• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

92 xj pisten problems

B

b_radley_08

NAXJA Forum User
Location
Salem, Ut
ok i have a 92 xj 4.0. the engine started knocking a couple of months ago. so i strated taring down the engine and everything was looking real good. all the mian bearings are good and the conecting rod bearings are good. the cam is great. the push rods and lifters are great. valves are strate and good. ok this is where things started getting bad. the number one pisten was noticeably worn smaller than the rest and there was a ton of side to side play. so i pulled it out and there was alot of scoring on the side walls of the cylinder. here are my questions what could have caused it and why only the number one cylinder? question number 2 can i hone just that cylinder and replace the pisten with over sized rings? any help or coments are more thank welcome. thank!
 
Any number of things could have caused the piston to damage the cylinder wall, improper sized cylinder, lack of oil, wrong rings, dirt, etc. If there is scoring on the wall you will most likely need a bore and hone, replacing the pistons and rings.

Since it is torn apart I would bore and hone all cylinders and put in new rings and pistons. Have the head checked for flatness, maybe a valve job. Also, replace the bearings. Also, be sure that the lifters go back on the same cam lobe you took them off of. If in doubt you will need a new set of lifters. Same with any used bearing you are going to use, back the same place it came from.
 
ok thanks. i have everything in bags and numbered so i can get them back in there right places. i dont think i am going to replace anything but the number one piston and rings becuase it looks like it has already been rebuilt not to long ago. everything looks brand new and they are all measuring to spec. it looks like who ever rebuilt it did a goog job except for that number one pisten. they must have not put the right size rings in.
 
JJacobs said:
Uh, no. If the cylinder walls are scored it needs to be bored again, and larger pistons installed.
Click to expand...

Agree, scored wall has to be bored, honing won't get it.
 
#1 piston/cylinder is notorious for wear because it heats and cools faster because of the water pump on the front side of it.

I had a 87 and noticed compression loss on #1, but was in no hurry to address it as the Jeep would get 23mph on the Hwy. Finally decided to get to it, so I put a reman long block in and never saw better then 18mph but got better compression!!
 
Sig220 said:
but was in no hurry to address it as the Jeep would get 23mph on the Hwy.
Click to expand...

I think I was stuck behind you once between Denver and Tucson! :confused1
 
b_radley_08 said:
ok thanks for all of your help.i guess i am sending it to a machien shop.
Click to expand...
Hold on there pardner...

You wanted to fix just the #1, right?

The engine was running, right?

If on a budget, hone it, put in a new piston and rings and put er back together, just like a dirt bike.

But, do not put larger rings on a standard cylinder, they will not fit into the grooves with enough overlap, and, they most likely will not stay "round" if too big for the cylinder.
 
actually i was kinda thinking i would try exactly that. i cant afford to buy a new engine or get it worked on. the jeep was running great before. the only reason i tore it apart was cause the knock was bugging me. pluss the number one cylinder had more than 120 psi compression. i can live with that.
 
joe_peters said:
I think I was stuck behind you once between Denver and Tucson! :confused1
Click to expand...


Behind a smoker??? Really did not smoke......unlike my current 92 "Hoopty" in a 2000 mile roundtrip, she used 1 gallon of oil!!! Of course it leaks a little......its got a "blow by" problem and if you reseal the valve cover it will leak out the pan....reseal the pan and it pops out the valve cover!!!
 
ok here is the update. i did decide to replace just the number one piston and rings. i bought a new one from a machine shop and they put it on the conecting rod for me. i honed the cylinder and it looked really good. there were still some light up and down scratches but i got them out the best i could. i put it all back together and it runs GREAT!!! i have 120 psi in all my cylinders and it runs smooth and quite. thanks everyone for you help
 
Talyn said:
Let us know how long it holds up. Not saying that it will fail or anything, just interested in if this will be a permanent fix.
Click to expand...

Me too, keep us updated over the next several months. :eyes:
 
will do. i am worried about it myself. but as long as it lasts tell next summer i am ok with it. keep in mind i jumped on top of the problem way early. i dont think it would have worked as well if i had waited much longer.
 
In all likelyhood it will be fine depending on the rings you used. As nice as perfect is, there is often more tolerance that one would expect. If the cylinder was round and not oblong, a few shallow scores will not make a huge mount of difference. They will fill with carbon anyway.
 
You must log in or register to reply here.

Similar threads

M
92 XJ ECU connector
Replies
5
Views
138
Rob Mayercik
R
O
0331 Strikes Again...?
Replies
11
Views
301
Ol Blue
O
O
2000 XJ Failed Colorado Emissions high CO
2
Replies
27
Views
2K
Ken M
K
M
Pedal goes to floor when turned on
Replies
0
Views
507
Myziric
M
V
Xj broke down while traveling
2 3 4
Replies
64
Views
8K
Vitzaa
V
Back
Top