I know this has probably been discussed a million times but I quickly couldnt find my answer and am in a bit of a rush. All of the water pumps that i have bought for my 72 cutlass with a 455, no a/c have been about 1/2 - 3/4 of an inch too long. None of the parts stores have any other listings for water pumps. My question is where does everyone get theirs?? thanks Dan

 

OK, here's a link dicussing different water pump lengths. Inside this post is a link to a reference of what should have come on what cars. It's also possible someone has mixed and matched the pullys. John

https://classicoldsmobile.com/forums...p-lengths.html

http://www.oldsmobility.com/oldsmo/v....php?f=6&t=391

 

thanks for that ling john. So if I get say a water pump for a 350, the only difference is the length of the shaft? In other words all the water pumps will physically bolt on it is just a matter of the belts lining up?
Ill hit the parts store and see what they have as far as the 350 pump.
Thanks again

 

btw the casting number is 408328 which the parts store said was a number in the computer but no listing for a pump..

 

Rockauto has them for without A/C. Some of the listings even have the pump length to help confirm your choice. They run about 35 plus the ride.

 

Yes. Sometime in the late 1970's they came out with one that didn't have two ports for the heater hoses. But they will all bolt up. I've not purchased a water pump through RockAuto but have got other parts and been pleased with the transactions. John

 

water pump 101:

Outside of Oddities such as the Missing Nipple issue, the "wrong side" inlet 1964-only 330-only unit, and that oddball V6 Diesel serpentine belt drive unit that rotates the other way... there are two main features of the Olds V8 water pump that matter as far as FITMENT, never mind correct function...

1) LENGTH overall from gasket surface to pulley mounting surface. Affects pulley position and therefore alignment. Place a straightedge across the hub surface where the pulley would be, and measure to the gasket surface. The flavors are [give or take a little]:
5.1" - early [pre-70??] no-AC
5.6" - Early AC and later No-AC
6.1" - Later w/AC and then pretty much ALL V8's after oh 1975 or so

2) Inlet nipple diameter - where the radiator hose fits on.

Other differences such as the type of impeller and the diameter of the housing volute ID and of the impeller... might matter to function under extreme conditions, but can likely be worked around.

I have a free Excel database with most of the known castings listed, how to ID them, maybe what they came on so you know what to tell the parts guy, crucial dimensions, what pulleys they use, etc. Free upon request. Nearly worth it too.

Consulting that, without listing every individual casting ID, I see IN GENERAL:

5.1 long x 2" inlet = the shortest earliest type.

5.1 x 1.8, typical large casting ID on the RH outlet boss is "1" or "2". Yeas, 1.8 is shorthand for 1&3/4 inches. Applications mainly 71-72 w/o AC.

5.6 x 2.0 - HD Cooling 68-69, maybe the '70 W30 &c with HD Cooling. Includes the rare and now pricey "X" 404847 casting. Also the 400268 or similar misread 400xxx numbers, typically with a large "O" on the RH outlet boss. And, no, it's not on YOUR right as you face the engine from the front, it's on the CAR'S RH side.

5.6 x 1.8" - seem to be for 70-72 SB/Non-HDC apps

6.1 x 1.8 - far and away the most common. Most mid-year-range apps w/AC, and almost all of everything since oh 1975 or so. Includes the ubiquitous #4 casting 412265, #3-407536, O-404562, and some other less common and aftermarket variations.

Evidently factory castings are getting rare and pricey, so if you find an "X" pump on that car in the boneyard... GRAB IT.

