I bought a rebuilt 36 chevy water pump probably 2 years ago from a company that specializes in that type of work. It's taken a year and a half to get my motor rebuilt so I just tonight attempted to put the water pump on. Unfortunately the mounting holes don't quite line up so I can't get 2 of the 3 bolts in. The new pump has casting numbers 837509 and 836076. I can't find these numbers in my limited manuals so can someone help identify this pump? I can't find any casting numbers on my original pump unless they are under the pulley. I might note that my block is from a Canadian car, but the casting number is correct for a 36.

Also, do you recommend putting a gasket sealer on the water pump and if so, what kind.

Thanks for your help.

837509 is the correct part number for the water pump body (with bushing) for all 36 Chevys according to my 29-42 parts manual.

Interesting. Wonder why it doesn't fit. Is the part number and casting number one in the same?

I have a 12 page document that lists casting numbers in sequence for 29-42 and I don't see 837509 listed.

The number on the item is the casting number, and not the part number. The part number is not on the item.

I suspect you may have a '35 water pump. Does it have a bleed hole near the bottom mounting hole? If it's a '36 it shouldn't have the bleed hole.

Here's some info from the 29-41 parts manual, and the 29-54 parts manual:

Cast # for 35 = 837610; for 36 = 836078
Body # for 35 = 837609; for 36 = 836076
Assy # for 35 = 837608; for 36 = 836075

Hope this helps.

Wally

Most part numbers differ from casting numbers, but not always.
The older parts books did not list casting numbers.
My 1940,1944 books list the water pump body part # as 836076 as the part # for the 1936 water pump body. The 1952 book no longer lists the body seperatly but shows 836076 as the casting number for the 1936 complete water pump which has a part # of 836078.
The only place I find 837509 is for a carburetor jet.??
The # 837609 was the part # of a 1935 pump which had a casting # 837610. What part of the pump is this number on?
The 1935 pump had a smaller impeler and the opening in the block was slightly smaller. The 1935 gasket description says 3 3/16" round center hole , 3 5/15" holes and one 1/2" hole.
The 1936 gasket has a 3 1/4" center hole, and 3 5/15" holes.
Are you reading the 837509 # correctly?

Thanks all for your replies. I guess I don't know what I've got. It sure looks pretty though even if it doesn't fit.

I do not see a bleed hole near the bottom mounting hole.

Based on the dimensions of the gasket, it's a 36 gasket and when placed over the 3 mounting holes on the block they line up. When I place the gasket on the pump, the holes are off.

It's possible, the 837509 is 837609, but it sure looks like a 5 especially when compared to the 6's in 836076. (I did have cataract surgery Wednesday...)

The casting numbers I am seeing are on the bottom of the body of the pump, close to the pulley.

Not sure what to do other than to get my original pump rebuilt.

What about the gasket sealer? What do you recommend?

Whats wrong with your old pump? Replace the seals, check the end play and give it a try. Also 1936 pumps and kits pop up on ebay quite often
I never use anything for a gasket sealer.

I had the same experience. Never got to the bottom of just what the problem was - I simply rebuilt my old one and now I have a paperweight!!!

If the person that sold you the pump is still around I would ask him what the problem was. He may realize his mistake and offer you the correct one to fit your engine. It might be that easy!

Okay, I'll attempt to rebuild the old pump if someone can tell me the correct way to take it apart. The impellor is very rusty but maybe it will clean up.

I have attempted to contact the seller, but no response so far.

footbiz, I feel a little better knowing you had the same problem.

If you are going to rebuild the old pump don't use the old impeller or shaft. Get a new repair kit instead since the kit contains everything that you will need for rebuilding the old pump including a brand new impeller and shaft.

Thanks Mr. Dog, didn't know the impeller came with the kit. Some day I may actually get to use the carb you rebuilt for me.

The pulley is just pressed on the shaft. You can use a puller or you can drive the shaft out of the pulley. Loosen the packing nut and the impellor and shaft slide out. Drive out the bushings as needed and replace them. Repack with new seals, either lead washers or graphited rope.

I would not recommend "driving" out and of the parts. They should be "pressed" out and pressed in. It is highly recommended to either pulling off the pulley with a properly designed puller (contacts the majority of the pulley and uses the center shaft to push against) or pressing the shaft from the pulley either supporting the entire pulley or the housing with a support between the back of the nose and the packing nut. More than one housing has been broken without the support! Also make sure that the bushings are the correct size (both inside and out). Housings have been broken trying to press in new bushings that were only a few thousandths too big. Right dogface?

I have better luck grinding a slot in the impeller. (You are going to replace it anyway) With a deep slot you can use a chisel and break it apart. With the packing nut loosened you can remove the pulley and shaft out the front. Now you can safely remove the pulley in the hydraulic press. Now all you have to worry about is to insure you have the proper size drift to remove and install the bushings.

I have these water pump kits if you need one. bwbugayaol

Absolutely correct Dippy Chippy!

Wish I would have read these posts today before I attempted to take the pulleys off the old and new pumps. My plan was to use the new parts from the rebuilt pump on the old body that fits. I started with the old pump and all I accomplished was to distort the pulley. I then put it on a press and pushed down on the shaft, thinking the housing would break at any time, but the shaft broke loose. Still couldn't budge it with the puller, so went back to the press and between it and the puller, finally got it off. Attempted same thing with the rebuilt pump and couldn't budge it with the press. I finally noticed there was a pin going through the pulley and shaft. Knocked it out and finally got both pulleys off, after many hours. The shaft, impeller, and bushing were the same for both pumps, so I used them in my old pump.

