I got a knock when the foot is OFF the gas pedal. It’s definitely coming from the engine. 2.5L 2001 tj with 187k miles. The knock calms down a little bit when warmed up. Any ideas?
Knocking when foot off the throttle
- Thread starter Roxanne01TJ
- Start date
Anything you think I could try? I put thicker 10w30 in it. Did an oil additive. And now my friend is recommending 15w 40. Before I do anything I just want to figure out what kind of knocking it is
You could try adding some Marvel Mystery Oil to it. I’ve heard that can quiet the lifters down. It’s an additive.
Could it be the downstairs neighbors complaining about the noise again?
When I lived in town they would start knocking and banging everytime I cranked up the Metallica!
When I lived in town they would start knocking and banging everytime I cranked up the Metallica!
Well I rebuilt the engine about 500 miles ago, and there was some scoring on the inside of cylinder 3. Everything else seemed fine. Put it back together and the same knock came about.
If you left the scoring in a cylinder that could rather quickly cause ring problems. Or it could last for 200,000mi. The machine work is something that can't be neglected. Its normally the reason you are inside the engine in the first place. That and properly fitting bearings.
You might as well plan on pulling the motor again. 500 miles after rebuild I’m guessing someone got something wrong. You might get lucky and be able to fix it before it self destructs if you stop running it.
I didn’t have the money or the time, and it’s my daily driver so we basically just threw it back together, and put it back in.
Yeah, I might just go for a reman. Hopefully I’ll have enough time and money to get one from Jegs and prepare for a weekend swap
Have you considered piston slap? I know the 2.5 was known for that in the YJs.. not sure if it carried over to the 2.5 in the TJ....
When you say rebuilt the motor, did you install new rod bearings, main bearings and gauge for clearance?
The scoring could be a from a broken ring. Were the rings replaced? Just for clarification.
The noise sounds more bottom end when you say knocking.
A good way to hear what's going on and narrow it down is to use a long steel rod like an 3/8 or 1/2" extension. Place one end on the motor away from rotating part and the other end in a closed fist up to your ear. You'll hear all kinds of different sounds but you can find it's location as you try different spots. Very effective in hearing noisy roller bearings.
The scoring could be a from a broken ring. Were the rings replaced? Just for clarification.
The noise sounds more bottom end when you say knocking.
A good way to hear what's going on and narrow it down is to use a long steel rod like an 3/8 or 1/2" extension. Place one end on the motor away from rotating part and the other end in a closed fist up to your ear. You'll hear all kinds of different sounds but you can find it's location as you try different spots. Very effective in hearing noisy roller bearings.
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When I say I rebuilt it, I literally just threw all the stuff back together. The original plan was to buy a certified used engine, and just pop that one in and go. But we ran into some complications. So we put this thing back together, threw it in and rolled with it. Put about 1000 miles on it since then and no problems except for that knocking. It hasn’t gotten any louder. I just know that knocking isn’t gonna hold up forever. And it does sound bottom end, but when I open the good it sounds too end. I’ll take a video when I get the chance.
Yeah I have, and I wouldn’t be surprised if it was. These things practically came stock with piston slap. But piston slap goes away after warming up. This one doesnt.
A video would be great!
You might have a hydraulic lifter that's not working.
Two things to check:
Do a compression check and write down each cylinders pressure reading (e.g. 150psi)
Pull the valve cover off and check for proper rocker arm clearance on intake & exhaust valves. If it's a lifter you'll know pretty quick.
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