marklar134

so i just bought a 2001 grand cherokee with a 4.0. i just changed the oil, and now there is a knocking and it sounds like it might be bottom end. there was no metal in the oil or the pan (i resealed the pan the same day i changed the oil). anyone have any ideas? pretty sure its going to need a rebuild or a reman put into it but im hoping someone has some input that doesnt require putting a motor in this thing.

Nick-B

If it quiets down some when its warm then it is likely just piston slap. Common.
It could get more serious if a piston skirt breaks but the 4.0 will often run a long time with a bit of piston slap.

marklar134

well i work at a ford dealer and am going to bring it in on my day off and see if i can find out exactly what the issue is. ill probably be able to pull the engine and trans out and rebuild them here if they let me keep the jeep in the lot

MoparNJeep

Could be the flex plate knocking also.

marklar134

well sitting under the jeep while its running it sounds like its coming towards the front of the motor. itd be great if it was just the flex plate but i have a feeling its a bit more serious than that.

Jeepin'_Aint_EZ

Hopefully you get this movie reference....

marklar134

unfortunately i dont think a handfull of sawdust is gonna fix this one lol

Jeepin'_Aint_EZ

Thanks for playing along

I was actually thinking that maybe it had the sawdust in before and you just drained it all out

marklar134

well the oil was real dark but didnt see any metal, i also resealed the pan and there wasnt any metal (or sawdust) in it either, i think im just going to spring for a full rebuild kit for the engine and the trans

marklar134

ordered an engine and a trans rebuild kit.

Cleman Simpson

Is there any possibility that the pan re-seal got the crank to tapping on the pan? Like with a too thin gasket?

marklar134

theres a cradle-type plate (i dont know chrysler terminology) between the crank and the pan, and i used a mopar gasket from the jeep dealer next door and i felt the pan from front to back and i didnt feel any contact.

marklar134

found my knock, piston number 6. all the journals look good and cylinders dont have any gouges and you can still see crosshatching, gonna take some measurements today and hopefully start throwing it back together.

Fred/N0AZZ

Are you not going to rebuild it being it's that far apart, sure is a good time to do so if the rest of the Jeep is in good condition.

marklar134

i took it apart because im rebuilding it, im also overhauling the trans