Board logo

Timing Belt "Walk"
Barksavon - 21/6/19 at 08:56 PM

We've put the timing belt on our ST170 this evening....everything seemed to go quite well, camshafts line up after turning g engine etc..... however after turning engine over a few times the belt is 'walking' off the pulleys quite substantially

Has anyone else experienced this problem, could it be something to do with the tensioner....?

Mr Whippy - 21/6/19 at 09:38 PM

Well can't be too many things... Are all the pulleys mounted tight, is the water pump worn. If you put a straight edge on any of the pulleys is it sitting level? I'm assuming the crank shaft pulley is fitted as that's what usually prevents the belt walking off.

theconrodkid - 22/6/19 at 08:19 AM

there should be a plate on the outside one of the pulleys that stops the belt walking , if that is missing it will walk

Barksavon - 22/6/19 at 08:53 AM

Everything is straight and level, we have fitted a new crankshaft timing pulley.
On the ST170 Zetec the water pump isn't driven by the timing belt so that's not an issue.

There are no plates to go on the outside of the pulleys and to be honest on all the online photo's of these engines ive looked at i haven't seen any plates on any of them. I know what you mean but not sure they are fitted/required on this engine???
Thanks for the replies

perksy - 22/6/19 at 10:41 AM

Sorry not too familiar with these engines but does it have a spring loaded tensioner?

*If* it does are you absolutely sure its set correctly to the instructions from the Kit/belt manufacturer?

big_wasa - 22/6/19 at 11:07 AM

The aux pulley would stop it walking off the bottom pulley.

In the cam belt cover backing plate there is a rectangle cut out to accept the tang on the tensioner. If this is not in its hole the tensioner won’t sit square. Did you fit a new idler ? Ie a full kit ? This has a spacer on the back and buts up-to the same plate.

With the tensioner set you should be able to twist the belt 90deg with your finger and thumb on the longest length.

[Edited on 22/6/19 by big_wasa]

perksy - 22/6/19 at 11:15 AM

*If* you fitted a Gates kit make sure you follow their instructions to the letter

Barksavon - 22/6/19 at 12:33 PM

It's a Dayco kit with new spring loaded automatic tensioner.
We did put the aux pulley on the crank and it did lessen the amount the belt 'walked' off the other pulleys but not significantly.
Don't know if we were doing something wrong but when we lined the pointer on the tensioner up with the window in the back plate and then tightened the tensioner bolt to torque it was a bit of a pig keeping the pointer lined up.

Think we'll have to take everything off and start again.

rusty nuts - 22/6/19 at 04:17 PM

Double check the tensioner is fitted correctly