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Q: Hemi top end started making 5loud noise.

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I have an 05 grand cherokee with 5.7 hemi. I took the heads off because I started getting a really loud almost knocking sound, which I thought was coming from the bottom end but it doesn't do it cold and when I reved the motor the noise gets faster as well. Used a stethoscope and found it was top end. The heads are at the machine shop being checked out now. My question is can a lifter make a noise like that? Should I change them regardless? If so is it possible to swap the MDS lifters for non MDS lifters like they put in the 3/4 ton hemi trucks?

My car has 224 miles.
My car has an automatic transmission.

A: Hello. To answer you first question, yes, d...

Hello. To answer you first question, yes, defective lifters can cause loud knocking noises to come from the cylinder heads. If any of the lifters get stuck or lack lubrication it may cause them to make a noise. The noise may be loud if the wear or play is caused as a result of the problem with the lifter. I would carefully examine the lifters, or have the shop examine them just to be sure that they are okay. As far as swapping your lifters for a different style, I would also consult the machine shop for advice, as they most likely will have specific diagrams and part numbers.

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