Help Diagnosing Engine Knock
- Thread starter The Goblin
- Start date
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- engine knock flex plate
I never said to anybody in here to not check their timing chain. I never told anybody that's not their problem. I'm only sharing my troubleshooting experience, what I found and what I believe to be my issue, right or wrong. The OP checked bearing clearances and changed his timing chain to no avail. Did that stop me from doing the same to my Jeep? No.
I only stated that my noise did not get any better. I'm trying to share as much information as I can to help others.
Looks like I missed this question. My manifold was the two piece design and had no cracks. I'm guessing they changed from a one piece to a two piece because of the cracking? No idea but it was in good shape.
Has anybody noticed the sound being worse after an oil change? I just changed my oil and I swear the sound is louder and taking longer to subside. I also believe that when I bought this Jeep last year that I didn't even notice a sound until I did my first oil change to it.
I can't imagine how putting clean oil in it is causing a change but this isn't the first time I've noticed a change.
I can't imagine how putting clean oil in it is causing a change but this isn't the first time I've noticed a change.
[Engine knock/slap resolved]
Okay, this post is going to be winded because it's about a weeks worth of information in one. As my last post said, I recently changed my oil and the sound was more prominent and took longer to subside. This pushed me to the point of ordering a set of pistons.
I understand this isn't the 100% correct way to do what I've done but this is what I was willing to invest financially, physically and mentally to try and fix this slap/knock noise. I'm sharing to help people make their own decision but your mileage may vary.
My goal going into this was to order a set of standard pistons/rings, deglaze the cylinders and reuse all of my gaskets minus the head gasket. The gaskets have all been replaced 2,000 miles ago from my cam/lifters swap and the head bolts, according to the manual can be used twice. I planned on doing all of this in-frame and basically shade-tree slap some pistons in it and call it a day. Don't get too invested, don't stress measuring everything and checking tolerances, etc.
I ordered a set of sealed power standard pistons from ebay that included a Mahle piston ring set.
I started the tear down which didn't take too long since just 2k miles ago I had it apart replacing the cam and other components.
None of the pistons had cracked skirts. Just a note, this engine is from a 2003 although the Jeep is a 2001. Not sure if that plays a part but I ran the block numbers and it's a 2003 and has the TUPY head.
The skirts had a fair amount of wear but the cylinders looked fairly good. There was still cross hatching but there was also some glazing.
I planned on pressing the pins out of the connecting rods myself and heating the rods and installing the new pistons myself, also. In the end I did press them out with a 20 ton press but decided to have a local machine shop install the pistons for $80.
I usually take so many pictures but I failed to get pictures of the wrist pins and their condition. I couldn't feel any slop in the wrist pin when they were installed but after pressing them out they had a good amount of wear that you could feel with your finger and see. Some of the pins after pressing the rod off actually fell out of the pistons and hit the ground.
This basically destroyed the pistons but I had no plans of keeping them.
I ended up ordering a new oil pan gasket and manifold gasket just to be sure I didnt have to do it again (see more below)
Trying to keep this short and to the point, haha. I worked on it for 8.5 non stop last night to get it together. Fired it up today around noon. Fired right up, no noise. Ran it through some RPM ranges and shut it down to top off the coolant. Fired it up again and drove it around the block. Topped off coolant as needed and seen it was performing well enough to take it on an 80 mile journey (lol).
I've don't hot starts, mostly cold starts and I haven't heard the noise once. There's also noises that are gone that I didnt even know I had. I previously mentioned a noise while shifting gears that sounded like a power steering while, possibly. It was jn fact the pistons/pins, the noise is completely gone. The jeep sounds so much better. The bad news is I rushed the oil pan gasket and it's leaking pretty well out the back. I've confirmed it isn't the valve cover gasket.
Anyways, I do believe the problem is fixed and I did it for under $400, I think? (Excluding all the previous repair, of course). The question now is longevity and if my repair was done well enough to last. Tomorrow will be the first cold morning start but I'm confident it's going to do just fine.
I'll update and can post videos if anybody is interested and if the fix doesn't reverse itself. Hope this helps.
Okay, this post is going to be winded because it's about a weeks worth of information in one. As my last post said, I recently changed my oil and the sound was more prominent and took longer to subside. This pushed me to the point of ordering a set of pistons.
I understand this isn't the 100% correct way to do what I've done but this is what I was willing to invest financially, physically and mentally to try and fix this slap/knock noise. I'm sharing to help people make their own decision but your mileage may vary.
