Yanmar 4jh3e belt problem

[Valerio]

Hi to all sailor, my yanmar keep eating belt, there is a similar tread here, i have try to clean the pulley, mark the alternator braket to see if is it moving, but the same problem stay. There is a vibration of the belt between the cranshaft pulley and the water pump pulley, but between the water pump and the alternator there is not. I need to change belt every 10 hours...
What belt brand number are you using?
Any help very welcome

 

[SEMPERAVANTI41]

Gates green stripe

 

[Valerio]

Please tell me the gates number

 

[sailcapt340]

Valerio,
How tight are you installing your belts? Rule of thumb has been 1/2 inch of play on the belt.
I ask because you say there is "vibration" in one belt and not the other. Which leads me to think one is way to tight and the other is way to loose.
Are there any burrs on the pulleys that can could cause premature wear like that?
10 hour replacement, if they are the proper belts, is excessive even for a sailboat.
Hope this helps.

 

[Valerio]

Vibration is on the same belt, this engine has only one belt.

 

[sailcapt340]

Valerio,
Can you post some pictures. That would go a long way for help from others.

 

[Michael Davis]

Something very wrong there. Alinement, tension? But something. My current belt has over 700 hrs on it without much wear. Shouldn't need to change the one in your boat more often than the one in your car.

 

[Terry Cox]

My current belt has over 700 hrs on it without much wear.

Ditto here Valerio. Our 4JH2-TE has the same belt as when we purchased her in 2002. It remains in good condition and has more than 700 hours on it. Something is causing the belt to fail in such a short time. Misalignment could be a cause or maybe check the two appliance pulleys; sea water pump and alternator. Do they turn freely? Remove the belt and check for any resistance to turn. A burr in the pulley could do it as well. A puzzle for sure.

 

[Michael Davis]

@Valerio have you changed to a high output alternator? Overloading the belt is another cause of high wear. If you think the bracket is backing off you might check " making alternator belt tension easy"under engines and propulsion. Several good ideas there. Check alt. and pump as per @Terry Cox .

 

[DayDreamer41]

@Valerio how long have you had your boat? How long have you had this belt issue? Is it the previous owner upgraded the alternator size and not the way its being driven? Even the stock 80 alternator would benefit from a serpentine belt system, but anything greater than an 80 alternator needs to have a better drive system such as the serpentine pulleys and belt. Other issues are as suggested, alignment in both pulley to pulley and pulley being set on the same plane as the belt (perpendicular to the drive plane)

 

[Don Lucas]

I replaced my belt last on my 4JH3E with 100 amp alternator last month. The belt I replaced lasted 530 hours and was an OEM belt. The one prior to that was also an OEM belt lasted years and over 1000 hours. I currently have a Gates "green" belt and will see.

Any 1/2'x46/47"belt should work.

Check your pulleys for rust and pits in the grooves. Alignment of course is a issue, but doubtful yours suddenly goes out of alignment.

 

[ice breaker]

Get a toothed belt, they wear better and do not produce the black dust.

 

[Valerio]

Since i get my used boat there was black power around the engine. I do not know if the alternator is high output.it look original. I have cleaned the pulley with sand paper and look if the pulley are alined and they are. If i am correct if there is dust the belt must be slipping. I am on my second belt in less than 200 hrs. The belt will start to slip and will get hotter and will slip more, iwill try to put some anty slip on the belt.

 

[Michael Davis]

Proper tension is way better than "Spray Grip".

 

[sailme88]

Alignment... sounds like a shim is needed. You can use a framing square to verify alignment. With belt removed use the square to prove or disprove alignment. Most times it's the alternator pulley that is the culprit. Shim the pulley, don't try to tweak the mount.

 

[TomY]

If your alternator is a high output, are you asking a lot from it? Meaning is the alternator working overtime due to loads your boat is using?

If so maybe look into ways to cut the alternators output back, until you figure out alternatives.

 

[Valerio]

If your alternator is a high output, are you asking a lot from it? Meaning is the alternator working overtime due to loads your boat is using?

If so maybe look into ways to cut the alternators output back, until you figure out alternatives.

I have changed my battery set up, now i have almost the double amps of what i had, is it possible that my alternator now is putting more stress on the belt?

 

[Michael Davis]

Changing your batteries doesn't change the stress on the belt. A higher output alternator would, a bearing going in your alternator or in your water pump would add load to your belt too. Adding to your batteries may require a larger alternator ( maybe) or just more engine hours. Alinement, tension and bearings would be the big things if your alt. isn't too big for the belt to start with.

 

[Mike Oldak]

Michael is right. I believe that doubling the output, under full load, will require about twice the torque, and thus friction between the belt and pulley. If you have shore power when in port, the batteries shouldn't be drawing that much current.

One thing to ty is to remove the belt and turn your alternator and water pump pulleys should turn relatively easily.

 

[Mike Oldak]

I have cleaned the pulley with sand paper

I read some of the prior posts and noticed this. The pulleys need to be perfectly smooth, sanding them may turn them into rotating files.