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knock sound

Z

Zweibrucken

Basic User
City
Papillion
State
Ne
Picked up my Scrambler today drove 160 miles then got off the interstate and had a bad knock. The PO had the #6 rod bearing replaced a year ago and has only driven 400 miles in the last year. I thought is spun the bearing and was only 1/2 way home. I drove the other 2 and a half hours at about 55 mph and it survived. I only dealt with a rod bearing 14 years ago so i'm pretty rusty on this. First gear and second gear i get the knock under load in 3-5th is seems to diminish. Can I be wrong on the sound?
 
Zweibrucken said:
Picked up my Scrambler today drove 160 miles then got off the interstate and had a bad knock. The PO had the #6 rod bearing replaced a year ago and has only driven 400 miles in the last year. I thought is spun the bearing and was only 1/2 way home. I drove the other 2 and a half hours at about 55 mph and it survived. I only dealt with a rod bearing 14 years ago so i'm pretty rusty on this. First gear and second gear i get the knock under load in 3-5th is seems to diminish. Can I be wrong on the sound?
Click to expand...

It all depends on where the sound is coming from... is it the engine, trans, or trans case.
Also... he ripped apart the engine and replaced 1 bearing? That part is a bit confusing, more details needed.

cb
 
A rod knock is usually unmistakable. It's not a tap. It sounds like a hammer hitting metal. If it's a rod knock it will need completely rebuilt. You can replace just the bearing but it will come back soon just like it did to you.

A rod knock will be present at all engine rpm. It will be louder when under load and higher rpm but always present.

Pinging due to incorrect timing will come on under load but probably go away at idle. It sounds more like rocker noise tho IMO.
 
Ok I agree not a rod. My YJ had a lifter tick and it's no tick. So if it's the rocker does the top end need to be rebuilt? I'd like to get some time from the motor before replacing it. After all it survived 5 hours in the interstate, I will admit I was getting insurance going down the road. I will say first hand between the wind noise, heat (windows up), and trying to read the VIN hooking up I29 was not fun. Needed that insurance incase it had to get a tow...lol
 
Pull the valve cover and make sure all the lifter rods are attached and straight. Also that the rockers are tight.
 
LetchcoreCJ7 said:
Pull the valve cover and make sure all the lifter rods are attached and straight. Also that the rockers are tight.
Click to expand...


...and that the rocker bridges are straight (rocker centered on valve, a bent bridge will pull the rocker off center).
 
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