MC Engine: Did I actually find one??

[Naugha]

For some time I have been looking locally for a ‘real’ M38 engine, something with a casting number and MCxxxx serial number that would indicate it had once been under the hood of a M38. On line I mostly found ‘generic’ L-134’s. There are a few suppliers that have MCxxxx blocks or ready to go engines but prices are high for these rare birds, shipping is another expense and you don’t get to see the thing until it arrives. (Things you guys all know.)

Just when I thought I would use the CJ2A engine that came with the jeep, an engine popped up about an hour south of me that looked good.

Let’s see if my study of this engine ID stuff has worked. The last owner converted to 12v but I have the 24v components (untested). There are no obvious cracks on the outside but I have not pulled the head. The block serial number markings are very faint with the beginning ‘M’ almost gone. If you click on the pics I think you get a closer view.

Anyway ..... is this a ‘for sure’ MCxxxx , M38 engine block?
(The following link shows (should show) the entire set of pics for this thread including any new additions.)

https://photos.app.goo.gl/nNNfbxXdv8sxdWhE6

It is always nice to see what we are all discussing! Wes K Site Management

[Mike_B]

I'll let the experts weigh in for a positive ID, but to me it looks pretty good, dual pulley on the crank and correct front motor mount plate. My RMC engine has a very faint "M" also when compared to the rest of the numbers/letters...

Mike B

[jake138]

Not a professional, but I believe you have a January 1952 through June 1952 MC block.

http://willysmjeeps.com/v2/modules.php? ... block+date

No freeze plug in the back of the block, thicker flange at Bell housing with additional 5/16" bolt holes are clearly shown on the left side of the block in one of your photos. Based on Wes' information in the post linked above, this block could have been installed originally in a CJ3a or an M38.

The head on this engine has the front coolant port, leading me to believe it could be period correct to that block, but you will need the head casting number on top to confirm.

http://ww2jeeps.com/htm/heads.htm

The website above has some great pictures to help show you where that head casting number is hiding underneath that bracket.

As Mike_b mentioned, it also has the MC-correct front engine mount plate with the rear-facing passenger side motor mount tab and the forward-facing driver side motor mount tab.

If the serial number on the block deck face is real, and by my own personal approximations based on Wes' M38 serial number data base, this motor could have been installed in a March or April 1952 DOD M38. Anyone else please feel free to let me know if and why I'm wrong.

Looks like a nice find.

[Naugha]

The previous owner, a very solid fellow, explained that the engine came from his father’s M38 purchased around 1970. The M38 engine was replaced with a more powerful engine. The original M38 jeep is still on the road in the NC mountains. Amazing that there are still some of these MCxxxx engines out there ..... of course much must be done to refurbish such finds.

[wesk]

Eng does look like a late stage 3 641087 casting (or I should say a late 804380 casting which was among 100's that left willy Jan thru Jun 1952 with the wrong casting number 641087) Problem is it seems to be bolted to the late bell housing adapter plate but the bell housing does not have the late 6 screw inspection plate. It has the early bell on it.

Engine serials are not much help ID'g when they left Willys. The machining date stamped in the lower face of the block near the rear main is a better DOM estimate. The engines were stacked in a storage room near the assembly line and were pulled in no particular order at the production line. In fact many were shipped from that storage area to suppliers of compressors and generators for use as military industrial power plants with those MCXXXXX serials as well. Procurement contracts that requested spare engines also recieved them from both MCXXXXX and RMCXXXXX stocks.

[Naugha]

Engine serials are not much help ID'g when they left Willys. The machining date stamped in the lower face of the block near the rear main is a better DOM estimate. The engines were stacked in a storage room near the assembly line and were pulled in no particular order at the production line. In fact many were shipped from that storage area to suppliers of compressors and generators for use as military industrial power plants with those MCXXXXX serials as well. Procurement contracts that requested spare engines also recieved them from both MCXXXXX and RMCXXXXX stocks.

