Water Pump

[Richard G.]

I'm helping a neighbor assemble his engine and the waterpump he has I can't identify. Can anyone tell me what this pump was used for, the style looks correct but I can't figure-out what it was used for. The number looks like 3640860, of course the 6 could also be an 8, but I'm pretty sure its a 6. Thanks in advance

Rich

[Jack H.]

Re: Water Pump

First, your copy of the Judging Guide should tell you what cast number is appropriate for a given engine's water pump. Second, if a pump is not factory concours correct for a given application, does it really make a difference where it came from/what it goes to? Third, beware of aftermarket, non-GM pumps!

They can look similar in body outline but bear non-GM casting numbers on them--you won't find a 'GM' emboss on the body of these pumps. The number you give doesn't look like GM to me....

[Joe L.]

Re: Water Pump

Rich-----

If it's a big block water pump application, then the number is likely GM #3940960. This waterpump was used for later 1969 through earlier 1970 Corvettes. It is similar to the earlier 3856284, but with a bit more reinforcement around the snout. This waterpump casting was used only for Corvettes and, possibly, some MD/HD trucks. By the time that it came into existence, all other big block applications had "converted" to the long leg style pump.

If it's a small block application that you're dealing with, then I have no idea what the pump is. There is no small block casting number ever used which is even remotely similar to the number you provided.

[Richard G.]

Re: Water Pump

Joe

Thanks very much for your response. I believe, as usual that your absolutely correct. The pump is for a very late built 1969 435 BB and I believe that the date on the pump is J30 9, which works perfectly. The car only has 17k miles on it so I believe that it is original based on it's documentation. The JM only lists the 284 water pump and so this might be a good edit to the JM. During my research, I came accross another WP with a different number that was also used later in 1969, I don't have that number with me. I not sure how to get something like this added to the JM, but it's usefull information any way you look at it. Most people look for the 284 WP listed in the JM.

Thanks again Joe

Rich

[Terry M.]

Re: Water Pump

Rich,

Send your information on 1969 WPs to the 1968-1972 National Team Leader - listed on the third page of The Restorer. That is how changes and additions are made to the TIM&JG.

[Joe L.]

Re: Water Pump

Rich-----

The 3856284 and the 3940960 are the only 2 waterpump castings ever originally used for 1969 Corvette big blocks.

[Richard G.]

Re: Water Pump

Joe

Thanks again. I was told by a Gentlemen that restores Water pumps and Fuel Pumps that there was another water pump used, number 3992077. Let me know what you think.

Thanks

Rich

[Joe L.]

Re: Water Pump

Rich-----

GM casting #3992077 was never originally used on a 1969 Corvette. 3992077 was first used for the 1971 model year, although I would not rule out the possibility that some were used later in the 1970 model year. Certainly, none were used for 1969.

[Richard G.]

Re: Water Pump

Joe

Thanks, good to know, I'll relay that back to the rebuilder. Again, thanks for your help

Rich

[Joe L.]

Re: Water Pump

Rich------

I believe that the 3992077 casting was used on a 1969 when someone shows me one with a 1969 casting date. I won't hold my breath until that happens, though.