1970s 70 SDV Water Pump Belt Clearance w/pics

[bctexas]

I replaced the original AC compressor in my '70 SDV with a modern one a couple of years ago.  It has only one belt groove vs two on the factory compressor.  The groove lines up with the inner pulley on the crank.  I discovered that the inner belt had been rubbing on the water pump housing since I got the car.  Research at that point led me to conclude that it was the wrong water pump.  I made do using the inner groove on the PS pump to run the AC, with the outer ps pump groove run by the crank.  I would sometimes stall the pump.

The radiator in my '70 sprung a leak a couple weeks ago and is at the radiator shop for a new core.  I decided it was a good time to fix the water pump issue.  I ordered a Gates 44032 water pump based on an earlier conversation on this forum.  However, that pump was the same casting as the one on my car, so back it went.  I did find what turned out to be the correct pump on Ebay, and it is now installed.  The belt now has clearance.  Here is what you need to look for....

First pic is the two pumps.  You can see the marks on the older one where the belt was rubbing on it.  Second shows the difference in the neck of the water inlet.  Last shows a piece of bar stock laying on the old pump on the wear path, showing the clearance provided by the correct pump. 

The first replacement pump I received was listed on Rock Auto as a replacement for GM part number 3633088.  However I believe this to be incorrect.  3633088 is listed in the '64-'74 parts catalog as all '68 to '72, plus '73 with two groove power steering pump.  I believe the Gates 44032 that I got is the GM part number 3633853, listed for '73 to be used with the single groove power steering pulley.  Now, these are the only two pump castings for a 472/500 that I have ever seen so for all I know there are others out there.  I suspect that which pump casting comes in a rebuilder's box is a crap shoot.

Happy Motoring!

[The Tassie Devil(le)]

Nice pictures. 

Bruce.

["Cadillac Kid" Greg Surfas 15364]

Can you get us a couple of measurements across the two throats?
Greg surfas

[bctexas]

Thanks Bruce!

Greg, the thicker casting is 1 3/16 inch where the belt rubs.  I installed the correct water pump yesterday so measurements are a bit more difficult.  But the casting is about 1 1/32 inch thick at the point where the back of the belt passes by.  Clearance from the belt to the casting is about 3/16 inch.  The pic shows the belt passing the new pump.

Hope this is what you were looking for.

["Cadillac Kid" Greg Surfas 15364]

Yes thanks. I've got a few rebuildable pumps and I know there are a few of the early ones. Now I can determine which are which
Greg Surfas

[The Tassie Devil(le)]

G'day BC,

Are those the correct belts for the pullies?  The reason why I ask is that they seem to be riding way too high in the "V".

Bruce.

PS.   Running too high in the "V" stops the sides of the belts from correctly gripping the sides of the "V", and therefore the belts will wear out faster as the outer portion is not being used, which it was designed for.   BUT, running the belts too low in the "V" runs the risk of the bottom of the belt hitting the bottom of said "V", and then there is less friction, allowing the belt to slip.

[bctexas]

G'Day back atcha Bruce!

That is a Gates 7597 which is the part number Gates shows for the ac/ps belt.  I did notice that too, but I haven't run it yet - radiator isn't back from the re-core job.  I figured I'd give it a chance and see how it works.  If there is a better fitting brand/part number out there I'm all ears...

Happy Motoring!