Posted: Wed May 25, 2016 1:13 pm Post subject: M38 Engine
I have a couple of questions regarding the M38 Engines:
1) How can you tell if an engine actually belongs to an M38 other than the 24V stuff, what should be there?
2) How much do correct m38 engines cost in running but needing to be rebuilt condition? (I am sure availability will be an issue as well since there were not as many produced)
3) Can a CJ L-134 be converted to 24V and what kind of impact would this have on restored value, all things equal?
I am eyeing an M38 but it is 12V and I am not sure if it had a CJ L-134 engine swapped in or not.
thanks,
Jason _________________ Jason M38A1
Joined: May 30, 2014 Posts: 3447 Location: Texas Hill Country
Posted: Wed May 25, 2016 6:31 pm Post subject:
One other identifying trait of a military block or head is the
water pump bypass hose. It's a 3/4" diameter hose in an L
shape coming out of the top of the water pump and going into
the front of the head. Only the military head had this hose
installed.
Certainly there is a greater value for an M38 with an original
engine. It all depends on what you plan for the jeep.
A factory correct, numbers matching (good luck with that by the
way) M38 in as new condition is at the top of the value chain.
From there, the next level is Motor Pool, which means all
equipment installed had to be a replacement option by the
motor pool guys at whatever moment in time you are picking
for your jeep.
The last group is a daily driver. With this one all bets are off,
and folks build and maintain them up to as close to military
service as they want, but don't get wrapped up in whether
it has the two plug Bendix light switch or first aid kit.
With motor pool, it has to be 24 volt, and it has to have an M38
engine. Replacement motors were still military blocks.
There are plenty of folks driving M38's that are daily drivers,
that are very close to motor pool class, but are 12 volts,
have civvy engines, and other non-military items.
Anyone here would encourage you to get it running, and
of course would prefer it to be a military restoration,
but in the end saving a 65 year old vehicle from oblivion
is the main goal.
There are lots of folks here that will be happy to help you
with any of the above options above.
How can you prove numbers matching on it? Does the transmission and transfer case have the same serial number stamped on them? _________________ Jason M38A1
Joined: May 30, 2014 Posts: 3447 Location: Texas Hill Country
Posted: Wed May 25, 2016 8:10 pm Post subject:
There are quite a few posts here regarding numbers in the M38's.
The short version is when the M38's were assembled at the
factory the dash plate and the patent plate on the tub matched.
The engines were assembled and stacked in a spot, and when
a vehicle came along the line the guys just grabbed a motor.
As I understand it there is no historical correlation to the dash
plate and patent plate on an M38 and the engine serial number.
And when an engine needed to be rebuilt sometimes the
number was machined off when they decked the block.
I have an engine that was rebuilt at Pueblo in 1955. No serial
number and the mounting plate and bell housing are from a
later M38. So the Army put in what was available not worrying
about the restoration police somewhere down the line.
1) How can you tell if an engine actually belongs to an M38 other than the 24V stuff, what should be there?
2) How much do correct m38 engines cost in running but needing to be rebuilt condition? (I am sure availability will be an issue as well since there were not as many produced)
3) Can a CJ L-134 be converted to 24V and what kind of impact would this have on restored value, all things equal?
1-The only way is the serial number. An M38 engine delivered in a factory M38 will have the serial MCXXXXX or MCXXXXXX. The six digit numbers showed up at the very end of production in Apr/May 1952. Engine serials do not match body serials on Willys jeeps built after WWII. A brand new factory replacement engine (these were purchased under the same contracts as the jeeps by the thousands) have the serials RMCXXXXX and RMCXXXXXX. Again the 6 digit numbers appeared in Apr/May 1952. Also keep in mind that MC prefixed serial engines also were shipped in PE95 stationary power plants.
Quote:
2) How much do correct m38 engines cost in running but needing to be rebuilt condition? (I am sure availability will be an issue as well since there were not as many produced)
2-You will find prices all over the bases. I have purchased MC prefixed blocks from $50 to $200 as cores.
Quote:
3) Can a CJ L-134 be converted to 24V and what kind of impact would this have on restored value, all things equal?
I would not say convert to describe what is done to make any L134 suitable for a stock M38. The accessories (starter, generator, carburetor, distributor and fuel pump do not an M38 engine make. Nor due 24V senders, bypass hoses or heads with a 1/4" pipe hole tapped in the front.
The 641087 or 804380 block castings become M38 engines only when they have the MCXXXXX or MCXXXXXX or RMCXXXXX or RMCXXXXXX serial stamped on the flat above the water pump. A JXXXXX or a 3JXXXXX or TXXXXX or CJVXXXXX or UXXXXX serial number block is not an M38 block no matter what dressing you adorn it with. Earlier casting numbers and later casting numbers were not used for M38 production period.
This casting 641087 late with the reinforced rear flanges was used in a test run in Jan 52 on 102 M38's (SN MC51887 thru 51988) then appeared to stay in Feb 52 at SN MC53262. From Sep 1950 thru Feb 52 three earlier versions of this 641087 block were used. Then in Jun 1952 the 4th version of the 641087 became what it was suppose to be in the first place, a new casting number 804380. The blueprint that created the series 4 641087 block said right on the blueprint that the casting number was to be changed as well to 804380.
Back to your question. How do you convert or as I would say build your civvy or unidentified serial number 641087 or 804380 block as an M38 block. You use the parts list items specified for the M38. To what degree of accuracy depends on your goal, planned use or restoration quality.
So you start with nothing more than a 641087 short block assembly. No head and no accessories. You will need to know if you have a series 1, 2, 3, or 4 641087 casting to decide what bell housing setup and starter is going to work. You will need to ascertain which front mount plate you have or need. You should use one with a hole in the left side for the dual type fuel pump, a left mount ear facing forward and a large mount hole for the generator. You will need the accessories themselves and attaching parts/hardware. Decide on early, late or no fording plumbing ahead of time. I am sure I overlooked something but the point is you have a difficult task ahead of you that will not be overly difficult if you pre-arm yourself with the necessary data easily found in the manuals available on our web site and those civilian parts list that match the year model jeep engine you are using. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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