Cylinder #2
Cylinder #1
I need some help. So i’ve been hearing a knocking noise coming from the oil pan. I took the spark plugs out and put in the borescope. The pistons seem to have carbon buildup and slight rust. Cylinder #2 wall has 2 vertical scratches and Cylinder #1 has some horizontal dot indents.
I guess my question is how concerned should I be?
Cylinder #2
Cylinder #1
#3
Thread Starter
Newbie
Joined: Sep 2024
Posts: 12
Likes: 5
From: NC
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
#4
Senior Member
Joined: Sep 2016
Posts: 712
Likes: 342
From: North East USA
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
As said earlier that scratch and those strange dents are nothing to worry about, the knocking may be something to worry about.
it might be a secret but could be useful to know how many miles are on the engine and what the oil pressure when it's hot is.
Keep in mind that with your model year the 331 head/ bearings/oil pressure can be an issue.
it might be a secret but could be useful to know how many miles are on the engine and what the oil pressure when it's hot is.
Keep in mind that with your model year the 331 head/ bearings/oil pressure can be an issue.
#5
I dont know about the dots, but it appears to me the bore is showing cross-hatch, so that is either OEM or it has been honed
I guess the vertical scores may be the result on an original non-rebuilt engine that has sucked i small bits of debris over the years
If I was you, I would perform a compression test and monitor oil consumption (easy)
Technically, it would be best to perform a "leak down test" as this will indicate by % whether each cylinder is a pass/fail
I guess the vertical scores may be the result on an original non-rebuilt engine that has sucked i small bits of debris over the years
If I was you, I would perform a compression test and monitor oil consumption (easy)
Technically, it would be best to perform a "leak down test" as this will indicate by % whether each cylinder is a pass/fail
#6
Thread Starter
Newbie
Joined: Sep 2024
Posts: 12
Likes: 5
From: NC
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
As said earlier that scratch and those strange dents are nothing to worry about, the knocking may be something to worry about.
it might be a secret but could be useful to know how many miles are on the engine and what the oil pressure when it's hot is.
Keep in mind that with your model year the 331 head/ bearings/oil pressure can be an issue.
it might be a secret but could be useful to know how many miles are on the engine and what the oil pressure when it's hot is.
Keep in mind that with your model year the 331 head/ bearings/oil pressure can be an issue.
I also did a compression test and each cylinder is giving an about 130-135psi reading
#7
On the face of it I would not consider take apart that motor unless more than 10% below spec...even then probably not, as it will need a complete rebuild
If you are worried about bearing wear, have your oil tested, which will show high levels of certain metals if the bearing is too far worn
Knocks get worse. You should be able to narrow down it source with an engine stethoscope (or screwdriver)
pull one plug at a time gives a clue which cylinder
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