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!
both pumps.jpgpump diff.jpgbelt clear.jpg
Nice pictures.
Bruce. >:D
Can you get us a couple of measurements across the two throats?
Greg surfas
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.
belt clear on car.jpg
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
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. >:D
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.
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!
Not that it has anything to do with the water pump clearance issue but looking at the photos in #3 the crank pulley looks to be stamped steel, I thought the pre 77 stuff was cast? You can tell by the gap between the front and rear grooves its a non smog which is common (or only option) for a 70. Or was 70 the or one of the years that there was a cast ballancer sort of thing behind the pulley vs the later engines that it was just a hub on the crank? So maybe they felt they didn't need the weight of the cast pulleys? But then changed their minds again for a few years before changing back? By the 425 era I'm sure it was cost and weight, not what was right but I didn't think they were doing that sort of thing as bad in 70.
Again I don't think the pulley type had anything to do with the water pump issue, as far as I know the dual grooves were always in the same position and when they went to a single it too was always the same for this family of engines.
And if anyone is wondering if any of the water pumps for the 472-500-425-368 had a different position for the fan/pulley I believe the answer is and was always no, they were all the same so if you are having issues with your fan or that belt its not because you have the wrong pump.
Got the radiator back and installed today. Just went for a drive, and had no issues with the belts slipping. Tentatively I think that issue is solved, but I reserve judgement for hotter weather. Radiator and hoses are dry, so success on that front so far.
TJ, indeed the pulleys on the crank are stamped steel, not cast. The parts book shows the 1970 balancer as a one year part (#3515077) "Balancer, w/triple pulley". Best I can see, having never had it apart, it appears there is a balancer ring tucked inside the double pulley. Thanks for your insight! The only other Caddy I have owned is my '65, and the only 472 I have had apart was my dad's '68. Needless to say, I have zero memory of what the '68 balancer looked like as that was 40+ years ago and I don't remember what I had for breakfast this morning.... :-)
Happy Motoring!