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Idler pulley advice
r1_pete - 16/1/08 at 09:15 AM

I need to add an idler pulley to my phase 3 zetec install to run the coolant pump anticlock. When the belt wraps round the pulley with the v grooves inwards, do I need a grooved pulley, or will a plain one be ok? I've looked at pics of the westfield one and that looks plain but cant be sure.
Cheers.
Pete.

BenB - 16/1/08 at 09:45 AM

It should be a grooved pulley....

Otherwise the contact area will only be the end of the grooves. This could lead to slipping and early wear to the belt.....

indykid - 16/1/08 at 12:01 PM

quote:
Originally posted by BenB
It should be a grooved pulley....

Otherwise the contact area will only be the end of the grooves. This could lead to slipping and early wear to the belt.....


if it's just an idler pulley, surely there'd be very little resistance, so no torque would be transmitted at the interface.

i'd be more swayed to it being ok as long as it's not driving anything.
tom

BenB - 16/1/08 at 12:31 PM

There is little resistance so you might get away with it.... Then again....
Slippage is a worry though. After all, the multirib belt is only prevented from slipping (unless you've got shouldered plain idler pulleys) but the ribs on the other pulleys. If you start replacing them with plain pulleys you might get lateral belt slip

r1_pete - 16/1/08 at 12:41 PM

It is just an idler, wont be driving anything, just serving to wrap the belt round the coolant pump pulley to provide a good contact area like this:

r1_pete - 16/1/08 at 12:42 PM

It is just an idler, wont be driving anything, just serving to wrap the belt round the coolant pump pulley to provide a good contact area like this:

tim windmill - 16/1/08 at 01:29 PM

i am using the zetec blacktop and i have removed the original tension pulley and butchered this a bit and have mounted this at the other side to act as the idler pulley. It seems to work okay but have not driven in real anger yet

r1_pete - 16/1/08 at 02:18 PM

Thanks, I dont have the original idler, is it v'd or plain? might be easiest to buy one if its v'd, rather than spending a couple of hours at the lathe....
Cheers.
Pete.

FazerBob - 16/1/08 at 08:30 PM

I had the same problem with my Zetec, but found a different solution. First changed the pump for an Escort one (which runs clockwise) then a quick visit to the local scrappy for an Escort Zetec water pump pulley (£5). The belt now runs safely round crank, alternator and water pump, with no idler needed.

Schrodinger - 16/1/08 at 09:37 PM

There isn't an escort water pump that fits the blacktop.

stevebubs - 17/1/08 at 01:00 PM

I originally left the original power steering pump in place to maintain belt patter, but running it dry (unsurprisingly) led to the bearings in the pump melting.

I then ran mine the wrong way (v's of the belt on a flat pulley) for a few weeks before the inverted impellor turned up from the states.

Temperatures at the time were low 20s and I had no issues (was running car in prior to Le Mans). However I wouldn't have felt happy running in that configuration for a prolonged period of time - hence swapping it out.

If using the original pump, I have heard of escort and fiesta idlers being fitted in the Power Steering pump location. Perhaps worth a trip down the scrappies and having a look around.

stevebubs - 17/1/08 at 01:04 PM

Setup below is not recommended - power steering pulley bearings will melt within a short period of time

stevebubs - 17/1/08 at 01:08 PM

One other novel solution I've seen is have an alternator mounted in the power steering position. However, instead of mounting the body of the alternator next to the engine, it was mounted sticking forward (i.e. facing the "wrong way", with the power connectors towards the front of the car)

Look at www.zetec-cat.co.uk for ideas on how to fabricate an effective idler/tensioner assembly.