Belt Smoke

[Astroboy]

Hi Everyone,

I am a new owner of a 1999 Pro Air Nautique. It has a Ford GT-40 motor. I have recently replaced the alternator belt (previous owner had a 'v-notch' type belt installed). The original belt would squeel on start for 5-10 seconds (basically until it warmed up). I replaced it with a new OEM PCM belt and had absolutely no noise or problems... until yesterday.

We were on the lake at 6am, had 5 boarders/skiers ride for about 1.5 hours without problem. Then, we sat for about 10 minutes to drain the ballast tank before heading to the docks. The engine didn't start on first crank (it usually does - this time took about 10 cranks before it turned over), then as we were heading back around 25mph - I smelt something burning. Took the boat back to idle and noticed smoke coming from the engine compartment. Opened the cover and only minor amounts of smoke but it appeared to be coming from the alternator belt. It was physically hotter than the water pump belt and I noticed the paint on the alternator pully has come off. I waited a couple minutes, then decided to try starting the engine with the cover up to see if I could tell what was happening. Started great and no issues... no slipping or anything... no problems the rest of the way back to the dock...

Any ideas? Is the belt too tight or too loose? I'm thinking maybe the alternator is having issues and giving it time to cool down it seized up? Might try to take the belt off before running next time and see if the alternator spins freely. Is there anything else I should be looking for? Thank you for any help or suggestions.

[TravisFling]

RE: Belt Smoke

That's odd, I've never had that happen. The smoke must have been relatively prevalent to have smelled it while underway. I would certainly check the alternator out, if you believe that to be the spot where the smoke was coming from. It may have locked up and the belt was spinning around the pulley, causing the friction. If that is the culprit I'd replace that belt again once you get it fixed.

[AirTool]

RE: Belt Smoke

Could you have the new belt too tight?

Why did you replace the v-notch?

[Astroboy]

RE: Belt Smoke

I haven't been back to the boat since my last post. It is possible that the belt is too tight... but I don't know. It was pretty hard to get it on the pulleys to begin with! the belt should deflect 1/4", correct?

I replaced the v-notch because the belt was squeeling... we just thought we would try the OEM part to see if that fixed the problem and it appeared to... but now it seems that I have another problem. I will update this thread once I run the boat again.

[AirTool]

RE: Belt Smoke

the belt should deflect 1/4", correct?

That would be good. Check all the bearings and pulleys while you're at it.

[Astroboy]

RE: Belt Smoke

Would you be able to elaborate on what to check for on the pulleys and how to check all the bearings? Thank you!

[AirTool]

RE: Belt Smoke

Check that the pulley faces are smooth, not rusted, etc and that they line up in the same plane. You can use a straight edge, or string, etc.

Get the belts off and spin the alternator and water pump by hand. They should spin fairly freely and feel smooth. There should be no growling, play, slop, whatever. Nothing should wobble either.

[jpduster]

RE: Belt Smoke

The higher the electrical load placed on an alternator the harder it is to turn. Could you have been overrunning your electrical supply?
ie. pumping and listening to loud tunes etc while at idle possibly causing some slippage or adding to slippage.

[Astroboy]

RE: Belt Smoke

Okay, so I was at the boat last night to check a few things out. Belt tension seemed fine, so I took the belt off to check if the alternator was spinning freely. The alternator seems to spin fine, no problems. I fired the engine without the alternator belt in place and also with a couple electrical devices running (stereo, blower, ballast pumps) to try and load the electrical, alternator spun by hand no problem. I put the belt back on and fired it up. Absolutely no issues. Voltmeter looks good... Ran the boat for a bit last night... a couple easy starts and stops. Again ran this morning (gotta love riding before work!), 5 different skiers/boarders, absolutely no issues with the belt or anything else...

So... as of now, it seems that the smoking belt was a one time issue... tough to troubleshoot something when you can't reproduce it.

Thank you for everyones help and suggestions, hopefully the problem won't come up again! I'm definitely keeping a spare on board though!!

[AirTool]

RE: Belt Smoke

Maybe it was just the slippery new rubber or there was some kind of coating on it left over from manufacturing.

How many belts are there? Does the alt belt go around the water pump also or driven just by the crank?

[Astroboy]

RE: Belt Smoke

It's a GT-40 which has 2 belts. One for the water pump and one for the alternator.

I'll just have to keep an eye on it... hopefully it was just some funny new belt quirk.

[elwood]

We've got a 99 Pro Air too, with the same motor. We put a new belt set on last year, and had smoke from the alternator belt. That belt shortly shredded. We put a 2nd new belt on and the same thing happened. Put the old belt back on and no smoke, no shredding. We could see that the alternator pulley was out of alignment, but the brackets that hold the alternator in place are stout and unlikely to distort, so it is hard to imagine how it was ever right, or maybe the previous owner replaced the original alternator with a wrong one. Last night we were driving around and volts were low, the belt had shredded again. We put 2 washers underneath the alternator bracket where it mounts to the engine, and the alignment now is correct. Now we will try a new belt and see how it works.

BTW, anyone know what size that alternator belt is? I don't have CC dealership near, and I know it is probably just an A section belt of a standard length that I could get from Autozone.

[DanielC]

Question one, how old is your battery?
The alternator does not load the engine at cranking speeds. You cannot spin it by hand, fast enough to have it generate any electricity to load it.
After your engine starts, then the alternator makes electricity to charge the battery, and it puts out its max amperage for a short while. This is the load that causes your belt to squeal sometimes. If you hear this squeal, your belt is too loose, or worn, or both. You need to tighten the belt a little, and maybe replace it with a new one.
You really need a belt tension gauge to set the belt correctly. How hard are you pushing on the belt? I do not know. Push hard enough on a correctly tensioned belt, and it will appear loose. Push not hard enough, and a loose belt will appear tight, and squeal, and wear itself out quickly.
The waterpump belt on a GT-40 does not need to be as tight as the alternator belt.
If your battery is used to power stereos, amps, while sitting, that will discharge your battery more than normal, and the alternator will have to work at full charge longer to fully recharge the battery. This is also a problem on moored boats that have the bilge pump on, and sit too long.
Your belt was probably a little loose, and worn. After draining your tanks, and sitting a little while, and then having a little difficulty starting the boat, the battery wanted a lot of electricity to recharge. Your alternator was working hard, for a long time, and the worn belt was slipping, and finished wearing itself out.
Go to a site sponsor and buy a spare belt kit for your motor. It is not that expensive. In an emergency situation, you can also use belts form any auto parts store, that fits. Sorry, I do not have the NAPA numbers.

[NCH2oSki]

When I changed belts on my GT-40 this spring I noticed the Water Pump was not in alignment. I ended up shimming it to get it into alignment, and as you mentioned the brackets are straight and not distorted in any way. I ordered a spare belt to keep just in case, I had a lot of belt dust before the shimming.

[DanielC]

If you have to shim the water pump to align the pulleys, there is a good chance you are putting too much tension on the water pump belt. This can cause the bearings in the water pump to fail.
Check the surface of the pulleys. If there is rust on them, or they are not smooth, it acts just like sandpaper, and grinds the surface of the belt, creating the dust.