M38 Crankshaft Pulley - Timing Marks

RonD2

I bought this nice and solid take-off M38 pulley to replace the CJ pulley that came on my spare RMC engine.
After getting it cleaned up and primed, I notice these timing marks.
The manual says the timing hole mark is located for 5-degrees BTDC, and I expected to find the notch cut in the outer rim to be the same.
Obviously not.
Then I was thinking maybe one or the other might be a TDC mark, but not now as they appear to be more than 5-degrees apart.

I searched old posts with no joy, but might've missed it.

Anybody seen this before?
What do I have?
Mis-marked government reject that made it into the market?

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_________________
Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51

“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari

Kendall · Posted: Mon Oct 10, 2022 3:37 pm Post subject:

The notches look to be the work of Bubba.
_________________
1951 M38
1952 M38
1952 M38A1
1942 Dodge WC-55
1951 M100 trailer
1942 Ben Hur trailer

RonD2 · Posted: Mon Oct 10, 2022 4:15 pm Post subject:

I thought it looked well done but I suppose that's possible.
I don't have another to compare it to.

The pulley on my M38 is a repop (that's going to be replaced soon). It has a notch but no hole. So no joy comparing the two.
CORRECTION: this pulley does have a hole and notch, and they line up correctly with each other.

Even if it were true (Bubba work), that doesn't explain where's the proper notch that's supposed to align with the hole?
I had this pulley down to bare metal before priming it and there's no evidence of any other notch anywhere.

Did the factory drill the hole and the Army motor-pool mechanics cut the notch on them?

Thanks Kendall !
_________________
Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51

“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari

Mike_B · Posted: Mon Oct 10, 2022 6:40 pm Post subject:

When you line the crank Key Slots up on both pully's do any of the timing marks line up with each other?

Mike B Smile

_________________
Mike B
1953 M38A1 Brush Truck
1952 M38
1951 M100 Trailer

RonD2 · Posted: Mon Oct 10, 2022 7:13 pm Post subject:

Hi Mike, and thanks. Good idea.
With the woodruff key slots lined up on both, the notch's line up exactly.

The hole in the primered pulley is located in the wrong place.

See my corrected post directly above this one.

I suppose I can fill it with a dab of JBWeld and drill one in the right place.
Maybe before I do that I'll get my hands on another NOS or take-off pulley just to compare.
I recognize it's a leap of faith that the repop pulley I have is "more correct" than the take-off pulley I have.
_________________
Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51

“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari

CoastieReid · Posted: Tue Oct 11, 2022 4:15 am Post subject:

My pully has a notch filed on. And my front cover has a raised rib - no pointer, and I will verify today if mine has a hole- I don't remember seeing one.
The engine only had 30k miles on it.

On edit, I went through my photo albums and found the fresh rebuilt engine photo i took of the pulley.

There is a groove and a mark.

no hole drilled in mine.

_________________
April
i have a build thread on Youtube. just type in CoastieReid in the search.
MC 66792 5/52
Hood # 20942580
L134 # MC 91518

M100 trailer #01279054

RonD2 · Posted: Tue Oct 11, 2022 8:09 am Post subject:

Thanks April.
The hole on mine is drilled on the inside of the mounted pulley, the side that faces up against the timing cover.
I have no clue why the Army put it there because it's difficult to see when mounted.
Unless maybe it's only purpose was to locate the notch for a field mechanic to cut.
_________________
Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51

“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari

Mike_B · Posted: Tue Oct 11, 2022 6:26 pm Post subject:

My pulley has the hole and a V notch, both lined up together. Until now I never gave the hole a second look...I just assumed it was there as part of the manufacturing process...learned something new!

I'll email you a picture.

Mike B Smile

_________________
Mike B
1953 M38A1 Brush Truck
1952 M38
1951 M100 Trailer

wesk · Posted: Wed Oct 12, 2022 12:11 am Post subject:

Several years ago one of our members got a hold of a Factory new NOS RMC engine still in the crate and posted photos of this new engine:

This is a closeup of his of the timing marks:

The composite illustration below should help fill the gaps so to speak:

_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

rgmutchler · Posted: Wed Oct 12, 2022 7:43 am Post subject:

As to timing marks. I don't remember the serial # breaks but the early MC engines at least through about 13122 did not have any timing marks on the pulley or the timing chain cover. The only mark for timing it were on the fly wheel and bell housing near the starter. I had to add the bolt on timing indicator from a 134f and then find DTC and file a mark on the pulley.
_________________
R G Mutchler
M274A5
M-38 MC13312
http://willysmjeeps.com/v2/modules.php?set_albumName=rgmutchler&op=modload&name=gallery&file=index&include=view_album.php

wesk · Posted: Wed Oct 12, 2022 9:57 am Post subject:

Correct. I haven't been able to locate the paperwork yet to support the transition from the flywheel to front pulley timing marks. Army motor pools were doing it on their own fairly early and I believe there was mention of this issue in the Army's Vehicle Service Magazine called PS Magazine way back as well.
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

RonD2 · Posted: Wed Oct 12, 2022 11:56 am Post subject:

The flip (front) side of my pulley looks like all the others.
The "spoke" pattern is the front side of the pulley (when mounted on the engine), and the side with the timing hole is the back side up against the timing cover.
The timing hole is hard to see when the pulley is mounted on the crankshaft. Perhaps that's why the notch got put on later.
I can post a photo of the front of mine if necessary.

While I appreciate the comments, I'm not sure where this post is going?
I'm just trying to find a possible explanation for two timing marks (the 1/8th-inch hole and the notch) not being aligned on this particular pulley I bought (advertised as M38 take-off, but I have no way to prove that).

I'm still thinking it's some kind of defect because all other indications so far tell me the 2 marks should be aligned and located for 5-degrees BTDC.
If it is a defect, I see no way to tell if the factory did it or an Army mechanic did it, or both.
Especially since it looks like the hole is located wrong on mine and the notch is in the right place.
And it wouldn't be the first time that defective (reject) government parts were sold into the civilian market.

Seeing the original Willys engineering drawing for the pulley would be great!

Incidentally, this TB and MWO (both issued after M38 production ended) are pertinent:
TB ORD 547, 18 DEC 1953, 1/4-ton, 4x4, utility trucks M38 and M38A1, Prevention of crankshaft pulley failures
MWO ORD G1-W54, 15 SEP 1954, ¼ ton 4x4 utility truck M38 & M38A1, Installation of new engine timing indicator
_________________
Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51

“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari

RICKG · Member Joined: Aug 31, 2010 Posts: 1740 Location: SO IDAHO

Ron I've got 2 clean takeoffs on the shelf. you've got me curious. i'll take a look at them.
_________________
keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

RICKG · Member Joined: Aug 31, 2010 Posts: 1740 Location: SO IDAHO

pulley1, black came off a RMC L134 core, notch only.
pulley2, green came off a MC L134 core, hole only.

ive got a foto to post but its taking too long.
_________________
keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

RonD2 · Posted: Wed Oct 12, 2022 7:24 pm Post subject:

Interesting!
I hope you can post the photo.
(I've also noticed it takes a lot longer lately).

Thanks Muley!
_________________
Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51

“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari


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