timing belt tension

I have a pretty standard timing belt setup; two gears, a water pump, and a
tensioner/idler. I was talking to someone and timing belts came up. I
mentioned that after replacing my timing belt, if I stood near the belt and had
someone hit the gas, I could hear a faint "whorling" from under the timing
cover that I didn't recognize from before. I have an idea what a too-tight
timing belt sounds like, and thought that I may have gotten it on a little
tight, but nothing too serious because of the low volume of the noise. Well,
this fellow disagreed and said that any noise coming from that area was the
bearings under stress, and thus a timing belt that is on even a little too
tight is going to shorten the life of the camshaft and water pump bearings as
well as the timing belt.

Is he right? Are the bearings the source of the "whorling" noise?

Does any noise at all from the timing belt area imply a shortened belt life?
What about bearings?

Is the (presumed) shortened bearing life due to heat from excess friction, or
due to the shafts spinning slightly out of round from the belt pulling on them?

To be more precise with setting the belt tension, is it safe, as this fellow
says, to apply tension to the belt with the engine running and idling? That
way the noise would be immediately detectable. I did the best I could
measuring the belt deflection with the engine off. Honestly though, I was
guessing at the force to check the belt deflection since I knew of no way to
precisely create the force quoted in the shop manual. I just pressed on a
floor scale to obtain the number and then tried to press exactly that hard on
the belt.

When tensioning it my overall strategy was to try to get it to the point where
the tension was minimized but where there was no back and forth play in the
belt as I turned the crank, and I believe I succeeded there.

Or maybe new belts make noise as they break in. I've never done one on my car
before so I wouldn't know. It is a Gates belt. I do have a new tensioner.

Ryan Underwood wrote:
>
> I have a pretty standard timing belt setup; two gears, a water pump, and a
> tensioner/idler.

Doesn't your car have an automatic tensioner?

"« Paul »" <"=?x-user-defined?Q?=AB?= Paul
> wrote in message
...
> Ryan Underwood wrote:
>>
>> I have a pretty standard timing belt setup; two gears, a water pump, and
>> a
>> tensioner/idler.
>
> Doesn't your car have an automatic tensioner?

I don't think engines have "automatic" tensioners for cog type timing belts.
I've had cars that used a spring to set the initial tension, but after
manually turning the engine over a couple of time to eliminate the slack,
you lock down the tensioned with a bolt. The problem with these is that the
proper tension for a new belt is different from the proper tension for a
used belt. A spring loaded tensioner like the type used with the multi-vee
accessory drive belts can't be a good idea. Too much chance of the belt
jumping timing. I have also seen procedures that called for the use of a
special tension gage for setting the tension. But on most of the cars I have
owned that had belts just specified a certain deflection under thumb
pressure (or in some cases a specified pressure) at a specified point.
Timing belts do stretch slightly after installation, so even if it whines
initially, this may stop after a few miles. However, in general, I think a
whine is a bad sign. Excessive tension may overload the tensioner bearing
and lead to early failure of the tensioner. The load on the main and cam
bearings is not likely to be a problem (at least to the load on the
tensioner).

Ed

on mine, both idler bearings made a noise when turned by hand, so I
replaced with new
mine has a spring on the tensioner pulley, then a lock down bolt, I
pulled upward with a large hook tool, smoothly but with a lot of force
(enough to move the whole engine) to tension the belt (or you could use
a pry bar at the tensioner), then let the spring hold it in position
while tightening the bolt.
I also have a Burroughs belt tension gauge (easy to be 20, 30 or even
40 pounds off without a gauge if a belt takes 100 lbs.), plus you can
probably find an inexpensive "click type" small belt tension gauge at
NAPA good for smaller belts up to 100 lbs.

"=?x-user-defined?Q?=AB?= Paul =?x-user-defined?Q?=BB?=" <" =?x-user-defined?Q?=AB?= Paul > writes:

>Ryan Underwood wrote:
>>
>> I have a pretty standard timing belt setup; two gears, a water pump, and a
>> tensioner/idler.

>Doesn't your car have an automatic tensioner?

No, it's a manual tensioner. Were it an automatic or a pressure-driven tensioner,
would there be any question?

writes:

>I also have a Burroughs belt tension gauge (easy to be 20, 30 or even
>40 pounds off without a gauge if a belt takes 100 lbs.), plus you can
>probably find an inexpensive "click type" small belt tension gauge at
>NAPA good for smaller belts up to 100 lbs.

Oh, that's a good idea. Thanks.

Ryan Underwood wrote:
>
> "=?x-user-defined?Q?=AB?= Paul =?x-user-defined?Q?=BB?=" <" =?x-user-defined?Q?=AB?= Paul > writes:
>
> >Ryan Underwood wrote:
> >>
> >> I have a pretty standard timing belt setup; two gears, a water pump, and a
> >> tensioner/idler.
>
> >Doesn't your car have an automatic tensioner?
>
> No, it's a manual tensioner. Were it an automatic or a pressure-driven tensioner,
> would there be any question?

True. What engine are you working on? I am familiar with GM and some
imports but not much else.

C. E. White wrote:

> I don't think engines have "automatic" tensioners for cog type timing belts.

They are used. Toyota and Mitsubishi come to mind, but there are other
instances. Automatic tensioners are constructed of a steel or aluminum
cylinder with a spring loaded, hydraulically damped piston which
applies pressure on the tensioner pulley frame - which itself is
mounted on a pivot. There are usually a series of pinholes in the
housing and the piston so that, when compressed, the tensioner can be
pinned in position to make installation easier. The pin is removed
once all of the timing components are in place; then the piston expands
quickly to apply pressure to the tensioner pulley.

Toyota MDT in MO

If your belt uses a manual tensioner or no tensioner, try the method
recommended by VW: pinch the belt midway its longest span and twist
it. When the tension is right for a timing belt you should be able to
twist it almost exactly 90 degrees. I don't know if this method works
with automatic tensioners.

In article . com>,
says...
>
>
>If your belt uses a manual tensioner or no tensioner, try the method
>recommended by VW: pinch the belt midway its longest span and twist
>it. When the tension is right for a timing belt you should be able to
>twist it almost exactly 90 degrees. I don't know if this method works
>with automatic tensioners.

How does this account for people with different hand strength?
---------------
Alex