Alternator/water pump belt keep burning off

[MacinTek]

Yes, I've tried spinning both water pump (>10 years old) and alternator (< 2years old). Both spin as they should. Yet, I install a new belt and tension it so it doesn't slip or strain, and, within a quarter mile, I see smoke rising from the engine bay and the alternator light comes on... sure enough, belt is gone.

What else should I be looking for?

[SamHill]

Yes, I've tried spinning both water pump (>10 years old) and alternator (< 2years old). Both spin as they should. Yet, I install a new belt and tension it so it doesn't slip or strain, and, within a quarter mile, I see smoke rising from the engine bay and the alternator light comes on... sure enough, belt is gone.

What else should I be looking for?

Reinstall belt. Tension as needed. Take a piece of string, holding one end, and let it fall toward the ground. Move the string toward the middle of the belt. Is the top of the belt aligned with the bottom?

[DMC-81]

Some things to check:

1) The alignment of the water pump/alternator/crank pulley to ensure they are all flush and not cocked out of alignment ( especially the alternator)

2) Is the water pump stock? Sometimes a non-stock water pump pulley makes the alignment off.

3) Is the alternator /pulley / bracket stock ?

4) Is there anything close to or actually interfering with the belt ( e.g. A different bracket or shield etc)?

5) Re-check the tension. (As mentioned above^). It doesn't need as much as one might think.

[Jonathan]

What make and model of belt are you using and where did you get it (them)?

[dmcnc]

If you could also share pictures of your set-up that would be helpful.

[David T]

Inspect the weep hole on the bottom of the neck of the water pump. If you see any staining replace the water pump. Make sure the alternator is lined up with the other pulleys. Don't overtighten the belt.

[Andrew]

Make sure the large alternator bolt is not over-tightened. I had a similar problem and the upper bolt turned out to be the culpret. I backed off the bolt slightly and the problem was resolved.

[DMCMW Dave]

Some things to check:

1) The alignment of the water pump/alternator/crank pulley to ensure they are all flush and not cocked out of alignment ( especially the alternator)

This one. You probably have the spacers screwed up on the alternator mount. What alternator is it? Stand to the side of the car and sight along the belt and the two pulleys. Also look straight down - a water pump with an improperly installed pulley will do this. Make sure it matches up with the crank pulley.

Too loose is worse that too tight BTW. If too loose it will slip.

[Blackie]

I had a similar issue many years ago. The water pump pulley is the press on type and had started to back off the shaft. The shaft has an internal thread, i used a long socket and a bolt to press it back on, then had a spacer machined up to keep on there permanently to keep it from backing off again.

[TGGreene]

Yes, I've tried spinning both water pump (>10 years old) and alternator (< 2years old). Both spin as they should. Yet, I install a new belt and tension it so it doesn't slip or strain, and, within a quarter mile, I see smoke rising from the engine bay and the alternator light comes on... sure enough, belt is gone.

What else should I be looking for?

The stock muffler is about an inch from the lower pulley and belt. That muffler gets seriously hot seriously fast. Is the factory heat shield betweent the muffler and the pully/belt still there? Mine had been broken. I made a new one out of a sheet of metal reinforced exhaust gasket material that I bought from NAPA. Cheap, looks pretty much factory, and and works perfectly.