Alternator belt keeps falling off - Bad Harmonic Balancer?

pregler

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I have a 92 Caravelle 1750 BR - with a 3.0L/LX Mercruiser engine. and it ran fine the first few times I took it out on the lake. Recently I took it out onto a bigger lake here in Minnesota, and I was driving along when I noticed the power steering stopped working and i was at 11-12 volts instead of the regular 14 volts I normally run at.

When I got to the dock I checked and sure enough the belt had fallen off of the ALT which meant it wasn't spinning the power steering pump.

This happened several more times when i brought it to the next lake. If i look in the boat it looks like there is a lot of rubber dust from a belt getting worn down.

The picture below is a close of of the harmonic balancer, it shows where the two metal parts meet the rubber part. they look pretty far off to me. Is this causing my issues?

If so has anyone had bad luck with the one people are selling on ebay for $126.00? I would greatly like to save $175 and not buy OEM. But i understand OEM can mean quality as well.

PLEASE HELP!
 

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alldodge

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I have a 92 Caravelle 1750 BR - with a 3.0L/LX Mercruiser engine. and it ran fine the first few times I took it out on the lake. Recently I took it out onto a bigger lake here in Minnesota, and I was driving along when I noticed the power steering stopped working and i was at 11-12 volts instead of the regular 14 volts I normally run at.

When I got to the dock I checked and sure enough the belt had fallen off of the ALT which meant it wasn't spinning the power steering pump.

This happened several more times when i brought it to the next lake. If i look in the boat it looks like there is a lot of rubber dust from a belt getting worn down.

The picture below is a close of of the harmonic balancer, it shows where the two metal parts meet the rubber part. they look pretty far off to me. Is this causing my issues?

If so has anyone had bad luck with the one people are selling on ebay for $126.00? I would greatly like to save $175 and not buy OEM. But i understand OEM can mean quality as well.

PLEASE HELP!

I'm not sure the balancer is the issue.
fetch


It doesn't really look like it has moved. If you do need one check out your GM dealer, Merc doesn't make the thing, they only add black paint and jack up the price. First thing I would check is make sure all your brackets holding the PS pump and alternator are there and all bolts are tight. Next get a straight edge and place it on the face of the different pulleys and see which one is out of alignment
 

H20Rat

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check your PS and alternator bearings. I've seen them go where they let the shaft walk out a little ways but still are good enough to turn.
 

pregler

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Any idea of what the GM part number is? I haven't had much luck with finding anything besides the Mercruiser part numbers... 8M0086946/55045T/3852662 - Or what vehicle it would be on?
 

pregler

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check your PS and alternator bearings. I've seen them go where they let the shaft walk out a little ways but still are good enough to turn.


To do this I remove the belt and try to move the pully in and out to see if it moves??
 

thumpar

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Also use a straight edge to make sure all the pulleys are in line with each other.
 

Watermann

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Rather than just putting that belt back on, take it off as it looks pretty badly worn out in the pic and you didn't say you tried a new belt. Take the old belt with you and buy the best quality the parts house has.
 

Starcraft5834

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I'm not sure the balancer is the issue.
fetch


It doesn't really look like it has moved. If you do need one check out your GM dealer, Merc doesn't make the thing, they only add black paint and jack up the price. First thing I would check is make sure all your brackets holding the PS pump and alternator are there and all bolts are tight. Next get a straight edge and place it on the face of the different pulleys and see which one is out of alignment


I would agree with Dodge.... brackets loose? broken? I have a 3.0 and found I constantly had to be tightening down the same belt to alternator. Upon closer inspection, I found the slider bracket was cracked... lots of vibration, it happens....the lower bolt was loose too.... back to good as new new...
 

gm280

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Not sure on you setup, but if there are any idler pulleys, I would most certainly check the bearings. See if everywhere the belt rides is smooth to spin. Obviously the harmonic balancer can't be checked that way, but everything else should be able to spin freely. Even your alternator can have a bad bearing and cause issues... Because if you are seeing rubber dust (for lack of a better word) something is dragging the belt and chewing it up making it larger as it eats it and then it comes off...
 

pregler

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Man, you guys have been extremely quick and helpful! I'll go home tonight, remove the belts, check all pulleys/bearings, replace belts and whatever else is needed and hit the lake to see what happens.

Glad I checked here before ordering a new harmonic balancer, as everything that has been listed - is cheaper and easier than that.

On topic - but slightly off, when I remove the spacer on the motor mount, I've seen some people say you need to support the motor (scissor jack/wood blocks), and I've heard some people say the other side will support it just fine. - any input on this?

Thanks,
 

alldodge

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On topic - but slightly off, when I remove the spacer on the motor mount, I've seen some people say you need to support the motor (scissor jack/wood blocks), and I've heard some people say the other side will support it just fine. - any input on this?

Thanks,

Yes support the engine when removing the mount, scissor and screw jacks are best. You should also recheck engine alignment afterwards, it probably will not move but there is always a chance
 

DaboatnutinWA

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I had a similar issue with mine but Im running the 4.3L V6. My pulleys are fine but the bolt on the alternator wasn't tight enough so when I replaced the belt (noticed I had rubber crud all over the alt) I went to my local O'Reilly's and bought the Gates ribbed V belts for better traction as the Mercruiser belts were considerably thinner (And 3X as expensive). Haven't had any issues since. Best of luck.
 

UncleWillie

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Man, you guys have been extremely quick and helpful! I'll go home tonight, remove the belts, check all pulleys/bearings, replace belts and whatever else is needed and hit the lake to see what happens...

Push, Pull, Twist and Rock any item that the belt rides on.
They should all rotate with relative ease. Any motion, other than rotation, is highly suspect.

Rather than hitting the lake, run it on muffs with the engine cover open. Look for any unusual motions.
If it going to throw the belt, it will do it in a big hurry.
 

pregler

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Yes support the engine when removing the mount, scissor and screw jacks are best. You should also recheck engine alignment afterwards, it probably will not move but there is always a chance

How do I Re-check engine alignment?

Thanks
 

Watermann

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If you have a garage to back the boat into you could put a chain on the front lift eye to keep the motor from dropping on that side.
 

pregler

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Just a quick update to this post -

I ended up going to Napa and getting a replacement belt for the alternator - I got the best (I think only one they sell), and replaced the belt. While I had the motor mount spacer off, I bought an extra belt and zip tied off to the side so if the new one breaks - or just needs to be replaced, I can easily do it - without tearing out my back seats to get the dang engine mount bolts out. I also took a wire brush to all of the pulleys to get as much rust as possible off. Since then it has ran like a champ - probably a good 6 hours of run time and not one problem.

Thank you to everyone that told me to not to replace the harmonic balancer and to try replacing the belts first!! Saved me a LOT of time and money!
 

alldodge

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Hope it stays that way, thanks for following up on the thread and closing it. Happy boating
 

fishrdan

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Yup, the rusted pulleys were eating up the belt(s), but they are going to rust again.......... 1- Sand all the rusted pulley grooves. 2- Paint the grooves with a couple coats of Rustoleum paint and let it dry for a couple of days (so the paint hardens). 3- Install a new belt. 4- Enjoy boat!
 
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