Knocking Noise-Possible Flexplate - JeepForum.com
 
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post #1 of 14 Old 05-01-2014, 10:00 AM Thread Starter
skisprinkle686
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1999 WJ 
 
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Knocking Noise-Possible Flexplate

So I have a horrible knocking noise coming from the driver's side of my 99 4.0. Thought it might the pistons or crank but I called my local mechanic who happens to be a big Jeep guy and he says he will almost bet its the flywheel or flexplate (not sure which is the correct name).

He said if the noise gets quieter as you step on the gas then that is a dead give away. Mine does that exact same thing. I am going to try and upload a video of it tonight or tomorrow to get everyone's feedback. Is this something common and what are your thoughts on that being the problem?

Thanks guys!


1999 WJ 4.0L V6 Limited
Rusty's 2.0" Lift
Flowmaster 40
Surco Roof Rack
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post #2 of 14 Old 05-01-2014, 12:58 PM
harkinsc
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2004 WJ 
 
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I just replaced my flexplate, torque converter, and bolts on my 4.7L. The rattle / knock was audible from idle to 2500 rpm just as you describe. 3 out of 4 of my flexplate-torque converter bolts had backed out of the torque converter and were rubbing on the back of the block and dust shield. If this is indeed your problem don't just try to tighten the bolts back in as they could be stripped. Just replacing the bolts may not be the best idea either. Carefully inspect the flexplate and torque converter for damage. My issue had gone on long enough to cause some serious wear and deformation on the flexplate and torque converter. See my thread: http://www.jeepforum.com/forum/f310/...knock-2164393/
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post #3 of 14 Old 05-01-2014, 01:36 PM Thread Starter
skisprinkle686
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I'm for sure going to just replace the flexplate I am just wondering if I should mess with the crank, bearings or pistons while I'm at it? Or if I should just replace that first and see what happens.

1999 WJ 4.0L V6 Limited
Rusty's 2.0" Lift
Flowmaster 40
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post #4 of 14 Old 05-01-2014, 03:20 PM
Fellows45
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Quote:
Originally Posted by skisprinkle686
So I have a horrible knocking noise coming from the driver's side of my 99 4.0. Thought it might the pistons or crank but I called my local mechanic who happens to be a big Jeep guy and he says he will almost bet its the flywheel or flexplate (not sure which is the correct name). He said if the noise gets quieter as you step on the gas then that is a dead give away. Mine does that exact same thing. I am going to try and upload a video of it tonight or tomorrow to get everyone's feedback. Is this something common and what are your thoughts on that being the problem? Thanks guys!
I have this same problem I believe! If I give it some gas at idle it seems to go away! Can you upload a video still! This would help me diagnose my problem. How much could something like this run to fix? Is it a DIY? Thanks I'll take all the info I can get!

2002 Jeep WJ, 4.7, EBC Stage 4 brakes, Bilstein shocks (Still In progress)

1989 Wrangler YJ 2.5, 2 inch body lift, 33 inch tires
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post #5 of 14 Old 05-02-2014, 08:46 AM Thread Starter
skisprinkle686
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So I was able to get two videos this morning during warm up. The first video is from the top. The second is from just beside the drivers side shock. I still think it's more than a flexplate. Any ideas?

https://www.youtube.com/watch?v=6SXsEXRP-Ls

https://www.youtube.com/watch?v=RMHEWKxpxZQ

1999 WJ 4.0L V6 Limited
Rusty's 2.0" Lift
Flowmaster 40
Surco Roof Rack
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post #6 of 14 Old 05-02-2014, 11:32 AM
harkinsc
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Quote:
Originally Posted by skisprinkle686 View Post
So I was able to get two videos this morning during warm up. The first video is from the top. The second is from just beside the drivers side shock. I still think it's more than a flexplate. Any ideas?

https://www.youtube.com/watch?v=6SXsEXRP-Ls

https://www.youtube.com/watch?v=RMHEWKxpxZQ
Your videos are listed as 'Private' and we can not watch them.
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post #7 of 14 Old 05-02-2014, 11:40 AM Thread Starter
skisprinkle686
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Sorry about that. Now you should be able to view them!

