Broken timing belts anyone?

[pstephens46]

Seems as if broken or catastrophic belt failures are rare with
Yamaha 4 strokes. Based on everyone's experience, is this true?

[rodbolt17]

only broken belts I ever saw were either damaged when pulling a flywheel or when a thrust bearing let go.
does not mean they cannot and some engines it will get expensive rapidly.

[boscoe99]

Belts break, chains break and gears break.

Not often fortunately.

Let the debate begin over which cam shaft drive mechanism is the best. It was beat to death recently over on THT. Whomever had motors with a certain type of drive mechanism were trying to shoot down the other types of drive mechanisms.

[rodbolt17]

the old nylon chain and gear sets failed.
the even older inline 4 and 6 GM nylon cam gears failed.

however that is why all manufactures that use timing belts have SERVICE information.
if the use a chain they have TENSIONER service information.
in the case of the 3.3L f200/225 it uses both chain/tensioner and a belt/tensioner.
but Yamaha published data on service/inspection/replacement intravals.
whether the consumer wishs to follow the data is up to the customer.

my work shirts don't have Maytag on them.

[ausnoelm]

None should wear out if the maintenance is performed as specified, a random failure caused by something else can occurr at any time, on any product, chains are usually close to being untouched for the life of the motor.

[zenoahphobic]

None should wear out if the maintenance is performed as specified, a random failure caused by something else can occurr at any time, on any product, chains are usually close to being untouched for the life of the motor.

This was a retrograde step to replace chains with belts atleast from a consumer point of view.
One would like the industry to strive to make every component last the "life" of the engine, instead of creating jobs for people and relegate more and more parts to be replaced at regular intervals.
Of course the industry doesn't care because it adds the backyardigan mistakes by someone trying to reduce costs, to further profits by selling more parts and by the more likely significant resultant engine damage leading to more turnover of new engine sales.

[ausnoelm]

I think belts are common to save weight, a single belt is a lot lighter than chain.

[zenoahphobic]

I think belts are common to save weight, a single belt is a lot lighter than chain.

Yeah the "plastic revolution" to save weight.

[boscoe99]

Belts be quieter too.

Wish we had a list of modern autos and trucks that use belts versus chains. I am guessing that belts outnumber chains by a good margin. But...

[rodbolt17]

typically belts require less maint than chains now.
typically belts require no lubrication. chains do.
typically belts are way quieter.
typically belts are easier to change.
unless its an old Vega, then your gonna pull the water pump to replace the gasket when you adjust the belt.

[boscoe99]

This was a retrograde step to replace chains with belts atleast from a consumer point of view.
One would like the industry to strive to make every component last the "life" of the engine, instead of creating jobs for people and relegate more and more parts to be replaced at regular intervals.
Of course the industry doesn't care because it adds the backyardigan mistakes by someone trying to reduce costs, to further profits by selling more parts and by the more likely significant resultant engine damage leading to more turnover of new engine sales.

On most all of the motors I have ever owned the accessories (water pump, generator, etc.) almost never lasted the life of the motor. If they did then I considered it poor life from the motor.

A cam shaft drive belt on a Yamaha outboard motor is a hellava lot easier to change than the water pump on my wife's car. Now to be fair, changing the pump itself was not a real problem. It was getting to the damn thing that was the problem. Oh, getting to the rear set of spark plugs to remove and replace them was about as problematic. I can't even begin to remember all of the crap that had to be removed to gain access to the plugs.

[zenoahphobic]

On most all of the motors I have ever owned the accessories (water pump, generator, etc.) almost never lasted the life of the motor. If they did then I considered it poor life from the motor.

A cam shaft drive belt on a Yamaha outboard motor is a hellava lot easier to change than the water pump on my wife's car. Now to be fair, changing the pump itself was not a real problem. It was getting to the damn thing that was the problem. Oh, getting to the rear set of spark plugs to remove and replace them was about as problematic. I can't even begin to remember all of the crap that had to be removed to gain access to the plugs.

I guess meaning to "life of the engine" has changed over the years, and to be fair cars are far more complicated because of all the extras demanded today.

I remember cars that didn't have heaters, radios, aircon, power steering, electric windows, mirrors, indicators, reversing lights, power steering, automatic transmission, more than three manual gears, starter motor, electric wipers (vacumm driven), tacho, gauges(just odd light).... and the list goes on.

Similarly engines required little maintenance (atleast fewer procedures), however did not last as long as engines of today. Engines were totally rebuilt or exchanged. Rebores, new rings and valve grinds commonplace. Today to the ordinary car owner, this appears non existent. Even sparkplugs seem to last much longer. Oil always looks clean too.

We are not arguing that Yamaha engines are more difficult to work on than cars, to the contrary, most of the engine is right there at working height infront of you. A simple radiator replacement in a car (that seems to be on the list of regular replacement parts now), tends to require substantial dismembering of the front of the car. To be fair the tooth belt is far superior to V belts. I remember V belts failing and having to spend a lot of time adjusting and replacing them; not so now.

Finding spark plugs or even recognising what is under a modern bonnet involves dedication, so I empathise with todays disinterest in the workings of a car. But I don't understand why this leads to a blatant neglect of important checks, no matter how many times I say it, no one in my family even checks tire pressures!

[99yam40]

I guess meaning to "life of the engine" has changed over the years, and to be fair cars are far more complicated because of all the extras demanded today.

I remember cars that didn't have heaters, radios, aircon, power steering, electric windows, mirrors, indicators, reversing lights, power steering, automatic transmission, more than three manual gears, starter motor, electric wipers (vacumm driven), tacho, gauges(just odd light).... and the list goes on.

Similarly engines required little maintenance (atleast fewer procedures), however did not last as long as engines of today. Engines were totally rebuilt or exchanged. Rebores, new rings and valve grinds commonplace. Today to the ordinary car owner, this appears non existent. Even sparkplugs seem to last much longer. Oil always looks clean too.

We are not arguing that Yamaha engines are more difficult to work on than cars, to the contrary, most of the engine is right there at working height infront of you. A simple radiator replacement in a car (that seems to be on the list of regular replacement parts now), tends to require substantial dismembering of the front of the car. To be fair the tooth belt is far superior to V belts. I remember V belts failing and having to spend a lot of time adjusting and replacing them; not so now.

Finding spark plugs or even recognising what is under a modern bonnet involves dedication, so I empathise with todays disinterest in the workings of a car. But I don't understand why this leads to a blatant neglect of important checks, no matter how many times I say it, no one in my family even checks tire pressures!

Or the oil and water levels it seems.
Makes for good vehicle sales or parts sales and mechanics jobs

[ausnoelm]

I tend to agree cars are much better now than years ago, most modern cars you can just get in and drive away for your (say) annual holidays, many years ago, taking a car on a long trip was a "mission" the car would need to be checked and fooled around with, and probably would encounter some drama during the trip, outboards are the same, launch the boat, turn the key and you're gone, many years ago, it was pump the primer, lift the lever to some exact spot, push in the choke, turn the key...and hope, if it did start, you would fiddle with the choke on and off to keep it running, after the smoke cleared, sometimes you could idle away, most times, it was a restart.