I will get more pics as the block gets cleaned up. The previous owner believes his father purchased the jeep from a college that had been using it before around 1970. He says a frame up restoration was done on the jeep (which is still used by family members in NC) but the engine was underpowered for their needs and was replaced. Maybe I should try to find out if that M38 still has its dash & wheel well numbers.

[wesk]

It is extremely rare for an M38 to survive 20 years without an engine replacement while it was in the military. For it to survive with it's original engine 70 years would be a phenomenal event. Even today there is no way to establish the originality of an engine to a M38 within several thousand serials. You have a period correct engine for your jeep now and the jeep it came from is no longer a player. Now it's time to concentrate on making your MC engine a truly original looking MC engine. It's time to look for a correct mechanical oil filter, a correct water pump, distributor and bell housing. Good luck with your new project.

[Roughneck]

It is extremely rare for an M38 to survive 20 years without an engine replacement while it was in the military. For it to survive with it's original engine 70 years would be a phenomenal event. Even today there is no way to establish the originality of an engine to a M38 within several thousand serials. You have a period correct engine for your jeep now and the jeep it came from is no longer a player. Now it's time to concentrate on making your MC engine a truly original looking MC engine. It's time to look for a correct mechanical oil filter, a correct water pump, distributor and bell housing. Good luck with your new project.

wes when i found my m38 in CT it was sitting outside since 73 but its never been swapped out and the data plates are intact and complete the speedo has less than 20k and the engine has the mc stamping if you would like my numbers id be happy to provide them

[wesk]

One could not confirm a 1951 M38 engine as original in 1955 because there was no established correlation between the chassis & the engine serials starting on the assembly line. The absolute only way to establish an MC engine as original to the M38 was to have taken delivery of the jeep brand new from Willys and recorded the engine serial along with the chassis/body serial. I have been operating Mjeeps and my old Yahoo m38/M38A1 jeeps groups since 1996. My experience indicates there is no way to confirm an MC engine original to a chassis other than as I stated above. WWII jeeps were the last to leave Willys with engine serials that matched their chassis serials. The best we can do today is guestimate the falling of MC engine serials with the production flow of chassis serials.

[45auto]

Naugha,
Of interest, I have engine 83861 in my database, just 8 units before your engine and its an RMC engine. So within the 8 unit spread, the short run of RMC engines ended and MC engines started back up. This is as close as I have come to determining an ending RMC run or MC start. Thanks for sharing your MC engine find!!

If you have the oil pump off, look for a date code. It will look something like:

3 - 28 D Which by comparing to other engines, would be March 28th 1952. If you do find a date code, please pass it along.

[dpcd67]

Even WW2 Jeeps from Willys did not have matching engines; they are off by many thousands. Only Ford numbered the frames to match the engines,
The best way is to look on top of the water pump boss and see the serial number; MC or RMC is what matters. My M38 has RMC56789. An RMC engine is fine with me

[wesk]

RMCXXXXX were Brand New Production spare M38 engines. The RMC does not stand for Reconditioned. The RMC translates to Replacement Military Model C. The spare engines listed on procurement contracts for M38's were RMCXXXXX serials.

[Naugha]

Right now the engine bolts are soaking in PB-Blaster. I will add more pics to the above group as I take a closer look on the inside. I am moving along on the body and also trying to identify the proper engine peripherals. My pile of parts contains pieces from three engines.....so, back to looking at the albums.

BTW.... if there are any Zoology/Botany/Taxonomy nerds out there with time on their hands ..... you know what we need.......

[ / L-134] Go to Section Three.... Item discriptinon 7..... Pic #1-4.

[dpcd67]

Hope you didn't think that I think that RMC engines are "reconditioned". Well aware that they were newly procured spares.

[wesk]

I did before you changed this "An ReC engine is fine with me" to this:

An RMC engine is fine with me