Timing Belt Tensioner Question

[mdunn]

Have 2001 F115 Yamaha and am getting set to change the timing belt.
Wondering about the purpose of that spring that goes from the tensioner bracket to the cowling bracket.
It's certainly not strong enough to provide the tension needed on the belt and besides the bolt that mounts the tensioner doesn't allow for the adjustment bracket to move when it's tightened. The bolt does not have a shoulder that bottoms out before the tensioner is tight like you'd think would be done if you wanted "auotomatic" tensioning.
My Seloc manual just says most larger motors have a spring that maintains the correct tension and I can't find anything specific in the service manual. Thanks

 

[rodbolt]

Re: Timing Belt Tensioner Question

ditch the seloc, it doesnt even make good outhouse paper.
buy the correct Yamaha manual.
turn the flywheel so all the timing marks on the cam sprockets and flywheel line up with the marks on the castings.
its in the yamaha manual.
then remove the tensioner and flywheel.
replace the belt, install the tensioner and flywheel.
while holding a bit of tension in a clockwise direction ,this should slack the tensioner side of the belt, tighten the tensioner bolt to the correct torque. thats about all there is to it. the F115 does NOT use an automatic tensioner like some of the larger F motors.
it needs periodic maint just like the real service manual shows in section 3.

 

[mdunn]

Re: Timing Belt Tensioner Question

Thank you Rodbolt. I do have the Yamaha Service manual as well. That spring on the tensioner kind of threw me though wondering what it's purpuse was.

 

[rodbolt]

Re: Timing Belt Tensioner Question

the spring is for correct tension, while holding a mild clockwise tension on the flywheel, loosen the tensioner lock bolt, the spring will move the tensioner into the now slack side of the belt, retorque the tensioner bolt.

 

[mdunn]

Re: Timing Belt Tensioner Question

I did try that and I thought the belt was way too sloppy.
Might re-inforce the need to change the belt. I ordreed one from the local Yammy dealer and it's supposed to be in Monday.
Pushing on the belt in the middle on the opposite side from the idler it was deflecting about an inch.
I've looked in the service manual and not seen what it should be.
Thanks again.

 

[rodbolt]

Re: Timing Belt Tensioner Question

you MUST properly take the slack from the belt, the tensioner cannot.
last thing to do is to almost rotate the flywheel in a clockwise direction, this will tighten the belt on the port side and slack it on the tensioner side, any other method is at best a waste of time, at worst a disaster in the making.
the F115 is an interference or a non-clearence motor. let the cam/crank relationship get out and you will post about pistons kissing valves and the unhappy relationship that love story is.

 

[mdunn]

Re: Timing Belt Tensioner Question

Ok. I see what you are saying and it makes perfect sense.
Thanks again.

 

[rodbolt]

Re: Timing Belt Tensioner Question

no worries, its not explained very well in most manuals. however the slack must be taken out almost to the point of rotating the engine before final torque of the tensioner lock bolt.
I dont think there is a deflection spec in the manual but memory may just be failing again.
once you do one and stay a night in a holiday inn it just becomes part of routine service to loosen the adjuster,take out the slack and retorque the bolt.
its a 200 hour or once yearly maint action.

 

[jevery]

Re: Timing Belt Tensioner Question

Is this something that needs periodic adjustment on the F150 as well? Or does it have an automatic tensioner? I don't recall seeing anything about periodic adjustment, only replacement.

 

[rodbolt]

Re: Timing Belt Tensioner Question

out of memory, on a sunday night I cant say. I think the F150 has an automatic tensioner that needs periodic inspection, if I think about it I will look at mine this week.
if the tensioner has a spring from the idler to a bracket its NOT self adjusting.