Fiesta 57 1.4 diesel breaking aux. belt

In January I put a new alternator and idler pulley onto one of these. One month later and probably only a hundred or so miles and the belt ripped itself apart and pulled off the inconveniently close crank sensor plug. I towed it in and fitted a new belt, I could not see any reason for the failure and put it down as one of those things, or maybe I had misaligned it on a pulley (not very likely, but always possible) Fast forward 4 months with very few miles and the belt has shredded again, but down in Dorset, luckily the elderly lady owner has breakdown cover and they fitted a new belt, he suggests that the alternator must be the cause of trouble, but why? it feels perfectly ok and everything looks lined up. Looking online I can see that auxiliary belt failure on these seems to be a common problem, sometimes taking the cambelt with it, yet no one that I can see has an answer as to why they are failing.

So, has any one got any good ideas? (apart from a layby and a match)

(I replaced the original alternator and idler pulley because they were noisy)

Reply to
Mrcheerful
Loading thread data ...

In January I put a new alternator and idler pulley onto one of these. One month later and probably only a hundred or so miles and the belt ripped itself apart and pulled off the inconveniently close crank sensor plug. I towed it in and fitted a new belt, I could not see any reason for the failure and put it down as one of those things, or maybe I had misaligned it on a pulley (not very likely, but always possible) Fast forward 4 months with very few miles and the belt has shredded again, but down in Dorset, luckily the elderly lady owner has breakdown cover and they fitted a new belt, he suggests that the alternator must be the cause of trouble, but why? it feels perfectly ok and everything looks lined up. Looking online I can see that auxiliary belt failure on these seems to be a common problem, sometimes taking the cambelt with it, yet no one that I can see has an answer as to why they are failing.

So, has any one got any good ideas? (apart from a layby and a match)

(I replaced the original alternator and idler pulley because they were noisy)

The only instance of this I've seen was on an old sherpa diesel which kept breaking fan belts. It turned out that someone had levered the engine in using a putlog on the crank pulley, so the end of the crankshaft was bent, resulting in the belt constantly slackening and tightening with every revolution. In this case though, there was also considerable oil loss from the front cover. I don't suppose it's the crankshaft in your case, but are all the pulleys running true?

Steve

Reply to
shazzbat

OEM belts?

Perhaps there's a lot of sub-standard non-OEM ones around?

Chris

Reply to
Chris Whelan

they all look great, no wobbling, all look in line, no funny noises and the tensioner is the spring loaded type and isn't frantically wobbling about.

Reply to
Mrcheerful

The first breakage was the oem one, the second a gates iirc. Lots of people say they go and check them often, but why? serpentine belts generally outlast the car these days.

Reply to
Mrcheerful

Is there some sort of vibration damper in the pulley (the description of mine says it has one)? I've no idea what that can mean, since it seems solid to me, but if it breaks?

Reply to
Etaoin Shrdlu

Good thought, ceratianly many crank pulleys have a vibration damper and I have changed faulty ones on Fords in the past, I will have a good pull around at it and see if it wobbles. The pulley on the old and new alternators has some sort of one way clutch in it, both looked and felt identical, neither seemed to be any different to a solid pulley, so not sure what they actually do or how their failure could break the belts, which literally seem to be shredded, it is really quite strange. There were no odd noises before the first belt failure and the new belt I fiited in Feb. seemed perfect, again no strange noises or wobbly running.

Reply to
Mrcheerful

Very odd. You'd think with a serpentine type it would simply come off if things were out of true.

Reply to
Dave Plowman (News)

What alternator did you use? Is the free wheel clutch working properly and not seized?

Tim.

Reply to
Tim

I have not yet seen the remains of the latest breakage (the car comes in on Monday) but the previous one was literally torn to shreds, I have never seen one fail like that before. Serpentine belts very rarely fail at all, the only failures I have come across have been when a pulley has locked up (usually the tensioner pulley) and the belt has melted away on the red hot pulley. The only other ones I have changed have been the occasional noisy one, but they are not broken !! Doing a bit of googling turns up that it does have a harmonic balancer type pulley on the crank and they are known to fail, so fingers crossed that is what the problem is, but I would have thought the RAC would have spotted it, they would be the most likely to see and diagnose belt failures on a regular basis.

Reply to
Mrcheerful

On 13/06/2015 13:23, Tim

It was a pattern alternator, The pulley looks exactly the same as original, neither seem to turn only one way, both seem solid. How could that rip the belt apart?

Reply to
Mrcheerful

Are stretchy belts more likely to fail than the more solid ones? There must be something in them to make them more elastic.

Reply to
Etaoin Shrdlu

This belt is a conventional one with a spring loaded tensioner.

Reply to
Mrcheerful

In a different life I once sailed Chief Engineer on a small oil tanker. The cargo pump was belt driven, two bloody big rubber belts. Shoreside replaced them as planned maintenance. After that they kept tearing themselves to shreds. Turns out the loops at the ends of the belts were different sizes. Just a suggestion.

Reply to
Mr Pounder Esquire

En el artículo , Mrcheerful escribió:

Suggestion: look for a bolt or stone in the bottom of the crankshaft pulley housing? Normally it would sit quietly there but maybe it's being thrown up as e.g. the car goes over a pothole, and is getting caught in the belt.

Reply to
Mike Tomlinson

Good idea, can't say that I remember anywhere that could be a hiding place but I will be looking very closely at everything that is vaguely near the belt, like I said, it is so strange the way the belt has failed, apparently the lady has got the second belt and the RAC report, so that may shed some light. I am hoping it is just the bottom pulley :)

Reply to
Mrcheerful

When the harmonic damper failed on my 320d, the outer pulley jumped out from under the belt and left the belt running on the smooth inner part of it. It was only a little squealy belt syndrome that got me to have a shufti!

Reply to
Scott M

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.