belt question

[owen]

I have a thorneycroft t90 engine . it has the convetional raw water pump driven off the main shaft by a belt. the belt was slipping and could not be tensioned any further. the belt was stamped 13x841(13mm widthx841 length).there was not a direct replacement available but i took a selection down to get the best fit. In fact the only one which had any chance of fitting was a 13x875 and that was a real struggle to fit. could the original belt have stretched that much??

 

[cliff]

IIRC The belt also drives the alternator so you need to slacken the alternator and swing it in tight to the engine to allow the correct size of belt to be fitted. Unless the belt was very badly worn it should not have stretched 34mm (~1 5/16").
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"Artificial intelligence is no match for natural stupidity"

 

[owen]

sorry my mistake in explanation. the water pump has a completely separate belt to the alternator.there are 2 pulleys on the mainshaft one for the alternator and one for the waterpump.

 

[Gordonmc]

Owen,
Precisely the problem featured in my post of last week.
There is very little adjustment in the T90 raw water pump pulley and at full adjustment my pulley was fouling the engine box.
The solution was to get a link belt from ASAP Supplies. The intention is to swing the pump in as far as it goes, then make up the belt to length. It can be fitted/removed without tools, another bonus. I have ordered a metre length which should give a few spare links.
Waiting for delivery... I will update once its fitted if you are interested.

 

[cliff]

Ooooh, that is different - there must be a tensioner surely? either that or the water pump has to move to tension the belt. You did say it was a vee belt, didn't you?.

 

[owen]

yes it is a vee belt and the tensioning is done by moving the pump on its pedestal outwards.

 

[owen]

yes i saw your post gordon. i would appreciate your update when u fit the link belt.as a matter of interest did you note the length of the belt when you took it off?

 

[compie1]

Owen,

If you can not get the belt over the pully when fully released you can remove the pully put the belt on and bolt the pulley with belt back on the alternator.

regards,

Tom VC

 

[cliff]

[ QUOTE ]
yes it is a vee belt and the tensioning is done by moving the pump on its pedestal out-wards.

[/ QUOTE ]Have you tried moving the pump right in on its pedestal and fitting a 13X841 belt?. You may be able to source the correct length belt from Fenners or the like.

Oh yes, before I forget, the link type belts do tend to be a bit noisier than vee belts and can chew through ordinary steel or aluminium pulleys quite quickly or so the chap in Fenners advised me when I went to replace the belt on my engine a few years ago - maybe technology has changed since then though.
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"Artificial intelligence is no match for natural stupidity"

 

[owen]

yes I thought about removing the pulley,fitting the belt then refixing the pulley but in the end cheated by putting the belt on as much as i could with the pedestal pulled right in then turning over the engine on the starter for a second. that was enough to flick the belt on.

 

[Gordonmc]

I didn't get the length of the old belt... when I took over the boat there was a collection of moteley old belts in the locker, none the same size, so I have been working blind.
I too have been trying to get the right tension by removing the whole pump, adjusting the mounting flange and refitting with the belt on the pulley. This is very unsatisfactory and wouldn't be a solution as an emergency fix at sea.
According to the blurb the link belts are fine for permanent replacement. I can't see the rivets doing any harm to cast iron pulleys.

 

[owen]

thanks gordon i should be v interested in how things work out