Northern Auto Tech - ECU and Blue & Me Repairs

General JTD 8v Alternator belt coming off

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General JTD 8v Alternator belt coming off

MazCinq

MazCinq

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ok, so I had a new belt and tensioner fitted a couple of weeks ago, I drove the car up north and back, trip of 750miles, and it was fine, then the other day, Mon I think, I came out to use the car and the belt had come off, took it back to the garage who happily re-fitted it, al was well again, until this morning, when, bam, the same thing, took it back to the garage who happily re-fitted the belt, I watched them while they did it, once fitted they lowered the car back down and started it at which point there was 3 loud clicks (Tensioner tightening I think) and the belt came off again, they then lifted it back up and re-fitted the belt, lowered the car down and started it, ok 1 loud click this time but belt stayed on, raised the car up with engine running to check it was all ok and everything seems fine. no play in the pullies or idlers, belt runs true, all seems fine with the world again.


Has any-body come across this issue before as I am fast losing trust in the car which is a shame because I love driving it and its perfect for what I need.
 
First thought, the tensioner is not square against the belt. There have been issues on here, a search may find them. A loose or poorly fitted tensioner will cause damage to the block, so needs to be sorted.

Second thought, a lot of the diesels have a freewheeling alternator pulley. This is supposed to damp out some of the engine vibration to protect the alternator. These fail, and is probably what causes the alternator body to crack. Have a good look at the alternator body, ensure all mountings are tight and with th belt off, check the pulley for easy rotation one way and turning the alternator the other.

Third. Aircon? If you have aircon, the clutch on the drive pulley will click as it engages. Does the aircon work? A tight/seiziing aircon pump will pop the belt.

Fourth. Does it also drive the water pump? If so, check that for free running.

From below or above, when running, are all the pulleys in line? Any misalignment will pop the belt off. Modern multi-rib belts will not tolerate misalignment.
 
First, Tensioner is perfectly square and fitted tight, not that for sure.


Second, I will check this out maybe tomorrow.


Third, Aircon has been checked I know for sure as I was there when it was checked and it works fine.


Forth, nope I believe that off the timing belt.


Fifth, Yup, all pullies and idles are straight and true.


it has me baffled as I did a 750mile trip up north and back with 3 days of driving around while I was up there and no issues, it started a few days after I got back, it doesn't jump off while running, only seems to be when its been turned off and then when its re-started its off, mind it hasn't done it since I posted about this issue. its got me not trusting the car
frown.gif
 
Perhaps there is a fault with the new belt broken strands within the belt or something like that,,
Do you still have the old belt just to try and see if it makes any difference and if you have the old belt to fit back on you can see what happens and will give you an idea if belt related, also did you have correct size belt fitted when I replaced tensioners and idler pulley I fitted a new 6pk1270 as was already fitted to my 53 plate jtd 115 m/w with air con, I did notice when looking for a new belt there were various sizes being advertised for my stilo but went for what was fitted initially the new belt I fitted caused squeaks on start up so went and paid out for gen item from fiat which cured that so even though I fitted a new belt it did cause a problem though not as severe as the problem you are experiencing.
 
No don't have the original belt as it snapped on me, I am going to look into the alternator clutch thing, see if that's stuck, if it is, I guess it's a new alternator.
 
The garage that has done this work is pretty useless for hearing these loud noises and expecting you to drive off even after the belt comes off while at the garage and they just refit it and act like they fixed it.


1. Do you have the correct belt fitted? The brand and code will be clearly visible on the belt. The belt is possibly too long so that the tensioner is hitting the stops as it tries to take the slack up on starting. Click click click and off she goes! Even with the wrong belt fitted the tensioner can still fully tighten the belt when the car is not moving.

2. Is the correct tensioner fitted?
 
The belt is deffinatly the right one as I watched him re-fitting the belt and it needed the tensioner fully pulled back and the belt was still very tight to get on, I am starting to think that the Alternator freewheel clutch is gone as that would also explain the squeeking i'm getting too.


I will go out and see if I can get a belt brand and part No in abit.
 
mariocinq said:
The belt is deffinatly the right one as I watched him re-fitting the belt and it needed the tensioner fully pulled back and the belt was still very tight to get on, I am starting to think that the Alternator freewheel clutch is gone as that would also explain the squeeking i'm getting too.


I will go out and see if I can get a belt brand and part No in abit.
Click to expand...

If the alternator clutch is gone what difference will it make though?

I think only a specialist parts shop will know if that belt is correct for that engine and on my Punto the shop could only give me two to take away despite their best efforts. They were different by two cm.

On my punto if I dont get the belt organised and partly on the crankshaft pulley it is next to impossible to fit it and yet if i am a third of the way on the crankshaft pulley before i wind up the tensioner there is no struggle.
 
judderbar said:
If the alternator clutch is gone what difference will it make though?

I think only a specialist parts shop will know if that belt is correct for that engine and on my Punto the shop could only give me two to take away despite their best efforts. They were different by two cm.

On my punto if I dont get the belt organised and partly on the crankshaft pulley it is next to impossible to fit it and yet if i am a third of the way on the crankshaft pulley before i wind up the tensioner there is no struggle.
Click to expand...

The punto must be different to the Stilo 115bhp JTD, Alternator has a freewheel clutch in it to stop the kick back from the engine spinning the alternator the wrong way, it is believed that if this fails then if there is kick back when the engine stops it can throw the belt, makes sense the more I think about it with the Squeeky pully bearing somewhere.
 
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