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Unread 09-16-2014, 12:36 AM   #1
Registered User
2000 TJ Wrangler 
Join Date: Mar 2013
Location: Irvine, California
Posts: 3
2.4l piston problems

Hey guys, my Haynes manual doesn't provide any cylinder specs for the 2.4l engine so i figured i would ask you guys.

i have a 2000 TJ with a 2.4l engine. a few years ago the #4 piston broke a skirt. at the time i didn't have the tools to measure out the bore and all that so i just got an OEM piston and threw it in there. a few years later i lost compression in that cylinder so i took it out and found that the rings were shattered and the gaps were hammered out a bit. i knew its days were numbered but i didn't have the means to do anything else so i just put new rings in as a band aid until i could fix it for good. its been OK for a few months, but the other day i lost compression again. i just took it apart today and found that the meat between the gaps had busted off. i measured out the bore at the top middle and bottom with a bore gauge and calipers (i didn't have a micrometer) and got these results:

Parallel measurements
Top- 3.880"
Middle- 3.880"
Bottom- 3.878"

Perpendicular measurements
Top- 3.870"
Middle- 3.874"
Bottom- 3.877"

I measured several times to be sure and they were all approximately the same. my main question is what are the dimensions for the bore supposed to be, what is the piston size supposed to be, and what are the piston-to-bore gap tolerances? also, should i be worried about the bore being out of round and tapered or is is within acceptable limits? i can certainly measure them again to be sure, maybe my technique is a bit off. anyway thanks ahead of time for any help.

bigsherm2211 is offline   Reply With Quote Quick reply to this message
Unread 09-16-2014, 09:27 AM   #2
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1999 TJ Wrangler 
Join Date: Apr 2010
Location: Felton, Delaware
Posts: 3,049
98.45 to 98.48 mm (3.8759 to 3.8775 in)

Pulled from here but the blocks are the same 87-02... by the way you have a 2.5l engine

Not sure about the rest of your questions.

Sent from my Galaxy Note 2 using my thumb
wwch99tj is offline   Reply With Quote Quick reply to this message

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