I'm not sure whether I messed up the packing taking it out and putting it back in. I would feel better with new packing. Can I buy just the packing somewhere? Didn't see it at the Filling Station. Bruce, do you have it?

I'm hoping the pulley will press back on easier than it was to take it off. I think the trick will be to line up the hole in the pulley and shaft for the pin. Thanks again for all your help.

The "shaft, impeller, bushings the same"??? The 1936 used a different shaft and impeller than a 1935. Buhings were the same. I believe that the impeller was larger in diameter and wider in 1936. Did they goof and uses 1936 parts in a 1935 housing for your rebuilt pump?

Gene, if I understand what has been said about the casting numbers, the rebuilt housing is a 36, but the holes just don't quite line up for some reason. Doesn't a 35 have 4 mounting holes and not 3 like I have? Anyway, if I can find new packing I think I'll be set. I did finally find a casting number on my old pump after bead blasting and it's 836076 which I believe agrees with what's been said.

One last stupid question. There's a place for oil at the front of the housing. How does the oil get to the shaft and inside the bushing? There's a groove around the housing for the oil, but no holes in the bushing.

The only stupid question is the one not asked!

The bushing is sintered bronze, and is porous. By filling the cup with a few drops of motor oil, it penetrates the bushing and lubricates the shaft. I recall that my shop manual suggests adding oil to this and other locations every 1,000 miles or so. The rear bushing is lubricated by absorbing grease from the inside of the water pump

Do you have an owner's manual and/or shop manual for your car? If not, they're both usually available on eBay.

Hello, There are rebuilt water pumps for sale on ebay. This one is listed now with 13 hrs left. Item number 200309710585

I think it was 65.00

Regards,
Ken

Thanks again everyone for all the good information!

I finally dug out my spare pump. It was marked by a vendor on a piece of tape "1935 Chev" It is brand new without the grease cup. It is painted green. There is no GM logo to be found. The pulley has two cast numbers as does the body. With what I found in my 29-40 parts book, they are: Pulley 837872 (32-36 all), 837035 (unknown), Body on the bottom under the pulley end 837609 (1935), 836076 (1936). There is no drain hole but there is a depression in the body at the lowest point where one might have been drilled. I hope this adds to knowledge rather than confusion.

Well, everyone who tried to tell me that the rebuilt pump housing was a 35 was correct. Blind me did not notice that the drain hole had been tapped and a plug inserted. So as Gene had suggested, they put 36 parts in a 35 housing. Finally got in touch with the company and they are going to buy back the 35 housing for $30. If someone else is interested in it, let me know, it's in pretty good condition. If I can just get the pulley on now without breaking something then I'll be set.

Perhaps this is kicking a dead horse but...
I have on my bench two nos GM water pumps. One is 35, one is 36. Both have two casting numbers on the body, one is for a 35, one is for a 36. Neither has a drain hole. One has a cast iron pulley again with casting numbers for both 35 and 36. The 36 pump has a stamped pulley with no numbers. The only difference in the two is that the 36 impeller is about 1/4" thicker and would project that much deeper into the block. Both pumps are painted green. I have been running a 35 pump in a 36 block with some coolant loss and/or overheating. I think the impeller is the answer.

NOS pumps were not painted??????????rebuilts were. A mixture of parts?????????

You have arrived at the answer for the heating problems on a 1936 engine. A '35 water pump will not move enough coolant to properly cool the engine.

Also the 1936 block does not have the baffle behind the pump so the longer rotor is necessary.

The '36 engine coolant capacity was increased significantly over the '35. If memory serves me..and I may be off here...the '36 has 5 quarts more capacity over the '35.
The '36 uses full length water jacket on the cylinders and needs the deeper water pump to move the larger capacity.

Everyone is probably correct but the baffle exists in 36 but is cast in place rather than inserted. I think that the inefficiency is the result of the smaller impeller in a big cavity.

I agree. The larger the gap between impeller and cavity the lower the flow. Water just moves around the impeller instead of being moved in the intended direction.

I just bought on ebay a water pump repair kit, which was listed as being for 1929-34. I'm working on a '29 engine. When the kit arrived, it was actually a 1935 kit. The box is labeled as follows:
QUALITY BUILT
WATER PUMP
REPAIR KIT
Chevrolet, All Models 1935
Price $2.20
No. 4320 837608K

Looking at the contents, they look at first glance to be just like the '29-'32 ones I'm used to. Would this kit work for my '29, or is there some difference that would keep it from working? Actually, if the impeller and bushing are the same, I can dig up the rest of the parts to do the job. So which parts are different? It would save me lots of measuring and checking if someone knows the differences.

Thanks for any help you guys can provide.....

All the Best, Chip

Chip,
According to my Parts catalog, the front bushing is the same but the shaft and impeller assy. are different.
Since the bushing is the same that means the shaft is the same diameter. If the impeller is the same and the shaft is longer, you are in business. Good luck.

Mike

The impeller was made larger in 1935 and enlarged again in 1936.

Thanks guys..... I guess I'll just have to buy a nice '35 car with a bad water pump! Perfect.

All the Best,

Chip

I like the way you think.

Mike