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Water pump cause drive belt alignment problem

1999gmc

1999gmc

Active Member
Messages
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Location
Carmichael, CA
So about 20K miles ago my front cover started leaking a little coolant. I pulled the front cover off, ended up replacing the timing chain, water pump, and drive belt while I was there. Bought a GMB water pump. Have used them in the past on other vehicles and never had a problem. The next oil change looked like the new belt might be fraying on the outer edge a little. Figured I'd keep an eye on it. Here about 5000 miles ago I was getting a belt noise on cold mornings so I checked it again and the belt was frayed pretty good on the outer edge. Warrantied the belt and replaced the tensioner and watched the belt with the engine running. The belt is at the outer lip of the vacuum pump pulley. Shut it off and it stops just inside the lip on the pulley. Put a straight edge on the P/S pulley across the crank pulley and its even/parallel to it. Put it on the vacuum pump pulley and it angles in toward the crank pulley. Touches on the far side/PS side of the crank pulley, and has about a 1/16'-1/8' gap on the vacuum pump pulley side of the crank pulley. Pulled everything off and when I loosened the nuts at the water pump part of the bracket, you watched the bracket pull away from the pump about a 1/8". I still have the old pump sitting on my bench. Mic'd the thickness and the new one is narrower where the bracket goes. I ended up deciding to leave the pump alone and put a 1/8" washer on there, then the bracket. Put a straight edge on the pulley and everything lines up perfect. Fired it up and belt runs right in the middle of the pulley now.

Oh forgot to mention, before I pulled it all apart I pulled the vacuum pump pulley off about a 1/4" to see if that helped. With the engine running it still walked out to the lip of the pulley. So that was telling me the angle of the vacuum pump was off. Hope this helps if anyone else has a similar issue after replacing their water pump.
 
neither. The water pump I put on was thinner than the factory one where the alt./vacuum pump bracket bolts on to it pulling the bracket in when the nuts where tightened. Which pulled the vacuum pump in at an angle throwing the belt alignment off for the vacuum pump.
 
Ah, ok. Duh! Hence bringing up the waterpump. My brain is broken latey. Document it with pics incase you return it for a refund.
 
I am running into similar problems trying to put together a 6.2 with a 1996 6.5 accessory setup. I think my problem though is forgetting/misplacing brackets and spacers since it was back in March when I pulled everything apart. Anyway if the main brackets are bolted straight to the heads, the pulleys will not line up. If anyone had a picture or two of how those brackets mount up, that would be a huge help.
 
You have the engine lift bracket in place?
 
That is what I was worried about.... but with the 96 set up I do not see a place for it. Does it go on the passenger side head by the alternator? The AC bracket (drivers side) has a lift eyelet built in......I found a diagram that showed no spacers or other brackets, but a stud was used where I was trying to use a bolt so I think (fingers crossed) problem solved.
 
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