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brownjeff, ASE Certified Technician
Category: Jeep
Satisfied Customers: 13886
Experience:  17 years experience, ASE certified, dealership certified, Service Manager for 15 years,
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1999 Jeep: a loud knock in the motor

Resolved Question:

My 1999 Jeep has a loud knock in the motor. It pretty much started out of nowhere and is now a constant knock. It's not blue smoking and doesn't seem to be burning any oil. Any suggestions?
Submitted: 6 years ago.
Category: Jeep
Expert:  brownjeff replied 6 years ago.

Does the noise increase with rpm of the engine?


Is the noise from the top or bottom of the engine?

Customer: replied 6 years ago.

Honestly I can't tell if it is from the top or the bottom. What's the difference? Does the fact that there is no blue smoke make a difference?


Expert:  brownjeff replied 6 years ago.

The fact there is no smoke doesn't narrow it down.....


Does it change with engine rpm?


When is it the loudest? On acceleration or deceleration?

Customer: replied 6 years ago.

I believe it gets louder during acceleration. . . but it's a constant knock.


Expert:  brownjeff replied 6 years ago.
Have you tried to cancel out a cylinder to see if the noise would change?
Customer: replied 6 years ago.

No, I'm a female and my ex husband was a mechanic . . I'm familiar with terminology but that's it.


Does it sound like a major repair to you?

Expert:  brownjeff replied 6 years ago.
Either way it will be some what of a repair. You either have a lifter issue or a rod bearing. If canceling out a cylinder changes the noise it will be a rod bearing if it doesn't change the noise a lifter. either job is going to cost between $600.00 and $900.00 dollars
Customer: replied 6 years ago.

I know this is prob a silly question, but 600-900 dealership rates?


Is the majority of that cost labor?


How much do you think parts would cost?

Expert:  brownjeff replied 6 years ago.

Here is the parts:


Bearings : $132.00

Lifters: $180.00


Yes I gave you dealer pricing so you could get it done cheaper from a repair shop.

Customer: replied 6 years ago.

Unfortunately, I feel like because I'm a woman and look younger I may get taken advantage of. I did describe the problem to someone that I know who used to work in the auto field and he said it sounded like maybe it could be a lifter and someone else agreed. Someone else (not that saavy in auto repair) said bearing, and then a local mechanic said Jasper motor - no other options???


It has a 4' lift and 33' tires- could the strain on the motor cause this issue?


I'm taking it to someone who does mechanic repair on the side and hopefully they can resolve the issue. In the meantime, I was trying to do a little research myself.

Expert:  brownjeff replied 6 years ago.
Yes the lift and bigger tires will make the engine work harder. There really are no other repair options other than what was mentioned.
Customer: replied 6 years ago.
Expert:  brownjeff replied 6 years ago.

Your welcome....


Please click ACCEPT if we are done.





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