As for your problem, if your engine is not happy with the no-AC shorty, then just buy the AC type, right?
.+++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++

well, heck, I finally condensed the Known Castings to the following list and added that and the above "101" to the WP database for future use:

List of Some Known 1965-1990 Oldsmobile V8 Water Pump Casting ID's
5.1 x 2.0
[none] - 381288
[none] or "dot" ● - 398681
"O" - 384786
[none] or "dot" ● - 384783
[none] or "dot" ● - 404584

5.1 x 1.8
"1" or "dot" ● - 408328 [Note: "1" may look like a mere line, sans serif]
2 - 408329

5.6 x 2.0
"O" - 400269, 400268, or 400289 - Difficult to read cast digits correctly...
"X" - 404847 [Rare and getting pricey as of 5/2012]
"X" - 40484 [Factory "typo" or casting flaw??]
"O" - 30860 [probably not a factory issue casting]
[none] - 4841 [probably not a factory casting]

5.6 x 1.8
"2" - 408329
"5" - 418307, 413307, or 418807... Difficult to read cast digits correctly...
[none] - 31290, 30576, or 30948 [probably not a factory issue casting]

6.1 x 1.8
"O" or "3" - 407536
"4" - 412265
"O" - 404562
[none] - 31290, "O" - PH341, [none] - [no #]... [probably not a factory issue casting]
"O"- 22526206 = Later smog era FACTORY TYPE ALUMINUM water pump

 

Is this really what we've come to?

Mounting pullets?



- Eric

 

two holes, no waiting!



make sure your pullet mounting surface is clean before placing the pullet on that shaft!

 

And for the dimensionally-challeged:

P1010070-1.jpg

Also note the difference in the inlet diameter on the left and center pumps in the photo.

 

ok got it figured out. not listed anywhere apparently but ran the casting number and they were able to find me one. 30 bucks more.. but hey whatever works,

 

He 4424me,
Where did you order that 5.1 inch WP and what was the part number?
I,m having the same problem here in The Netherlands all they have here is the 5.6 and 6 inch ones.

 

I just went to my local supplier and they ran the casting number, which is 408328, they were able to cross it over on their system. It wasnt listed under a 455 or 350 for some reason. It was a auto extra brand. Hope this can help at all!

 

The SHORTEST pumps were used pre-68, before they had 455's or 350's... Try a '67 Cutlass with 330
5.1" no-AC
5.6" w/AC

presumably

 

I don't know about this. My engine has a 5.1" water pump, no ac on the car. The engine ID tag matches that of the last digits on the VIN. Mine is a 1972 Cutlass.

Albeit, someone could have gone through and changed all the pulleys etc. But that seems like a lot of work for no real gain. I'll tell you, it was a huge PITA finding the right pump.

*Sorry for updating a 2 year old thread. It came up under "new posts". Computer glitch?

 

Weird.

- Eric

 

Hey Joe you have the part # to the smallest water pump

 

Post #7 above here has ALL MANNER of part [well, CASTING] numbers.

Please peruse and digest that info again. It took a lot of effort to compile that.

Does it need clarification?

 

I'm a bit confused and trying to replace my pump. Car is a 72 350 w/o A/C. I've never had an issue with pulley alignment to date. I purchased Flowkooler 1776, expecting mine to be a 5.6 pump. It turns out it had a 5.1x1.8 installed. Now, I have a receipt saying the water pump was replaced on 10/13/1983 for $71.12. It is handwritten and includes miscellaneous parts but there is nothing to suggest the pulleys were changed. Casting number on the pump is 384783, which appears to be for a 65-67. Are there any other differences besides length I should be aware of, or will the Flowkooler 1575 work despite the fact it says for 1965-1970? Also, I'm kind of bummed that it's not aluminum like the 1776, does anyone know of an aluminum 5.1 pump?

 

The hose nipple change diameter from 1970 to 1971.
1970-older had 2" and 1971-later had 1.75".

 

If that's the case, I'm having trouble locating any 5.1x1.75 pumps, all are 5.1x2. Does anyone know of one, particularly one in aluminum?

 

What size is the outlet on your radiator? The later cars with 1.75" water pump inlet had 1.5" radiator outlet. The early cars with 2" water pump inlet had 1.75" radiator outlet.

Match your radiator to the hose diameter or you will have to search for some sort of adapter setup.

 

Since it seems the 5.6 pump is far more common and I already have one, can I just change the WP pulley to one for a 5.6 pump? Looks like they align 0.5" closer to the engine.

 

Probably, the trick would be to find said pulley. Reproduction KM should do what you want.

I don't think there is such a thing as the 5.1" pump in AL.