Water pump pulley self destructed-HELP!

[dr.delco]

Hi everyone,
I was wondering if anyone has experienced this or had it happen to them.
We're talking about a 64 truck with a stock 230 inline 6. Today my water pump pulley decided to separate itself from the water pump shaft. The water pump shaft spins easily, I do not believe it locked up. I have had many old cars and trucks and have never seen this happen. Any ideas as to the cause? Metal fatigue on a 50yr old pulley? Also, does anyone know what would be a good replacement for this pulley. Inline 230's are not that plentiful in the boneyards. It measures 7 1/8 in diameter. Thanks

[RANDY COX]

WOW never saw that b4 either, I guess it could of had a hairline crack that finally give up.
Hopefully you can find one on the parts board, I would think they would be plentiful. As there were prolly more six's than 8's..

[AcampoDave]

It's happened to me before on a 283. The pully wasn't quite as torn up as yours but I also had no obvious explanation. Got myself a Chinese made chrome one at Napa, painted it black and it's been good, for many miles now. Napa counter guy asked me if I was over tightening the belt but I didn't really think so.

[63burban]

For this reason they installed a re reinforcement plate on the hub of the water pump. Check to make sure your water pump bearings are good and a new belt. Do not over tighten.

[Captainfab]

I may be wrong but I was thinking that the small block short water pump pulley is the same as the I6 water pump pulley. That might be something to check into.

[Old Truck Man]

yes there is a reinforcement plate washer whatever on many. Metal fatigue. after a certain amount of time metal wears out and cracks. the old semi trucks it used to set in at about a million miles hairline cracks would begin to appear around rivets & bolt holes. leaf springs would break. With the air ride suspension & radial tires they last longer today. There are harmonics at work that fatigue out things like water pump & alternator bushings & bearings. The fan belts & pulleys are not in perfect balance. That water pump pulley is a stamped and formed part. metal is stretched and forced to take a unnatural shape. Having the belt groove so far from the center line of the hub is poor engineering. Its a wonder that it works,

[dr.delco]

Originally Posted by Captainfab

I may be wrong but I was thinking that the small block short water pump pulley is the same as the I6 water pump pulley. That might be something to check into.

If my research (OE parts books) is correct, I'm finding that PN 3905995 should be the correct number for my truck's 230. Would this also be the short water pump single groove pulley used on many 1960's small blocks?

Unfortunately, I looked on my pulley and cannot find a stamping with a part number.

[Dillon Rock]

Mine did the same and hairline cracked. Got a new one off of a 283 v8 same and all and put a pulley spacer shine behind it and worked. Mine had a washer to space it off the hub to keep it from rubbing against the water pump bypass hose and that's what cracked the old one. Too small a shim will put pressure on the shims area and do that. I have a 292 so it was fun to hear it scrape against the harmonic balancer and leave a nice Shiney line on the back of it not to mention see coolant spitting out under pressure when it finally went through the bypass line.

[1963c-10]

Originally Posted by dr.delco

If my research (OE parts books) is correct, I'm finding that PN 3905995 should be the correct number for my truck's 230. Would this also be the short water pump single groove pulley used on many 1960's small blocks?

Unfortunately, I looked on my pulley and cannot find a stamping with a part number.

I believe I have one in the back of my parts truck. Let me look tonight. You can have it for shipping if its still there.