Correct Water Pump

[thomas g. warner]

This is exactly the kind of information that should be documented on
patricks site, ,maybe titled "confirmed correct parts for the GMC
motorhome". We discussed this same subject sometime ago but anytime a new
member comes on board it can come up again.

The correct water pump for the GMC motorhome MUST HAVE A 4 1/4" (not 3 7/8")
CAST IMPELLER WITH 6 CAST paddles. It should have part # 412265 AND MUST
HAVE A D24 stamped on it also. A cast pump with the same part # and a D2
or D11 stamped on it is not suitable. There may be other suitable part
numbers but I have not been able to find them. The D24 casting has a very
small cast bypass space betwen the impellers and the pump casting.

Just because a pump has a cast impeller, it may or not At 10:41 PM 12/9/98

>Mark,
>I just completed a job which included a new water pump. I ordered a new
>one through GM and recieved a steel impeller that was 3 1/2". I then
>ordered a rebuild and told my supplier to open the boxes and tell me the
>size of the impeller. He came back and said he had ones on the shelf with
>the same number with cast & stamped impellers, how about that! The OEM
>impeller on the water pump I pulled out was a 4" cast one.
>
>My sources do not have a special # for the larger impeller, it seems to be
>a matter of luck.
>
>I will have my suppliers check before they ship in the future!
>
>Jim Bounds www.gmccoop.com
>--------------------------

>>A new Water Pump was mentioned from Eaton GMC.
>>Anybody know if this was one with a cast impeller of 4 inches or 4 and one
>>quarter inches? Does it make a difference? Which one does Cinnebar stock?
>>I'm planning to carry a spare but I want the correct one.
>>thanks
>>Mark '77 Palm Beach NY
>>Hemogoblin's.com
>>
>>
>>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[thomas g. warner]

If you have a January 1997 issue of the GMC Motorhome Marketplace there is a
good article on water pumps and lots of pictures.(I really need to get a
scanner so we can share this kind of info). A picture is worth a million words.

I will try and describe what you should be looking for Arch. Hold the water
pump so you are looking at the impeller (side towards the engine) Point the
two hose connections straight up. Notice that there is now a depression
that looks like a fat Z, going from left to right. At the bottom of the left
Z and the top of the right Z you should see a nib that reaches almost to the
impeller. That nib should be very close to the impeller and be flat with
the gasket surface. The impeller should have 6 paddles and be 4 1/4" in
diameter. I would at least keep it for a spare even though it may be the
wrong one. A wrong one is better than none in an emergency.

>Thomas
>
>If the bypass goes back to the large hose connection I HAVE that too!
>My only problem is a D1 casting. So I must ask again do I keep it
>or throw it away? Thanks all.
>
>Take Care
>Arch 76 GB IL
>>
>> The correct water pump for the GMC motorhome MUST HAVE A 4 1/4" (not 3
>7/8")
>> CAST IMPELLER WITH 6 CAST paddles. It should have part # 412265 AND MUST
>> HAVE A D24 stamped on it also. A cast pump with the same part # and a D2
>> or D11 stamped on it is not suitable. There may be other suitable part
>> numbers but I have not been able to find them. The D24 casting has a very
>> small cast bypass space betwen the impellers and the pump casting.
>>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[thomas g. warner]

Sounds like you have it!

>In a message dated 12/10/98 12:55:31 PM Central Standard Time, warner
>writes:
>
>>
>> I will try and describe what you should be looking for Arch. Hold the
>water
>> pump so you are looking at the impeller (side towards the engine) Point the
>> two hose connections straight up. Notice that there is now a depression
>> that looks like a fat Z, going from left to right. At the bottom of the
>left
>> Z and the top of the right Z you should see a nib that reaches almost to
>the
>> impeller. That nib should be very close to the impeller and be flat with
>> the gasket surface. The impeller should have 6 paddles and be 4 1/4" in
>> diameter. I would at least keep it for a spare even though it may be the
>> wrong one. A wrong one is better than none in an emergency.
>>
>Thomas
>
>I have all of what you mention plus a cast in relief hole at the bottom
>of the right leg of the Z. How am I doing now? Thanks for all of your help.
>
>Take Care
>Arch
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[thomas g. warner]

Arch according to the article the D1 waterpumps are not suitable But than I
am not sure how hard the author tried to find other suitable pumps. I
believe the proof of the pudding is the physical characteristics of the pump
that I described. I know I can identify a good pump no matter what the
numbers are. 4 1/2" impeller, 6 paddles and small bypass nib.

>Thomas
>
>Then you think maybe there could be some with a D1 casting mark
>that might work? WOW this is fun how long have we been working
>on this. Being able to use a D1 casting might open up a lot of new
>cores. Just a thought.
>
>Take Care
>Arch 76 GB IL
>
>> Sounds like you have it!
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[phil swanson]

> I have my original water pump in a box along with a lot of other parts. I'd
> like to get it rebuilt as a spare. Any suggestions as to the best place to
> have it rebuilt ?
> Justin 77 PB

Where do you live? I have a place here in San Diego. Phil Swanson

 

[phil swanson]

> In a message dated 12/14/98 9:52:40 PM Central Standard Time, phil

>
> Where do you live? I have a place here in San Diego. Phil Swanson
> >>
> Oklahoma City
> JUstin

Justin,
I would think you can find a rebuilder in OK City. My guy uses heavy duty
industrial bearing and ceramic seals in his water pumps. I know they are pretty
much bullet proof.

Phil Swanson