Piston,big end, main bearing measurements

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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Elmhousewillys
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Piston,big end, main bearing measurements

Post by Elmhousewillys » Tue May 04, 2021 11:15 am

Evening everyone

Does anyone know what the standard size measurement of pistons, big end bearing and main crankshaft bearings are on a post war engine for a willys jeep please ??
Just about to have an engine overhaul!!

Also looking to find out year of block, its stamped what looks like MC89199...any info appreciated....thanku

Regards Martin


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Re: Piston,big end, main bearing measurements

Post by '42 Peep's Motorpool » Tue May 04, 2021 3:04 pm

Hi,


Based on the serial number, you have a block originally installed in an M38.


You should verify the numbers in case there was a typo in my manual, but this is what I have handy for the postwar blocks:
L-134 Bore: 3.125" to 3.127" [source: Service Manual for Universal Jeeps]
Crankshaft main journal, standard: 2.3341" to 2.3331" [source: Service Manual for Universal Jeeps]
Crankshaft connecting rod journals: 1.9383" to 1.9375". [source: Service Manual for Universal Jeeps]

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dpcd67
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Re: Piston,big end, main bearing measurements

Post by dpcd67 » Tue May 04, 2021 5:13 pm

MC 89K engine is a very late M38 engine made probably in 1952. If you are working on any L134 you need the TMs associated with them, and as referenced above, the Jeep Universal civilian manual. You can't possibly work on an engine without the TMs. 9-1803A is the WW2 TM; I would tell you the M38 but it is upstairs and you can look it up.
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Elmhousewillys
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Re: Piston,big end, main bearing measurements

Post by Elmhousewillys » Wed May 05, 2021 12:28 am

Thanks for the information....just for reference, is there a site that gives info on engine serial numbers??

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dpcd67
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Re: Piston,big end, main bearing measurements

Post by dpcd67 » Wed May 05, 2021 5:58 am

Yes; Google Willys jeep engine numbers and you will get it.
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