Water pump belt slipping on A/C big block

[Robert B.]

I'm trying to solve a belt problem on a 67 427/390 air car. Whenever I turn on the A/C system the water pump belt, which drives the A/C compressor via the water pump pulley starts to squeal as the head pressure builds up. I am running a correct new Quanta belt set. Talked to them, and they say they this is the correct belt. This belt is P/N 29-B-085, 32" long and 3/8" width.

Anyone have this problem - and hopefully a solution??

Bob

[John C.]

Re: Water pump belt slipping on A/C big block

Bob

I had the same problem when a bought by 67. It had an incorrect width belt on it. The AC belt should be 15/32 width and not 3/8. Once I changed the width everything was fine. I wasn'using Quanta belts but I'm sure you'll get the same results. I put on a Goodyear Gatorback belt.

John

[Allan J. Wicklund]

Re: Water pump belt slipping on A/C big block

Too much Freon will also cause this. Al W.

[Wayne W.]

Re: Water pump belt slipping on A/C big block

I never pay any attention to the original belt, and fit each one to the application. That belt has no tensioner, like some models, and it is difficult to get one tight enough. I go to the store and get a few belts close and a little shorter. I try them until I find one that will install tightly. I remove the water pump pully and pry it up and on with the belt already installed in the V grouve. This way you can get a good tight fit. That will solve the squealing problem. Remember the modern belts from parts stores are metric and not the same size as originals, so original numbers etc. are useless other than a general guide.

[Robert B.]

Re: Water pump belt slipping on A/C big block

Thanks for the feedback - I'll try a 15/32 width - does anyone happen to know the length that worked on your cars?

Thanks,

Bob