old_man
NAXJA Forum User
- Location
- Loveland, Colorado
I've seen that happen when the flex plate was put back on without the big "washer" that goes over all the holes at once.
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Not your average engine knock
- Thread starter laredo
- Start date
- Location
- Torrance, CA
The washer was in place and it cracked just on the outside of it.
Update
I have done two oil changes since I posted last. It's still been less than 2k though. I tried switching oil filters, ran a quart of Marvel Mystery Oil with my oil and just the other day switched to Rotella t6 5-w40 with still no change to the knock.
I just went outside and disconnected injectors one by one and there is a noticeable change in the knock when I remove #6. Am I looking more at a broken piston skirt now? Any more things I can check without dropping the pan? The knock hasn't gotten any worse but it's enough of a concern that I want to get it resolved. Only other thing I've noticed is that it will give a slight intermittent knock while not giving it throttle but it's only a single knock maybe once every minute or so, otherwise it only knocks at about 1500rpm. Any chance this could be spark knock or is that more high pitched? I believe I might have done the plugs at around the same time I noticed the knock. Thanks in advance for any insight.
I have done two oil changes since I posted last. It's still been less than 2k though. I tried switching oil filters, ran a quart of Marvel Mystery Oil with my oil and just the other day switched to Rotella t6 5-w40 with still no change to the knock.
I just went outside and disconnected injectors one by one and there is a noticeable change in the knock when I remove #6. Am I looking more at a broken piston skirt now? Any more things I can check without dropping the pan? The knock hasn't gotten any worse but it's enough of a concern that I want to get it resolved. Only other thing I've noticed is that it will give a slight intermittent knock while not giving it throttle but it's only a single knock maybe once every minute or so, otherwise it only knocks at about 1500rpm. Any chance this could be spark knock or is that more high pitched? I believe I might have done the plugs at around the same time I noticed the knock. Thanks in advance for any insight.
soilman
NAXJA Forum User
- Location
- Vincennes, IN
I know every jeep I've ever owned with the 4.0L rattles and knocked sounds like a diesel engine I figure it is noisy lifters and piston slap as well. Old jeeper but new back At these forums. What is MMO?
Sidewinder CC
NAXJA Forum User
- Location
- Canton, Michigan
With such low mileage engine it's probably not your issue but if you find time, remove your distributor cap and see how much play is in your rotor shaft - side to side, up and down, and rotational. There may be damage under the cap so look for it as well.
Next place I would look is under the valve cover. Checking the valve springs.
Edit: Also, check security of the four bolts holding the bell housing to the engine block.
Next place I would look is under the valve cover. Checking the valve springs.
Edit: Also, check security of the four bolts holding the bell housing to the engine block.
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
Pull the plugs and post up the pix. #6 cylinder could be carboned up and causing detonation. While you have them out, do a compression test, both dry and wet.
Transpoquick
NAXJA Forum User
- Location
- illinois
I would agree w/ removing the valve cover and looking for broke or loose "parts".
Cherokee knock 2 doesn't sound like the typical 4.0 knock, sounds like its missing too.
First though, pulling the plugs and reading them would be a good idea.
Loose flex plate to torque converter bolts make lots of noise on deceleration like a bad u-joint, slip yoke or c.v. driveshaft.
Hope its not a bottom end problem w/ that kind of mileage, that would suck!
Cherokee knock 2 doesn't sound like the typical 4.0 knock, sounds like its missing too.
First though, pulling the plugs and reading them would be a good idea.
Loose flex plate to torque converter bolts make lots of noise on deceleration like a bad u-joint, slip yoke or c.v. driveshaft.
Hope its not a bottom end problem w/ that kind of mileage, that would suck!
I thought my new engine was having rod knock. bad noises. I was positive it was something in the engine. I noticed that the "knocking" went away when put into gear.
I pulled the transmission plate and looked at the flex wheel. I used a light, and sure enough, its cracked. I had to rotate the engine to find em. Sucks, cause the flex plate is less then $50, and I just had my transmission rebuilt 3 weeks ago. Now I have to pull it down, again.
snake camera connected to my Phone:
I pulled the transmission plate and looked at the flex wheel. I used a light, and sure enough, its cracked. I had to rotate the engine to find em. Sucks, cause the flex plate is less then $50, and I just had my transmission rebuilt 3 weeks ago. Now I have to pull it down, again.
snake camera connected to my Phone:
Yea, I just watched your videos.