1999 WJ 4.0L V6 Limited
Rusty's 2.0" Lift
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post #8 of 14 Old 05-02-2014, 11:45 AM
harkinsc
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Quote:
Originally Posted by skisprinkle686 View Post
So I was able to get two videos this morning during warm up. The first video is from the top. The second is from just beside the drivers side shock. I still think it's more than a flexplate. Any ideas?

https://www.youtube.com/watch?v=6SXsEXRP-Ls

https://www.youtube.com/watch?v=RMHEWKxpxZQ
It definitely does not sound like a rod or piston. I'd start by having a look at the flexplate. It should be a pretty simple task on the 4.0L.
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post #9 of 14 Old 05-02-2014, 01:10 PM Thread Starter
skisprinkle686
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Quote:
Originally Posted by harkinsc View Post
It definitely does not sound like a rod or piston. I'd start by having a look at the flexplate. It should be a pretty simple task on the 4.0L.
What signs would you be looking for in a rod or piston?

1999 WJ 4.0L V6 Limited
Rusty's 2.0" Lift
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post #10 of 14 Old 05-02-2014, 01:53 PM
harkinsc
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Quote:
Originally Posted by skisprinkle686 View Post
What signs would you be looking for in a rod or piston?
For the rod knock, I'd be looking for bearing material and/or metal shavings in the oil. For the piston skirt, I'd be looking for large chunks of piston skirt in the oil. Dip stick is an okay way to check for shavings or bearing material. Dropping the oil pan and visually and physically inspecting the connection rods is your best bet for determining rod knock.

The first thing I would do is take off the torque converter cover plate and bellhousing brace to inspect your flexplate and associated bolts to the torque converter. If that looks okay I would do a compression test on all the cylinders. If that checks out okay I would drop the oil pan and inspect the connecting rods, cylinder walls, and underside of the pistons.
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post #11 of 14 Old 06-06-2014, 07:21 AM Thread Starter
skisprinkle686
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So now I have a new issue Jeep started making a ticking noise that would get louder as I accelerated. Then yesterday it also started doing it while idling. Was driving it home and heard a loud pop then the engine died. Had to have it towed to my local mechanic who is checking out today.

What do you guys think? Crankshaft? Piston? Timing chain?

1999 WJ 4.0L V6 Limited
Rusty's 2.0" Lift
Flowmaster 40
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post #12 of 14 Old 06-06-2014, 06:18 PM
KayCeeJeep
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Quote:
Originally Posted by skisprinkle686 View Post
So now I have a new issue Jeep started making a ticking noise that would get louder as I accelerated. Then yesterday it also started doing it while idling. Was driving it home and heard a loud pop then the engine died. Had to have it towed to my local mechanic who is checking out today.

What do you guys think? Crankshaft? Piston? Timing chain?
Ugh I'd guess piston skirt.

STOCK WJ WARRIOR
2004 4.0 Laredo Selec-Trac at 132k
General Grabber AT2's
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post #13 of 14 Old 06-10-2014, 07:05 AM Thread Starter
skisprinkle686
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Turns out there is no compression on cylinders 4-6. Was told the connecting rod on cylinder 5 is broke. Looks like it might be time to cut my losses....

1999 WJ 4.0L V6 Limited
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post #14 of 14 Old 12-14-2014, 10:05 AM
nyks02wj
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not to beat up a dead thread, but i have a 4.7 making a noise from the bell housing.. or about 2 weeks now after 2500rpm it goes away.. loudest at 2k.. question is if flexplate bolts backed off can i just retighten them or get new bolts.. also anyone know if i have eto drop the exhaust... i just put the engine into the jeep about 1 month ago.. issue just started arising last week or so.. an help out be greatly appreciated...
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