Serpentine belt routing
Andrzejsr - 27/2/22 at 09:13 PM
I am preparing a Zetec blacktop engine for a kitcar. I have read about proper direction of water pump, made a bracket which a belt tensioner taken
from this engine.
Now I wonder what for is the "free" pulley , in many belt routings I have seen on Zetec engine users .
Is it ok to route the serpentine belt in the way marked green on picture below? or it will be to long distance from tensioner to alternator ?
And better to keep this free pulley and route in pink marked way ?
In my engine there is cutted and flattened timing belt aluminium cover, so no disturbing metal part as it is originally in Zetec E.
Are there any rules, that belt on the alternator pulley must touch it on for example 1/2 of pulley circumstance ? never heard, but maybe? all pictures
I have found of this serpentine belt, are in the pink routing way. Are there other reasons than thi protruding aluminium time belt cover ?
indykid - 27/2/22 at 10:36 PM
As you've noted, the idler is there to increase the belt wrap on the alternator pulley. The more wrap on the pulley, the more torque it can
transmit without slipping.
Given you're unlikely to have a heated front and rear screen, heater blower and heated seats all running at the same time in a kit car like you
might in the original application, you might get away with the reduced wrap but you might also end up with a belt that screams when you put the
headlights on.
If the idler you have needs replacing, try running the green routing but if it's ok, the original layout is pretty well guaranteed to work. If
you follow the pink route, you won't have to figure out what belt length to run either.
HowardB - 28/2/22 at 08:32 AM
not being familiar with a black top, what is the pulley top right in the picture?
ianhurley20 - 28/2/22 at 08:41 AM
We did the green route and can confirm belt squeal when starting up or putting a bigger load on the electrics. Had to tighten the belt up quite a lot
to get rid of the noise
Andrzejsr - 28/2/22 at 09:13 AM
quote:
Originally posted by HowardB
not being familiar with a black top, what is the pulley top right in the picture?
It is a tensioner pulley I have mounted there , to keep the direction of waterpump rotation, as in Ford Focus in this place is power steering pulley.
Was going to add normal pulley, not tensioner, but thought that would be nice to have a tensioner. Originally it sits below alternator.
Just did some tests, and propably will go thepink-route, because in this routing, tensioner works best. In green it gives small amount of regulation
of belt tension.
[Edited on 28/2/22 by Andrzejsr]
indykid - 28/2/22 at 09:14 AM
quote:
Originally posted by HowardB
not being familiar with a black top, what is the pulley top right in the picture?
It's an autotensioner and idler to increase belt wrap on the waterpump pulley
HowardB - 28/2/22 at 09:21 AM
quote:
Originally posted by indykid
quote:
Originally posted by HowardB
not being familiar with a black top, what is the pulley top right in the picture?
It's an autotensioner and idler to increase belt wrap on the waterpump pulley
thanks for the answer - learning something new everyday
SJ - 3/3/22 at 01:50 PM
Mine follows the green route - no issues with belt slip at all.
I have a small 30a Denso alternator though which might be making a difference.
Stu