Timing Belt Idler Pulley question

On Jan 24, 6:38 pm, Natman > wrote:
> On 24 Jan 2007 09:39:03 -0800, wrote:
>
>
>
> >I am not arguing - but I am getting several different answers.
> >1. It does spin freely
> >2. It does not spin freely
> >3. It should not spin
> >4. and on and on!!OK fair enough. This is a difference in semantics about what "spin
> freely" means. Let me try to resolve it.
>
> 1) The pulley HAS to be free to turn when it is installed. That's why
> Mazda put a bearing in it! If you start the car with the idler unable
> to turn your belt will quickly destroy itself in a cloud of blue
> smoke.
>
> There is no room for intellegent discussion of this point, any more
> than whether or not your engine really needs oil or "It's only flat on
> the bottom", do tires really need air?
>
> THE PULLEY *MUST* BE ABLE TO TURN!
>
> 2) The pulley should turn smoothly with no trace of roughness.
>
> 3) You should be able to feel the resistance of the grease that is
> packed inside. If it spins freely for several revolutions like a
> roller skate wheel, then the grease is gone and it needs to be
> replaced.
>
> Best bet: just buy two new pulleys.

Two new pulleys are in the mail.

On Mon, 22 Jan 2007 13:26:47 -0500, "Pete" <pbreemhaar(at)hotmail.com>
wrote:

>
>"Natman" > wrote in message
.. .
>> On 21 Jan 2007 16:49:18 -0800, wrote:
>>
>> It should definitely spin after torquing. I don't know if you need to
>> buy a new one or not, but if it doesn't spin freely, loosen it and fix
>> what ever is hanging it up.
>
>I may be missing something here, but I remember torquing the idler pulley
>after having the replacement timing belt in place. That being the case,
>how is the idler pulley gonna spin freely if it applying tension to the
>timing belt?
>As I say, maybe my brain is suffering from frostbite, but...
>
>Pete
>
The center of the pulley is fastened to the engine block and stands
still. The outside of the pulley spins when the belt moves. The
difference is resolved by a ball bearing in the middle.

I guess it boils down to this-- The pulleys have a bearing that is sealed.
Bearings that have grease lubrication should turn without any roughness, and
have a very light resistance due to the grease. To me turning freely for a
bearing meets the conditions above. Now if you think turning freely means
that you can easily spin the bearing at a high speed, and it continues to
spin for many revolutons without more applied energy, then we have two
different ideas of turning freely as applied to lubricated bearings.

Now if you want a bearing that turns more freely than most, I'd like to
mention the bearings on a moderately large generator powered by a multi
thousand HP motor.
First, the bearings are pressurized to a fairly high pressure (~5,000PSI),
and are oil lubricated. Next you push with both hands against the shaft and
coupling between the motor and generator. After several minutes, the shaft
will turn slowly. After you remove your hands the shaft will contine to turn
for several minutes, but for less time than you pushed on it.
(The generator was designed to be spun up to speed by the motor, then the
motor was turned off priot to applying a large load to the generator.)
The intended use was to test electrical devices under catastrophic failure
conditions. The generator was capable of dumping a meagawatt per phase or so
into a load.
(Stored energy in the rotating mass of the generator) The generator was
mounted on what was roughly a cube of concrete and steel structure about
25x25x25 feet.
If the bearings were to seize with the generator turning at speed, and not
connected to the mounting structure, it would go thru a concrete block wall
with ease, and continue to roll on open ground for quite a distance, ending
up on what used to be a four lane part of route 66, now 55.
..
"BRUCE HASKIN" > wrote in message
...
> It should NEVER spin freely ! If it spins when you hold the center and
> move the outer part, throw it in the trash! You should be able to turn
> it and have some drag. If you can spin it like a bike wheel, the next
> thing you can expect is the idler will come out thru the front cover
> some time when you are turning up the wick and hit 7,000 RPM. I have
> seen two cars come in after that came about. Very ugly !!!
>
> "If it spins with very little effort, it is shot !"
>
> Bruce Bing '03 LS
>

Chuck, It's not what "I think", is the point here. I know when the belt
tentioner and idler for a miata are ok to use and when to throw them
away. It was a question that was asked to the people on this site.
Should it "Spin". It looks to me that we have long over answered that
question ! Thank you for the long disertation on the subject you
covered. I don't know how I could have gone on in life without knowing
all of that. Thanks again :-)

Bruce Bing '03 LS

"Chuck" > wrote:

>I guess it boils down to this-- The pulleys have a bearing that is sealed.
>Bearings that have grease lubrication should turn without any roughness, and
>have a very light resistance due to the grease. To me turning freely for a
>bearing meets the conditions above. Now if you think turning freely means
>that you can easily spin the bearing at a high speed, and it continues to
>spin for many revolutons without more applied energy, then we have two
>different ideas of turning freely as applied to lubricated bearings.
>
>Now if you want a bearing that turns more freely than most, I'd like to
>mention the bearings on a moderately large generator powered by a multi
>thousand HP motor.
>First, the bearings are pressurized to a fairly high pressure (~5,000PSI),
>and are oil lubricated. Next you push with both hands against the shaft and
>coupling between the motor and generator. After several minutes, the shaft
>will turn slowly.