My goal going into this was to order a set of standard pistons/rings, deglaze the cylinders and reuse all of my gaskets minus the head gasket. The gaskets have all been replaced 2,000 miles ago from my cam/lifters swap and the head bolts, according to the manual can be used twice. I planned on doing all of this in-frame and basically shade-tree slap some pistons in it and call it a day. Don't get too invested, don't stress measuring everything and checking tolerances, etc.
I ordered a set of sealed power standard pistons from ebay that included a Mahle piston ring set.
I started the tear down which didn't take too long since just 2k miles ago I had it apart replacing the cam and other components.
None of the pistons had cracked skirts. Just a note, this engine is from a 2003 although the Jeep is a 2001. Not sure if that plays a part but I ran the block numbers and it's a 2003 and has the TUPY head.
The skirts had a fair amount of wear but the cylinders looked fairly good. There was still cross hatching but there was also some glazing.
I planned on pressing the pins out of the connecting rods myself and heating the rods and installing the new pistons myself, also. In the end I did press them out with a 20 ton press but decided to have a local machine shop install the pistons for $80.
I usually take so many pictures but I failed to get pictures of the wrist pins and their condition. I couldn't feel any slop in the wrist pin when they were installed but after pressing them out they had a good amount of wear that you could feel with your finger and see. Some of the pins after pressing the rod off actually fell out of the pistons and hit the ground.
This basically destroyed the pistons but I had no plans of keeping them.
I ended up ordering a new oil pan gasket and manifold gasket just to be sure I didnt have to do it again (see more below)
Trying to keep this short and to the point, haha. I worked on it for 8.5 non stop last night to get it together. Fired it up today around noon. Fired right up, no noise. Ran it through some RPM ranges and shut it down to top off the coolant. Fired it up again and drove it around the block. Topped off coolant as needed and seen it was performing well enough to take it on an 80 mile journey (lol).
I've don't hot starts, mostly cold starts and I haven't heard the noise once. There's also noises that are gone that I didnt even know I had. I previously mentioned a noise while shifting gears that sounded like a power steering while, possibly. It was jn fact the pistons/pins, the noise is completely gone. The jeep sounds so much better. The bad news is I rushed the oil pan gasket and it's leaking pretty well out the back. I've confirmed it isn't the valve cover gasket.
Anyways, I do believe the problem is fixed and I did it for under $400, I think? (Excluding all the previous repair, of course). The question now is longevity and if my repair was done well enough to last. Tomorrow will be the first cold morning start but I'm confident it's going to do just fine.
I'll update and can post videos if anybody is interested and if the fix doesn't reverse itself. Hope this helps.
I'm not sure if it's solely the pins. My noise was not present when first starting but came after about 30 seconds and slowly faded. I was thinking maybe the piston being aluminum is expanding faster than the pins causing an excess tolerance and noise. After a few minutes of running the steel pin heats up and closes the tolerance and the noise mostly subsides.
I'm no engineer and it's above my head all I know is I'm stoked because it sounds so much better but I'm also very scared that it's not going to last. *crosses fingers*
fourpointzero
TJ Addict
This thread has been very interesting to read, and I really appreciate all of you who have done work, posted pics and results.
I think the conclusion I've made, is that I'm going to live with the noise and drive it til it dies. I will be ready financially for an LS, stroker or rebuild when it dies.
I think the conclusion I've made, is that I'm going to live with the noise and drive it til it dies. I will be ready financially for an LS, stroker or rebuild when it dies.
fourpointzero
TJ Addict
@Gibsonfirebird12 lol, "when it dies". Im hoping an electric engine kit is available in the not-to-distant future. 
May never die. Who the hell knows!@Gibsonfirebird12 lol, "when it dies". Im hoping an electric engine kit is available in the not-to-distant future.
OP
This is really amazing! The sound it makes after (or the lack thereof) is simply beautiful. Thanks for sharing what you did. Sounds like wrist pins are definitely on the list of potential culprits then.
OP
What? You don't like the idea of dropping $200 just to fill up your gas tank soon??@Gibsonfirebird12 lol, "when it dies". Im hoping an electric engine kit is available in the not-to-distant future.
OP
Anyone checked their thrust bearing clearance by chance? I neglected to check mine while I had the oil pan off and it's bothered me ever since. Could potentially cause a rattle if the crank is bouncing back and forth.
Although I don't know how that would fit in with the quiet-then-loud-after-30-seconds symptom...
Although I don't know how that would fit in with the quiet-then-loud-after-30-seconds symptom...
OP
That's me! Glad you found the thread! Thanks for sharing your experience as well!
fourpointzero
TJ Addict
Shyt, Im one of the fortunate people who WFH. And I still lose my effing mind seeing the dollars pile up while only putting in half a tank!What? You don't like the idea of dropping $200 just to fill up your gas tank soon??