Broken down....again

Wrong belts or a belt tension issue I would imagine.

 

What makes you say that? They have bearings, right? Bearings can go bad for a lot of reasons.

Does it feel silky smooth when you spin it? Nice and quiet?

 

In addition to what Steve mentioned I would check the alignment as well meaning there is no wobbling noted with rotation (bearing issue). I would initially suspect tension since nothing appears to be seized.

 

+1
Make sure the bolt is tight enough as I have seen some loose their tension and put on a new lock washer.

Just a side note on alternators, either they can seize up or I have had a couple in my shop faking it. Since yours ran fine I would doubt the alt bearings failed.

 

Which belt is it? At least on my 328 and I assume whatever you have they are different belts.

That would be the first important bit of info.

Did you rebuild the water pump?

 

Years ago I had this problem with the belts melting on my '83. My water pump felt perfectly fine with no belt on it, so I put on a new belt and it melted it again. Turned out to be the water pump, it always felt fine but it was either intermittent or it needed the tension on it to be a problem. After the water pump was fixed I had no problem. But since you did the water pump who knows. I know what you mean about alternators, it seems they usually fail electrically as opposed to seizing up, but it certainly seems possible.
Unless you had it crazy tight, I would not think it would be a tension issue. I don't think it would generate that kind of heat.

 

I had an alternator sieze up once. I'm the only person I know to have this happen and I got months of warning with a lot of bearing noise. Japanese car.

If you can get close to these pulleys look to see if one has more melted rubber on it. I would thing if one is siezing it would have some transferrence.

 

I experienced this problem a few years ago on my '79. There were 2 issues that needed to be addressed. The pivot nut & bolt holding the alternator wasn't tightened & the alignment was off causing the squeak. The threads were stripped. Also the belt was oversize, as there was no room left on the alternator bracket to adjust the tension further. After purchasing the correct belt (smaller diameter) there was lots of room for tightening the belt. New nut, bolt & lock washers & loctite on the main pivot bolt. No problems since & 5000 miles later. I tightened that belt up with as little play as possible.

 

Yep. Polyflex belts are really misleading. They can take a lot of tension, and need it. Personally, I'd pick up a complete water pump from Superformance. Good price and one less thing to worry about.....get it in there with a new belt and hit the road.

 

There are several choices --

new pump from (insert supplier name here)

rebuild at home

rebuild from (insert favorite rebuilder here).

Many folk have bantered names about, and pretty much every piece of feedback I've seen on Fchat about water pump rebuilds has been positive.

I had mine done by Dave Helms at Scuderia Rampante in Boulder CO. Turnaround was quick. The work sure looks great. I sent him the pump AND the housing it connects to. He fixed pitting in the hose connections, replaced a couple of sketchy smaller connection with gorgeous brass hose barbed pipe, faced the mate-up area between the housing and the pump, and made sure it was rebuilt properly. Top quality work sure seems to come out of that shop.

Depending on which pump you have, there are options as to bearing size and (I think) seals.

Research and plan carefully, but you already know how upsetting a leaky water pump can be!

Jonathan
Denver, CO

 

The Dutchman did mine back in 2003 and it's still doing fine. Oh 25,000 miles on it.

 

This statement implies a single belt QV. The water pump and alternator are driven from the same belt. Gate 7m1000 Polyflex

And this is both great advice and the direction you'd best follow. The correct tension is far higher than you're used to seeing, particularly if you haven't worked with the Polyfelx belts before. The WSM and the OM list the belt tension recommended. Also, specifically applicable to the single bet set-up, it would be wise to inspect the alternator mounting bushings. Over time, due to oil leakage in that area and heat, they deteriorate...and can cause the alternator to become off-axis due to the (high) belt tension. These bushings are NLA from Ferrari, but we do make a run these from time to time, as demand warrants.

 

Great tip, thank you. I'll be sure to have a look at those.

 

David, should the Polyflex belts be tensioned to OEM specs or do I go higher? If higher, by how much? I'm about to do this with my new belts - 7M1000 and 11M850 (Sanden conversion) and can check tension with the cricket tool I have.

 

I know you'll cringe when I say this, but I've done so many of them, I often do it "by feel." So, to best answer your question, particularly on the 7m belt, I'd be at the very high end of the factory spec given. If you go too tight, you always run the risk of taking out the water pump bearings...As a guideline, when it's all said and done, deflection on the longest section of the 7m belt will be no more than 5-6 mm, with thumb pressure.

The AC belt, I suspect due to the greater contact area, seems to be less sensitive to tightness. Again, I would still defer to the factory specs.

 

My QV OM says 84-99 lbs for the 7M (for an old belt 68-84) and 50 lbs for the 11M new (42 lbs old). Do these sound typical?