That is the EXACT sound my Jeep makes. Exact. It's not a rhythmic sound, as in a constant sound. Its more of a random clanking sound. If you put your finger on the intake, you can fill the vibrations.
You really need to inspect the flex plate
That is the EXACT sound my Jeep makes. Exact. It's not a rhythmic sound, as in a constant sound. Its more of a random clanking sound. If you put your finger on the intake, you can fill the vibrations.
You really need to inspect the flex plate
Sidewinder CC
NAXJA Forum User
- Location
- Canton, Michigan
Sounds like it's #6 cylinder giving you the problem.
Compression check.
Compression loss check (air escaping from the TB or exhaust=valve issues.
White spark plug electrodes =lean burning.
I need to get a compression tester this weekend but I at least pulled the plugs. They seemed fine. This is the one from the #6 cylinder. It seemed the same as the others. I ran it again for about 20 minutes while disconnecting the fuel injectors. I think there's a definite change in the knock when I remove #6 but I don't think it goes away completely.
https://drive.google.com/file/d/0B8I13V03Sl2Eb29jTTM5TS1KckU/view?usp=docslist_api
https://drive.google.com/file/d/0B8I13V03Sl2ESndETVVpVUhBX0E/view?usp=docslist_api
https://drive.google.com/file/d/0B8I13V03Sl2Eb29jTTM5TS1KckU/view?usp=docslist_api
https://drive.google.com/file/d/0B8I13V03Sl2ESndETVVpVUhBX0E/view?usp=docslist_api
Last edited:
harmonic frequency changing by removing a cylinder from the loop. changing the why the flex plate gets bent during idle.
Does the noise go away or almost go away when put in gear?
It takes about 30 min the inspect the flex plate. You want to look for shiny lines, or dark back lines if they filled with oil and grime. I too was skeptical young grass hopper. I was sure my freshly built stroker was rattling.
search "Rod Knock" or "engine rattle" or something like that, and most all the solutions end up being the flex plate, not the engine.
King,
The knock doesn't go away in gear. It stays the same in all gears.It's mainly on light acceleration that it's heard. It's pretty much only at the 1200-1500 rpm range. It's nonexistent after that.
I pulled the inspection cover off and didn't see any cracks and bolts were tight. If this was a crack it would be up around the center which I'd have to drop the tranny to see.
I've literally watched every Jeep noise,rattle and knock video on youtube after hours upon hours and I haven't found one that matches mine. The closest would be a flex plate crack but I'm not sure now since removing cylinder #6 softens the knock.
I didn't want to have to drop the tranny and pay for that job unless I was sure and now I'm leaning towards it not being the flex plate. It's pretty much driven me to my whits end. I searched for far too long to find one this nice and I want to be pro-active and not have a rod go through the block,especially with only 68k. I truly do appreciate you and the other guys posting on this thread a lot. This is where I come for smart Jeep people and not the 10 million idiots responding on Facebook and Youtube.
The knock doesn't go away in gear. It stays the same in all gears.It's mainly on light acceleration that it's heard. It's pretty much only at the 1200-1500 rpm range. It's nonexistent after that.
I pulled the inspection cover off and didn't see any cracks and bolts were tight. If this was a crack it would be up around the center which I'd have to drop the tranny to see.
I've literally watched every Jeep noise,rattle and knock video on youtube after hours upon hours and I haven't found one that matches mine. The closest would be a flex plate crack but I'm not sure now since removing cylinder #6 softens the knock.
I didn't want to have to drop the tranny and pay for that job unless I was sure and now I'm leaning towards it not being the flex plate. It's pretty much driven me to my whits end. I searched for far too long to find one this nice and I want to be pro-active and not have a rod go through the block,especially with only 68k. I truly do appreciate you and the other guys posting on this thread a lot. This is where I come for smart Jeep people and not the 10 million idiots responding on Facebook and Youtube.
- Location
- Salem, OR
How's the exhaust hanger bushings? Have you checked the clearance of the exhaust tube going between the crossmember and floor?
outlander
NAXJA Forum User
- Location
- Columbus,Ohio
subscribed out of curiosity for the outcome...
im gonna take a shot in the dark too and say exhaust hitting cross member or something (could very well be a flex plate though)
im gonna take a shot in the dark too and say exhaust hitting cross member or something (could very well be a flex plate though)