willysmjeeps.com

Last night when I was doing some tear down, I noticed a set of stamped
numbers on the left side of the engine block. They are 90348 and
seemed to be on an area specifically for this. These numbers are
different from my jeeps serial number on the data plate. Do the two numbers correlate together or is this a serial number specific to just the
engine. I’ll try and get a photo up. Thanks for any information.

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Someone else will give more details soon... so I'll just fill in what I know for now.

Orientation for a F134 (my terminology as I personally find 'left side' to depend on where you looking at it from):

"Front" is where the radiator is.
"Driver side" is where the exhaust is.
"Passenger side" is where the starter is.

There is a raised cast number on the passenger side down low which is the engine block casting number - there are a small handful of different casting numbers for the F134, so most M38A1 will share this number.

On the front, there would originally have been a stamped number on a flat machined spot on the block above the water pump - it's just at the mating line with the head. This is the engine serial number and is not connected or related to the body serial number. There is a prefix for this - MD would originally have been an M38A1 engine, RMD would have originally been a replacement engine made at Willys for M38A1, other prefixes for other vehicles. After the serial number in some cases there would be a suffix if bearings or cylinders were other than nominal size. Later in life when a block is machined to return the interface between head and block back to flat, it's not uncommon for this serial number to get machined off.

If an engine is rebuilt by the military they would (often? always?) attach a rebuild tag to it - I'm not sure if there is a standard location for this, but I believe it's an aluminum plate with stamped info on it that is attached to the block.

Ivoryring,
Thank you for the reply. I guess I could have been a little more specific on the location of the serial number. It is located on the exhaust side of the engine towards the bottom right if you are looking at it from that side. It is located on a machined flat spot that seems to be specifically for this.

That spot was for any future rebuild data plates and in some cases the ID plate for power units, generators and welders..


This is an L134 sowing the exhaust side raised flat for the Rebuild Tags

As I said in my email to you, you should post a photo of this number.

So, here I am after this last year of craziness. I’m finally able to get back to work on the 52’ A1. This photo shows the spot on the block where a number is stamped. I am aware this could be an arbitrary number from over the years. However, I have not been able to locate an F134 with this raised area casted in it and I’ve also noticed a few other characteristics I have not seen on other blocks. I’ve circled these in yellow.

https://photos.google.com/photo/AF1QipP ... ANOdxgGWPB

[From Management: Link does not work.]

[From Management: normally using these brackets, , for your photo links will load that photo here in your post but the link must be freely accessible not requiring a sign in or pass word at the linked site. Often this is termed as "public link".

Just go to my photo album. Second album in Member's Albums and go to my F134 sub-album and the M38A1, M170, M38A1 CDN Survey guide Sub-Album. I have every number labeled somewhere in those photos. Don't overlook my L-134 Sub-Album, except fro the head the rest of the block numbering is virtually the same as the F134.