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I have mounted an aftermarket dual pulley water pump sourced from QTM to my M38 restoration, with the goal of returning it to the more original 2 belt configuration. The prior owner was running a single pulley water pump, the existing dual crank pulley and a jury rigged alternator on a single belt.

There is a significant misalignment between the pump and crank pulleys. The picture doesn't show it well, but the REAR sheave of the pump pulley is almost aligned with the bottom FRONT sheave of the crank pulley - the pump pulley is forward of the crank pulley.



The crank pulley is of the stamped and laminated variety - ie. not cast iron. It looks like many dual pulleys I have seen used on CJ's. It is sitting close to the timing cover, but not touching.

I will be mounting an alternator with a dual sheave pulley on an adjustable mount, so it is not a factor. I will adjust the alternator mounting to align with the pump/crank pulleys.

Do I have a mismatch of parts, or is there something else going on here??



Thanks and regards, Jeff

This may be a silly question but the crank pulley isn't on backwards is it?

The longer snout side, the area that rides in the seal in the timing cover, is installed inboard, and there is an oil tight seal. I think if it were backward it would leak at the seal.
Sorry I don't have a close up shot of the pulley on the crank.
Thanks,
Jeff

The problem is that the pulley on the water pump is not pressed on to the pump shaft enough... there was a problem with this a few years ago that was posted here...

I had one similar, what I did was brace the center of the shaft and press the pulley on further to make it fit... Is easier if you have a Hydraulic press...

I used a BIG C clamp and a socket to press mine on... or set it on a block of oak and tap it on with a socket and a brass hammer, cannot remember... Not the best of methods but it did work...

Just be careful and do it slowly...

My 2C on the problem...

I've got right at 3/8" between the back of the pulley and the face of
the bolt sticking out forward on the water pump in your photo.

Thanks Gentlemen, that is actually good news and something that is do-able.

Thanks also for the 3/8" reference measurement. I will start by checking that before I start taking it apart.

Any other tips welcome!
Cheers,
Jeff

You have the wrong crankshaft pulley--the one you have is for the civilian jeeps and is not a true dual fan belt pulley. The second grove is for the governor belt. Before moving the water pump pulley--source a M38 (M38A1 is the same) crankshaft pulley and see if all lines up as it should.

Good catch Harold. These guys should have noticed the front sheave is wider then the back sheave!

A note to the wise on pushing that pulley on further on the water pump. Hal mentioned supporting the shaft. He knows that is an important necessity. However it was not made clear that we are talking about supporting the pump shaft at it's rear side so it stays flush to the rear edge of the impeller. Even then you still risk damaging the pump shaft seal. Do a thorough read of the TM 9-1804A Engine manual Water pump overhaul pages 58 thru 61.

Wow, you guys are amazing. Thanks for catching that.

I have listed a Wanted To Buy here in the wanted section of the forum. Let me know if you have one for sale....
Regards,
Jeff

It appears you have a newly made water pump manufactured by Crown. A company based here in Mass. I also had the same problem with that pump pulley. I ended up taking the pulley off and turning the rear of the pulley on the lathe. This allowed me to position the pulley in farther so that they all lined up perfectly.

Hope this might help you out.

Have a great day!

~ Matt

The sheaves on the crank don't match. He won't be able to use two stock
belts. He has to solve that issue as well.

4x4M38 wrote:The sheaves on the crank don't match. He won't be able to use two stock
belts. He has to solve that issue as well.

I agree Brian. It does appear that he might have two problems to solve here.

~ Matt

I've got a proper M38 double pulley on the way to my from one of the forum members. I will install that first and then see where they fall.

Thanks Matt, for the warning on the Crown part. I can't believe I keep buying this S#i! Are you just ID'ing the Crown pump from my photo? Is there some marking on it to confirm it is one of these Crown pumps?

To clarify, you removed material from the rear of the pulley shaft area so it would seat further on the shaft? How much did you have to remove?

Thanks, Jeff

Matt - it appears the crank nut used on your pulley is different that the nut I currently have. The one currently on the M38 looks like most of the other CJ nuts I have seen.
Is the crank nut different for the M38 pulley?

Jeff,

I can't be 100% positive that you have a Crown water pump but it sure looks like it from the pictures that I'm viewing. That distinctive one piece double pulley, instead of a two piece sheetmetal pulley.

Like you mentioned, get the correct crank pulley on and then check the alignment of all of your pulleys. Hopefully that is all you need... but I mention my dilemma just in case you run into the same thing.

Yes I was able to take off just enough on the rear of the water pump pulley using the lathe. I had to do this on mine in order to make room to push the pulley in further. If you look at my picture above you can see my shaft sticks out the front a little more then yours currently after I aligned it. I don't remember the amount I took off and your probably better off taking your own measurements as mine might be different from yours.

I have the hand crank nut on mine. You have the normal one that you can't use a hand crank on. Its a cheap part if you want to "upgrade". Not really needed though. Ryan's M38 book shows both being used.

~ Matt