willysmjeeps.com

Just acquired a 1953 M38A1. Was told the owner did very little changes but am suspicious of engine. Serial # is 42882 (3/53), Ordinance was Marine Corp and body matches the dash plates. Engine number, top of block, is 648830.
Fuel tank was single type, replaced with dual gas/air. Carb is Carter 938SD, rebuilding it now (this carb does not have the right angle throat - is straight up and air cleaner attaches to it. Also have a valve at rear of engine near the temp sensor - looks like a heater valve but cannot find in manuals (came with original manuals). Is this a military engine or civ - what is this valve? I have been assigned a photo album but not had the time to manage it yet.

Appreciate all the valuable info you guys have put here in the forum - you have no idea how helpful it is to a new guy like me - thanks again!

Engine runs if I pour gas down the carb, rebuilding tank and carb, pump and all lines replaced. Anybody needs some varnish?

Thanks on the varnish offer. I have plenty!

Look down on the right or left side of the block. There may be a
plate riveted to the block indicating it was rebuilt by the military.

Yes that t fitting with hose connections? Is probably a civvy water heater
install. More info and more pics!

Welcome to the green disease ward!

no plate for rebuild - I had read about this and looked...unless I don't know what I am looking for.....

I see the dash spot for the crankcase ventilation but no vent on the engine...that I can see.

Lee, Get into the manuals you don't have by downloading them all free in PDF format right here on our downloads page. There is absolutely no excuse for not using the manuals here.

Also don't overlook the wealth of info available in our members photo albums. Mine is the second album. I have over a 1000 technical photos and illustrations in there divided among sub-albums titled by system or system groups.

http://www.willysmjeeps.com/v2/modules. ... _album.php

Once into my album the very 2nd sub-album is all about the F134 engine.


This is a right side view. This is where you ID the engine's casting number. This casting number is on the early M38A1 engines.


This is a left side view.


This is the later M38A1 casting

In my sub-album on ID'g your M38A1
http://www.willysmjeeps.com/v2/modules. ... _album.php



F134's installed at the Willys/Kaiser factory in a M38A1 will have a serial number with an MD prefix. The factory supplied the Army with extra factory new engines for spares. These have an RMD prefix. These prefixes are often stamped much lighter than the main serial number so look hard for it.

The only things that make a civilian F134 differ from a military F134 are the accessories items bolted to the basic engine and the serial prefix stamped above the water pump.

Your F134 should still have a prefix ahead of the serial you gave us.

Your carb is a civvy carb. The heater return valve is a civvy item.

Right side of engine # is: 646228-L-W 10ANI OR-N2
Top plate by water pump has no numbers as far as I can see.

Cannot see left side yet - will require much cleaning!

Hi Lee,
The serial on the flat behind the water pump is stamped in very lightly.
Don't use abrasives if you can help it.

There is also the chance the serial in that spot was obscured if the engine
was rebuilt and the block decked.

Well at least now you have a narrowed field of host choices. That engine was only used from 1950 thru about very early 53 in the Willys pickup, jeepster and the M38A1.

The safe way to check for lightly stamped or etch numbers is to lift off the paint easily with some DOT 3 brake fluid. Let it soak for a couple of hours and wipe it off.

Wes,
Is there a source for the block serial numbers for those three vehicles?

There are no production records of Willys engines by serial number to chassis model number disposition. The serials were consecutive on the engines and the prefix was stamped when the basic engine was pulled from stock for a specific chassis model. That little prefix is all you get.