Pulley Issues - Water Pump, Alt & Crank Shaft

1950 - 1968, M38, M38A1, M170, modifications, sugestions, and ideas, official MWO's and unofficial field mods.
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Gary 1952M38A1
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Pulley Issues - Water Pump, Alt & Crank Shaft

Post by Gary 1952M38A1 » Mon Nov 06, 2017 10:54 am

m38a1 water pump 2.jpg
m38a1 water pump 2.jpg (25.8 KiB) Viewed 7283 times
m38a1 water pump 1.jpg
m38a1 water pump 1.jpg (25.93 KiB) Viewed 7283 times
I am attempting to use both belts on my 52 M38A1 to drive the water pump and alternator, previously only used one belt. The new water pump I purchased (Omix Ada) the v-grooves are centered at 1/2" between. The crank pulley is 5/8" C to C, my civilian alternator (12V Delco) is more in line with the Omix Ada water pump pulley. Is there a crank pulley that can be used for the engine that will match the water pump and alternator center to center or am I stuck using one belt? I think I could pull the original water pump pulley off and use that with the new pump but that would be another $50 bill to get the pulley puller and I am not sure if it will fit the new water pump. The other option for the alternator is purchase another pulley that is more in line with the crank pulley. Somebody has got to have encountered this before.
Thanks


Gary 1952M38A1
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Re: Pulley Issues - Water Pump, Alt & Crank Shaft

Post by Gary 1952M38A1 » Tue Nov 07, 2017 10:54 am

Update, I was able to purchase a NOS water pump on flea bay with the original pully so it will line up correctly. Does anyone know why the aftermarket ones are manufactured this way?

zoob
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Re: Pulley Issues - Water Pump, Alt & Crank Shaft

Post by zoob » Fri Nov 10, 2017 12:23 pm

Most likely because they are made in a third world country where labor is cheap. Easier to machine the pulley from one lump of metal than make dies and press the parts. My 2 cents worth.

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Re: Pulley Issues - Water Pump, Alt & Crank Shaft

Post by Joe Gopan » Fri Nov 10, 2017 2:13 pm

Pump on the left has the pulley pressed on too far. Pulley hub should be flush with shaft. As far as fitting an alternator, it is not a combination listed in any M-38 Parts lists.
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Gary 1952M38A1
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Re: Pulley Issues - Water Pump, Alt & Crank Shaft

Post by Gary 1952M38A1 » Fri Nov 10, 2017 2:33 pm

The Omix Ada pump went back to the vendor, my NOS water pump arrived today :D . All I need now is the right pulley for my Alternator. Just for the record, I did not do the 24v to 12v conversion and I am thinking when the University owned it they probably did it back then in the 70's as parts were more available to then for civilian jeeps than military.

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Re: Pulley Issues - Water Pump, Alt & Crank Shaft

Post by pajeff02 » Sat Aug 11, 2018 1:45 am

I just swapped out the civilian water pump (which has two different grooves) with a pump identical (or very similar) to the one pictured on the left in the first pic. The belt alignment appears to be pretty good, however, the space between the belts is tighter at the water pump than it is at the crank or generator pulleys. Not a deal breaker in my book as I can now run dual belts, but kind of disappointed that it is not in fact correct.

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Re: Pulley Issues - Water Pump, Alt & Crank Shaft

Post by Joe Gopan » Sat Aug 11, 2018 3:11 am

All three pulleys have their grooves in the same plane on the M-38A1, change any to add a non standard alternator,etc., and you are in unchartered territory.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
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Gary 1952M38A1
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Re: Pulley Issues - Water Pump, Alt & Crank Shaft

Post by Gary 1952M38A1 » Sat Aug 11, 2018 9:18 am

I saved a lot of time by taking a trip to my local starter alternator rebuilding shop, took the single grove pulley that was on the alternator and my new correct 2 grove waterpump and had the shop search in their pulley bin. They came up with one that worked like a charm, I now run a complete 2 pulley system that is aligned perfectly.

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Re: Pulley Issues - Water Pump, Alt & Crank Shaft

Post by Joe Gopan » Sat Aug 11, 2018 9:48 am

Jeep also had a late waterpump with unsymmetrical twin Groove Pulley that went to an emmssions pump on 70, 71 Commando and CJ-5
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO


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