Water Pump

[Chuck W.]

Does anyone know of a source for the water pump bearing retainer spring (#636298) on the 4-134 engine? I have looked everywhere and it looks like the water pump rebuild kits offered by suppliers come with everything EXCEPT the spring. Has anyone tried to make this spring from 16 gauge spring wire?
Thanks.

[Rus Curtis]

Chuck,
Reading your other post asking about this clip's existence, got me to looking.  I googled but didn't find much.  I looked not only at the military vendors but just out there in general.  I then wondered about the modern replacement water pumps available everywhere.  I wondered if they used this clip (where would they get one?) or a modern spring clip as a replacement (is there space for a modern bearing retainer?). This post has the first image I've seen of this clip. 

I also thought about how difficult it would be to make one.  Have you tried the google feature where you can search for an image?  Worth a try.

[Chuck W.]

Rus, after the recent water pump issues on my 3B, I decided to read up and see what it would take to rebuild these pumps, plus, I wanted to see what happened to the pump that I just took off, as it was less than 5 years old.
It seems that the biggest thing is to remove the pulley without damaging it. They sell a special puller, but I just made one:
This is a double pulley M-38 pump:

Once the pulley is off, there's not much else to it, hardest part is getting the bearing retainer spring out without tearing it up.

I took 6 pumps apart and 5 were all the same, but the 6th one, the one I just changed out, was very different. It had a completely different seal, impeller and housing. I think these are aftermarket water pumps. They have a round weep hole instead of the slot, and they don't use the bearing retainer spring.

Anyway, I'm going to rebuild the original pump that I took off several years ago, just in case the new one fails early, and I suspect it will.

Parts seem to be readily available, except for the spring, and cost is less than a new aftermarket pump. I think I'd rather have the original type pump.
I did order some spring wire and will try to make some of the clips.

[Mark W.]

Yes you could make a new spring. I strongly suggest going to a model airplane hobby shop and buying a piece of the correct diameter piano wire to make the spring from.

[Ron D]

This is a double pulley M-38 pump:

Hi Chuck,
If you have no use for the M38 double pulley, I have a nice solid take-off CJ single belt pulley that I'd trade if you're interested?
Maybe throw in a few bucks to sweeten the deal.

[Chuck W.]

Thanks, Ron, but I am going to rebuild two pumps, one for my CJ3B and one for my M38, so I guess I better hang on to it.

Also: I think I may have found a source for the Brummer style one piece seal that is used in the reproduction Omix-ADA pumps (I guess that's who is making them).

[Ron D]

Thanks Chuck. Just thought I'd ask.
I fixing to rebuild a spare for my M38 as well.
Following your thread......

[Chuck W.]

I want to follow up on  the water pump saga and what I have found so far;
basically, there are two type water pumps, the original Willys pump (left), and the reproduction pump (right).

Externally, they look much the same and the reproduction pump is a bolt-in direct replacement, but look a little closer:
Here's the original Willys pump:



and here's the reproduction pump:



The reproduction pump does not have the slot for the bearing retaining clip and it also has a small, round weep hole. But the real difference becomes apparent when you turn the pumps over:
Here's the seal area on the Willys pump:


and here's the seal area on the reproduction pump:


and take a look at the impellers:


By my measurements, the shaft and bearing assembly is the same, although the reproduction does not have the groove for the retaining clip:


But the seals are totally different:
Old:
New:

While the rebuild kits sold by MV vendors will work in the old style pump, I have yet to find a rebuild kit for the aftermarket pump, but I am working on a source for parts. The 808129 shaft and bearing assembly is available from OMIX-Ada, and I may have found the correct seal assembly, will see when it gets here from China.
Stay tuned.....

BTW, here's an interesting rebuild kit i found recently:

I could use the shaft, impeller and clip, but I think I will just keep it all together in the original box!

[Ron D]

Hi Chuck,
Thanks for the great photos!

I'm currently taking apart an original pump that has the wire clip.
After cleaning crud out of the slot and letting it soak in PB Blaster, it's still being stubborn.
The clip still looks good (not eaten up with rust). I'm going to try a little heat next.

Does the straight end of that pin fit into a hole in the bearing shaft?
Or does it just ride in the slot?
Could you show a photo of it please? Even a bench photo of the pin in the hole would be helpful.
With the bearing pressed into the housing, that clip seems to be nothing more than a "safety" to keep the bearing in place?

Maybe I missed it, but the pump rebuild instructions in the Army manual don't mention indexing the hole into the slot on the body so the pin will fit and latch to the body.

[Chuck W.]

Or does it just ride in the slot?

Yes.

that clip seems to be nothing more than a "safety" to keep the bearing in place?

I think you are exactly right, with the impeller and the pulley pressed on, I don't think the shaft & bearing can move, anyway. The reproduction pumps don't use the clip.

I wonder if a good soaking in Evapo-Rust would help free up the clip. It may also be that the shaft & bearing has moved in or out slightly and pinched the clip in the groove. I don't think I would try heat, you might anneal the clip and take the spring out of it.

There is a groove in the bearing and a matching groove in the pump housing, when you press the new shaft & bearing into the housing, you align the two grooves and then the clip will slide into the groove. I don't have any photos of it right now, but check out Portrayal Press's excellent You Tube video:
https://www.youtube.com/watch?v=qsx1iUU92iM&t=386s

[Ron D]

Thanks Chuck.
I've seen Patrick's (Portrayal Press) video. It's very good, but doesn't really show the clip very well going in or out.
I'm glad to hear it doesn't fit in a hole but rather a slot.
Mine doesn't appear to be pinched, the slot in the bearing is exactly centered in the slot on the housing.

I'm approaching a decision point on mine.
The prime objective is to get it out without breaking it.
I'd rather not try and press the bearing out over a broken stub of a clip.
I'm willing to risk damaging the clip with a little heat so long as it comes out in one piece.

Depending on the condition of everything after I get the bearing out --- after rebuild I may run it without a clip if I can't buy or make a new one.
That slot in the body is at 12 o'clock so it's easily inspected (if I keep it clean) to see if the slot on the bearing wants to move.

Odds are I'm pole-vaulting over mouse turds (because new pumps don't use the safety clip) --- what's the worst that could happen if it did move? --- broken impeller more likely than fan eating the radiator? 

[Chuck W.]

Maybe just a touch of  medium strength Loc-Tite on the bearing-to-housing bore just to keep it from trying to move?

[Ron D]

Excellent idea!

Reminded me that Loctite specifically makes bearing retainer compounds (603, 609, others).
Will have to research which one is just right to do this job.
Don't want to cause future disassembly problem using the wrong one.

Thanks!

[Chuck W.]

Ron,
I am sure you know this already, but for others who might not, be sure to inspect this area of the pump, because this is where the ceramic seal actually runs. If there is any damage, pitting, rust, etc, the seal may not seat properly. It needs to be nice and clean and shiny.
The seal is one place where the reproduction pump is better, in my opinion. The one-piece seal presses into the pump housing for a more positive seal. As loose as the bearings were in my old reproduction pump, it never leaked a drop from the weep hole!

If you are reusing the old impeller, the top area also needs to be very clean so the rubber can seal.

[Chuck W.]

Still waiting on a few parts, but I started assembling the M38 pump today. I pressed the bearing and shaft assembly into the housing and carefully aligned the two grooves, then inserted the retaining spring. The spring slid into the groove with no problem, although I did give the spring a good coat of anti-seize, maybe it will help the next guy.