Ah, the wonders of Newtonian viscosity.

> After you remove your hands the shaft will contine to turn
>for several minutes, but for less time than you pushed on it.

Eat more spinach.

Leon

>(The generator was designed to be spun up to speed by the motor, then the
>motor was turned off priot to applying a large load to the generator.)
>The intended use was to test electrical devices under catastrophic failure
>conditions. The generator was capable of dumping a meagawatt per phase or so
>into a load.
>(Stored energy in the rotating mass of the generator) The generator was
>mounted on what was roughly a cube of concrete and steel structure about
>25x25x25 feet.
>If the bearings were to seize with the generator turning at speed, and not
>connected to the mounting structure, it would go thru a concrete block wall
>with ease, and continue to roll on open ground for quite a distance, ending
>up on what used to be a four lane part of route 66, now 55.
>.
>"BRUCE HASKIN" > wrote in message
...
>> It should NEVER spin freely ! If it spins when you hold the center and
>> move the outer part, throw it in the trash! You should be able to turn
>> it and have some drag. If you can spin it like a bike wheel, the next
>> thing you can expect is the idler will come out thru the front cover
>> some time when you are turning up the wick and hit 7,000 RPM. I have
>> seen two cars come in after that came about. Very ugly !!!
>>
>> "If it spins with very little effort, it is shot !"
>>
>> Bruce Bing '03 LS
>>
>
--
Leon van Dommelen Bess, the Miata Bozo, the Miata
http://www.dommelen.net/miata
The only thing better than a white Miata is two white Miatas

On Jan 29, 4:56 pm, (Leon van
Dommelen) wrote:
> "Chuck" > wrote:
> >I guess it boils down to this-- The pulleys have a bearing that is sealed.
> >Bearings that have grease lubrication should turn without any roughness, and
> >have a very light resistance due to the grease. To me turning freely for a
> >bearing meets the conditions above. Now if you think turning freely means
> >that you can easily spin the bearing at a high speed, and it continues to
> >spin for many revolutons without more applied energy, then we have two
> >different ideas of turning freely as applied to lubricated bearings.
>
> >Now if you want a bearing that turns more freely than most, I'd like to
> >mention the bearings on a moderately large generator powered by a multi
> >thousand HP motor.
> >First, the bearings are pressurized to a fairly high pressure (~5,000PSI),
> >and are oil lubricated. Next you push with both hands against the shaft and
> >coupling between the motor and generator. After several minutes, the shaft
> >will turn slowly.
>
> Ah, the wonders of Newtonian viscosity.
>
> > After you remove your hands the shaft will contine to turn
> >for several minutes, but for less time than you pushed on it.
>
> Eat more spinach.
>
> Leon
>
>
>
>
>
> >(The generator was designed to be spun up to speed by the motor, then the
> >motor was turned off priot to applying a large load to the generator.)
> >The intended use was to test electrical devices under catastrophic failure
> >conditions. The generator was capable of dumping a meagawatt per phase or so
> >into a load.
> >(Stored energy in the rotating mass of the generator) The generator was
> >mounted on what was roughly a cube of concrete and steel structure about
> >25x25x25 feet.
> >If the bearings were to seize with the generator turning at speed, and not
> >connected to the mounting structure, it would go thru a concrete block wall
> >with ease, and continue to roll on open ground for quite a distance, ending
> >up on what used to be a four lane part of route 66, now 55.
> >.
> >"BRUCE HASKIN" > wrote in message
> ...
> >> It should NEVER spin freely ! If it spins when you hold the center and
> >> move the outer part, throw it in the trash! You should be able to turn
> >> it and have some drag. If you can spin it like a bike wheel, the next
> >> thing you can expect is the idler will come out thru the front cover
> >> some time when you are turning up the wick and hit 7,000 RPM. I have
> >> seen two cars come in after that came about. Very ugly !!!
>
> >> "If it spins with very little effort, it is shot !"
>
> >> Bruce Bing '03 LS
>
> --
> Leon van Dommelen Bess, the Miata Bozo, the Miata
> http://www.dommelen.net/miata
> The only thing better than a white Miata is two white Miatas- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -

Of course - the new idler pulley showed up - took everything apart to
install it - and it works much better than the old one. But to make
my life ever more challenging - the company did not ship the correct
tensioner pulley - despite what the invoice said they sent me another
idler pulley for another type vehicle. Oh yeah - the saga continues.