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MGC Window Washer Pump Rebuild / Replacement

Moss Motors
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55-60MG4KM Avatar
55-60MG4KM Silver Member Keith Meyer
Corvallis, OR, USA   USA
OK, I’m being a bit anal here but what the heck - I've been looking for a replacement for my original MGC window washer fluid pump (BMC P/N: 13H3989). The pump motor still runs with 12V applied but the unit does not pump. Presumably the pumps internals are worn out. The original P/N was 13H3989 which was superseded by GWW124 (as shown in my factory parts manual) which may have been superseded by GWW125. The only currently available and offered pump that I can find is the Lucas WSP100 pump which is too tall to fit under the fender without turning it upside down. I have seen a pump offered under the P/N of GWW125 but what it really is a fully plastic aftermarket alternative pump that is too tall to fit in the correct mounting location. I have been calling around trying to find someone who can rebuild the original pump without much success. Thinking out of the box - I'm even thinking that I might be able to use the guts or parts out of the WSP100 to rebuild my original pump. Does anyone have any information, suggestions, reccomendations or ideas? Thanks, Keith

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ga duke Avatar
ga duke Mike Dooley
Newnan, GA, USA   USA
The original pump has a small rubber impeller that gets tired with age...I have no knowledge of the internals of the replacements, can only suggest that you buy one and take it apart for investigation...a $15 experiment if you will.
Do not mount the pump with the motor on the bottom in case the seal fails a causes a short...my 2 cents...

M

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55-60MG4KM Silver Member Keith Meyer
Corvallis, OR, USA   USA
This is still a work in progress but here are some notes about what I have found so far.

• I looked up the pump in my original factory Service Parts List. My pump has no part number on it. The original P/N shownn in the list is 13H3989. My Parts List shows a replacement number of GWW 124. I have pretty much confirmed that GWW 124 was replaced by GWW 125. GWW 125 was replaced WSB 100.
• I have searched and found only one location that offers a GWW 124 pump but they have no information posted about the pump itself, not even a picture. They say they are updating there web site to better show the part but at this time there is nothing shown.
• Additional information indicates that GWW 124 was a metal version while GWW 125 was a plastic version. I’m not sure what the metal /plastic designation refers too. My pump, the GWW 125 and the WSB 100 versions have a plastic pump. I have not seen a photograph of GWW 124. My pump motor is covered in plastic. Pictures of the GWW 125 and the WSB both show a metal cover on there motor. The GWW 125 and WSB appear to be identical but I have no way to compare them to one another.
• If the GWW 125 appears to be dimensionally identical to the WSB 100. The WSB 100 it will not fit in the location without turning it upside down. Also, I do not know if the mounting holes match those on the vehicle.
• I have ordered two GWW 125 pumps but have not received them yet. My thoughts are:
o If the mounting holes align I might mount one upside down.
o Using the second pump, if the pump operating parts are a match I can move them into the original pump.
o Again using the second pump I can possibly mount the new pump intact onto the old motor.
• I have ordered (Amazon) and received a small Keenso 12V Universal SI-A0050 pump. Although much smaller than any others I have found it is still too tall (@ 2.5"winking smiley to fit in the correct mounting location. Further, the C/L of the pumps mounting bracket holes do not match those on the car, they are way too wide. To use this pump it would have to be mounted upside down.
• I have found no one, so far although I am still waiting on one response, who can rebuild the original pump.

More to come.

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Attachments:
Keenso Pump (1).JPG    17.9 KB
Keenso Pump (1).JPG

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mainelymgb Avatar
mainelymgb Rich S
MA, New England, USA   USA
Keith,

Two years ago, I replaced that part on my C. The new one resembled the old one and has functioned properly. Either one could only be installed one way. I would have to research my receipts, but it came either from Moss or Robert Kirk.

Follow polarity to not run the impeller backwards and prime the input line with fluid to start.

Photo attached. Hope this helps.


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IMG_20190226_165410178_HDR.jpg

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55-60MG4KM Avatar
55-60MG4KM Silver Member Keith Meyer
Corvallis, OR, USA   USA
Rich: Thanks but dont bother looking up the information as your photo shows a pump that looks very much like the GWW 125 or WSB 100 as they both look similar if not identical. I may end up mounting it upside down as you have. Keith

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barn504 Avatar
barn504 malcolm cook
saffron walden, essex, UK   GBR
Had the same problem with mine.
It turned out the gasket that holds the pump together was letting air in.
Worth a look.
Malcolm.

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55-60MG4KM Avatar
55-60MG4KM Silver Member Keith Meyer
Corvallis, OR, USA   USA
Final Report (For Now): So the only source that I have found who said there pumps are GWW 124 pumps is RevingtonTR (www.revingtontr.com). Revington is a nice TR site that I passed on to a buddy with a TR 6. However, if you look at their picture of the pump it looks amazingly like the GWW 125 and WSB 100 and nothing like the 13H3989 shown in the Service Parts List. So, I bought two GSW 125 pumps with hopes that I could take the guts out of one and use them to rebuild the original pump. The good news is that the newer pump impeller mounts to the drive motor in the same manner as the original. However, the new impeller is a larger diameter and for it to effectively work in the old pump each of its rubber blades would need to be cut down to fit. Further, the old pumps drive shaft seal has expired and in the design of the original pump water would leak out of it. At this point I do not want to take the time to fiddle with updating the old pump but with patience I think it can be done. So, for now I mounted the second pump as shown in Rich’s photo. I have had to run new lines to each of the nozzles, install a new “T” and install a “non-return” valve but I now have a washer system works. If anyone ever finds a source of pumps that look and fit like 13H3989 please let us all know. Thanks, Keith

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