This knocking noise is really bad, isn't it?

M

MacGryphon

New Member
Joined
Jun 26, 2020
Messages
11
Location
GA
Started hearing a clunk/knock from my 2003 4.0. I was hoping it was steering suspension related, but immediately went home and found that it does it at idle too. :(

In trying to troubleshoot, I rev’d the engine slowly to about 3000, and I’m pretty sure I made it worse.

Here is a short video of the sound at idle. It is MUCH louder in person.

 
Damn, that's not good. Sounds like you've got some rod knock or valve train issues. Have you done a compression test?
 
I have not done a compression test. I’m pretty mechanically inclined, but have never done one before...is it difficult?
 
Not tough, check you tube and can rent the tool from advance auto or auto zone I think.
 
Get a stethoscope and see if you can figure out if it’s coming from the bottom or top. Sounds like a rod knock to me though.
 
Be sure to let us know what you find.

Unless that is the flywheel hitting the bell housing shroud or something weird... That really sounds rough.
 
Before you get too stressed, let the engine cool down and run it with the belt removed. If the sound goes away, you’ll know it not the engine. If it is the engine, eliminating the roar of the fan will help to isolate the source.
 
Doesn't sound like any rod knock or valve train issue I've ever heard before, almost like the exhaust manifold broke. BIg puff on the broken cylinder and then small puffs from the others. Hopefully it isn't too bad.
 
Update: I have not done the compression test yet, since most stores are closed today. I did take the belt off as suggested, and the noise is definitely still there. :(
I know sounds echo and bounce around in the engine compartment, but it definitely seems like the noise is more pronounced on the passenger side.
 
Alright, I ran through a dry compression test of all cylinders. I didn’t do a wet test yet because the numbers below isolated cylinder 5 as the problem.

1- 165
2- 170
3- 175
4- 175
5- 65 (yes, Sixty five)
6- 175

Do I still need to do a wet test? What comes next?
 
Top Bottom
Back