Water Pump

[philip]

I was giving everything under the hood a last lookover this afternoon before heading out to the desert heat tomorrow.

Thought crossed my mind that for all know, the water pump in this ol truck may well be the original ... 24 yrs and 166k miles (note: Later, I called the original owner ... he says he never replaced the w/p).

I put a new fan belt on the thing 2 weeks ago but didn't give the water pump a close check for shaft play. There were no leaks present.

Well today, I checked shaft play and ... OOPS! There's quite a bit of play. Yeah, I made sure it wasn't the fan clutch I was feeling knocking about.

Time was ripe to replace the pump. It's surprisingly easy. Took about 90 minutes.

One thing of note: The replacement pump (GMB) is different in one respect. The one bolt securing the alternator bracket can be reused but ... the other two bolts had to be replaced with ones 10 mm longer than what I took out.

The OEM "N" pump uses one each:

8x1.25x40mm shouldered bolt
8x1.25x45mm shouldered bolt
10x1.25x55mm shouldered bolt.

A/C compressor and alternator are not in the way.





Slightly used pump I bought on eBay awhile back installed. In the background, notice the lower radiator hose as it passes by the alternator. The "With A/C" hose is a two piece affair with a 90 degree metal elbow in the middle. The portion you see here is only the lower part of the "non-A/C" hose whose bend keeps a much more respectable distance from the alternator fan blades.



The original cast iron pump measured 0.019" radial play. Makes quite a "clunk" and yet, no coolant leakage.

[ffdjm]

Water pumps in my 1981 diesel 720 have been averaging 75k miles between replacements. I am considering rebuilding the old pumps. How difficult might this be?

Douglas

[EvergreenSD]

How many miles have you put on your diesel? Sounds like alot, I'd sure be curious to hear who has the most miles on an SD.

[philip]

Water pumps in my 1981 diesel 720 have been averaging 75k miles between replacements. I am considering rebuilding the old pumps. How difficult might this be?

Douglas

Difficulty vs cost and success. You will need a Big Press.

Thank you but I'll buy it from a reliable name rebuilder or in some cases, the things are new (casting, impeller, and all!)

The thing that will shorten the life of ANY water pump is too much belt tension. A squeaky belt is a glazed belt. I've learned to replace glazed belts instead of over tightening them.

[asavage]

Water pumps in my 1981 diesel 720 have been averaging 75k miles between replacements. I am considering rebuilding the old pumps. How difficult might this be?

Many years ago, I had a couple of Hillman 1390cc water pumps rebuilt. At that time, it was possible to order the bearing/shaft "cartridges" as a commodity, and we chose a ceramic seal cartridge that fit fairly closely and machined the pump's housing out a bit to accomodate it. It wasn't all that difficult, but then I had a very patient and accomodating machinist on tap.

I'm surprised at how few miles you've been getting on yours. Which is failing first: the seal or the brgs? Or, by the time you know about it, are they both bad?

[dieselscout80]

My old SD 22/33 manual shows how to rebuild the water pump. I had one rebuilt by a shop and it worked great.

I would bet that asking at a good parts store (not a chain store) or service shop you could find someone local to you.

Carey

[philip]

My old SD 22/33 manual shows how to rebuild the water pump. I had one rebuilt by a shop and it worked great. SNIP

Carey

While the SD22/33 suppliment manual 1st Revision shows the pump's component parts, it does not outline a rebuild procedure.

[philip]

"There's never enough time to do it right but ... there's always enough time to do it over"
-Jack Bergman (I hope)

The GMB water pump I installed and put a bit over 600 miles on in one day ... failed. I was hoping to avoid all that, right?

This morning while doing an underhood check of everything after yesterdays trek to Oatman, AZ and back, I noticed coolant on the ground! The reservoir was empty and the radiator was only down a 1/2" from full. WHEW!

After close inspection with a mirror, coolant was escaping from the weep hole. THEN I noticed something odd. The support bearing appears to have shifted forward (out) of the housing about 2.5mm ! I cannot say if this is normal for GMB pumps or if the condition existed before I installed the pump but ... it's sure there now and the pump weeps.



So, off with that pump and on with a brand NEW Airtex (PN: AW9198) which turned out to be the same "N" brand of Japanese manufacture as the OEM cast iron pump I originally replaced. Retail price $99.99 . A rebuilt from the same parts store would have been only $10 less.





Vane design is identical to the OEM pump.



Here's the GMB vane.

[kassim503]

I have a GMB water pump on the maxi right now- after reading this I rembered that mine is on its way out- 4k miles and I have play in the bearing, you can feel the gap with the metal fan.

I also have the same hub design as the GMB pump on yours- 1.28 then tapers down to 5/8ths, also the 1.28" part was pressed onto the 5/8th shaft

Also on top of that I have the same kind of vane, a piece of steel bent at a right angle

Could GMB pumps be low quality? I asked for GMB because I heard they are good for japanese cars, could I have heard wrong?

[asavage]

GMB is "supposed" to be a decent water pump. However, I don't like the feedback I'm seeing from you two, and though a formed steel impeller works fine, I sure like a cast impeller, given a choice.

[kassim503]

The GMB water pump I installed and put a bit over 600 miles on in one day ... failed. I was hoping to avoid all that, right?

When you where driving, was it hot out? Was the a/c running? I have idea about the failure of the gmb pumps

The GMB pump on the maxima has the same exact problem. The WP is leaking from the weep hole and the shaft seems to have pulled out by an 1/8th to a quarter inch.

Obiously I was not planning on resuing the GMB pump because I was afraid of the fan spiraling into the radiator, so just out of curisoity I got my hammer and tapped on the shaft, with 2-3 taps the bearing was back into the pump. I think that the fan pulling when its locked up makes enough force to pull the bearing out of the casing, then water runs through the newly made gap and exits out through the weep hole.

also when i hit the impeller side of the shaft the support bearing slid out with 2-3 hits.

[philip]

When you where driving, was it hot out? Was the a/c running? I have idea about the failure of the gmb pumps. SNIP

My answer redirects this thread into air conditioning

[crzhors]

Hello I'm new here.I have an SD 22 in my boat,calls itself an M4-33.I'm coming back to the US from Panama and need a waterpump,pref. a new one.Can anyone tell me of a large distributer that may have them IE Carquest,Napa etc.? Thanks,

[philip]

NAPAonline.com lists -new- N brand (OEM) pump for the SD22. $66.95 The "N" brand is also sold under the AIRTEX name.

Since you read this thread, you know what to watch out for.

The SD2x for the Marine versions use the longer axle and a deeper pulley offset which is the standard SD33-six.

[ecomike]

I see that NAPAonline.com has three pumps, one rebuilt, one new aluminum and third that looks like the "N" cast iron pump, No. NWP559198 , which is the most expensive, $66.99. If it is the cast iron, for that small difference in price I will get a new one.