wingtime
NAXJA Forum User
- Location
- Clearwater, FL
First off I'd like to say that I am new to the group. I look forward to sharing lots of XJ info with all of you!
Ok on to my problem.
I have a 90 XJ 4.0 w 167K miles on it.
It runs like a raped ape and has good oil pressure but it has what was thought to be a rod knock. I did a archive search and looked at the usual suspects. The flex plate and bolts were fine. I pulled one plug wire at a time and no change.
To find out what was going on, I went ahead and pulled the oil pan and checked the rod bearings. They were worn but I didn't really see one that looked bad enough to knock. While I had each rod apart I pushed each piston up and down to check for play in the wrist pins. They all seamed nice and tight. I went ahead and replaced the rod bearings while I was in there and used a plasti guage to check the clearance. I pulled one main bearing cap and put it back since the main looked very good. While in there I noticed the timing chain had quite a bit of slack in it. So I replaced that too. Since I had it apart I decided to go ahead and put in a new high flow oil pump as well. After all of that I wrestled the oil pan back on.
Once everything was back together we fired up the jeep... Knock knock knock! Darn!
I know piston slap is common on these jeeps, but if it is that it's only one cylinder.
After using a wooden dowl to listin for the sound it apears to be comming from the rear of the head and we now think it is in the valve train. I pulled the valve cover and checked each rocker with it running and I doubt it is a lifter.
I'm at the end of my rope here! any ideas or suggestions for what I have missed here? Any help would be greatly appreciated.
Bruce Smith
Ok on to my problem.
I have a 90 XJ 4.0 w 167K miles on it.
It runs like a raped ape and has good oil pressure but it has what was thought to be a rod knock. I did a archive search and looked at the usual suspects. The flex plate and bolts were fine. I pulled one plug wire at a time and no change.
To find out what was going on, I went ahead and pulled the oil pan and checked the rod bearings. They were worn but I didn't really see one that looked bad enough to knock. While I had each rod apart I pushed each piston up and down to check for play in the wrist pins. They all seamed nice and tight. I went ahead and replaced the rod bearings while I was in there and used a plasti guage to check the clearance. I pulled one main bearing cap and put it back since the main looked very good. While in there I noticed the timing chain had quite a bit of slack in it. So I replaced that too. Since I had it apart I decided to go ahead and put in a new high flow oil pump as well. After all of that I wrestled the oil pan back on.
Once everything was back together we fired up the jeep... Knock knock knock! Darn!
I know piston slap is common on these jeeps, but if it is that it's only one cylinder.
After using a wooden dowl to listin for the sound it apears to be comming from the rear of the head and we now think it is in the valve train. I pulled the valve cover and checked each rocker with it running and I doubt it is a lifter.
I'm at the end of my rope here! any ideas or suggestions for what I have missed here? Any help would be greatly appreciated.
Bruce Smith