Marking on Alternator belt
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The marks look as though they are caused by a pulley running on the plain side of the belt that may have a scratch or burr. The belt is very shiny so another possibility is that it is too tight.
Your pulley arrangement is different to my MY09 1.4 engine but on mine there is a tensioning pulley above the crankshaft pulley ans another pulley between the alternator and AC compressor, possibly a water pump drive that are driven from the plain side of the belt.
Check to see if you have any pulley's running on the plain part of the belt and if you can see any damage. Also check the tension is not too tight.
Your pulley arrangement is different to my MY09 1.4 engine but on mine there is a tensioning pulley above the crankshaft pulley ans another pulley between the alternator and AC compressor, possibly a water pump drive that are driven from the plain side of the belt.
Check to see if you have any pulley's running on the plain part of the belt and if you can see any damage. Also check the tension is not too tight.
If it interacts with the plain side of belt it will be a plain pulley. Are the marks on the pulley smooth or do they feel like scratches and how deep are the marks on the belt.
On my engine I havent got that part at the top but it appears it sits between the alternator and the AC compressor and has a plain pulley.
The belt isn't catching or rubbing on anything as it rotates is it.
The marks could have been caused by grit or something but its strange there are two.
On my engine I havent got that part at the top but it appears it sits between the alternator and the AC compressor and has a plain pulley.
The belt isn't catching or rubbing on anything as it rotates is it.
The marks could have been caused by grit or something but its strange there are two.
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The plain pulley is smooth and is just below the top pulley, you can see the nut protruding from it.
The marks on the belt are smooth, not grooved
the mark on the right only came about a couple months ago, but the one on the left I just noticed, last time i checked was about 2 weeks ago, before the bad weather hit as I was topping up the screen wash
The marks on the belt are smooth, not grooved
the mark on the right only came about a couple months ago, but the one on the left I just noticed, last time i checked was about 2 weeks ago, before the bad weather hit as I was topping up the screen wash
The engine mounts allow a certain amount of movement even when in good condition. As the deteriorate the movement increases.
To check for contact hold the top of the engine and try to rock it backwards and forwards. You may notice the belt contact something.
To check for contact hold the top of the engine and try to rock it backwards and forwards. You may notice the belt contact something.
Can you see the further routing of the serpentine belt lower down as I think it runs around another pulley on the outside of the belt below the alternator.
This pulley may possibly have some burring on it and may be the 2nd pulley that was replaced . It is worth checking belt tension although I am not sure if this is on a manual adjuster or auto adjusting ,someone else may be able to confirm but if auto adjusting then belt tension should be out of the equation.
If auto adjuster run engine and see if you are getting any excessive flap/vibration of belt with a/c switched both on and off if a/c is fitted as auto adjusters are fitted to minimise belt fluctuations depending on what demands are placed on it.
If there is excessive visual movement/flapping then get it to a dealer and get tensioner checked out as well as all pulleys for damage/burring.
This pulley may possibly have some burring on it and may be the 2nd pulley that was replaced . It is worth checking belt tension although I am not sure if this is on a manual adjuster or auto adjusting ,someone else may be able to confirm but if auto adjusting then belt tension should be out of the equation.
If auto adjuster run engine and see if you are getting any excessive flap/vibration of belt with a/c switched both on and off if a/c is fitted as auto adjusters are fitted to minimise belt fluctuations depending on what demands are placed on it.
If there is excessive visual movement/flapping then get it to a dealer and get tensioner checked out as well as all pulleys for damage/burring.
Hi the idea of auto tensioner is to take out belt fluctuation as more load is put on the alternator so you should really see no change. When you hear the air con compressor start you may see a slight kick/bounce on the belt as it loads but if the tensioner is working correctly it would then take the load out and run without flapping.
I realise this sounds expensive but as a visual check can eliminate a tensioner issue.Do you have any abnormal noises or is it just that you came across this through routine inspection.
Finally you said it is a repeat defect how long ago was the work done? and is it worth talking to the dealer about the repeat occurence of this fault, always worth trying a courtesy call to them.
I realise this sounds expensive but as a visual check can eliminate a tensioner issue.Do you have any abnormal noises or is it just that you came across this through routine inspection.
Finally you said it is a repeat defect how long ago was the work done? and is it worth talking to the dealer about the repeat occurence of this fault, always worth trying a courtesy call to them.
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132 Posts
if you've had the top idler pulley and the auto tensioner pulley changed then the only other thing that touchs that side of the belt is the water pump pulley, maybe that pulley has been marked by a flying stone or something, which is causing the markings on the belt
Just exploded the picture you posted and on zooming in the belt comes off the bottom of the alternator and goes round the next pulley on the outside of the belt then I think goes to the a/c compressor and I suspect it is that intermediate pulley which is potentially burred/scored although you probably will not be able to check this without removing the belt. sorry I can't think of any other way of inspecting it.
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3,111 Posts
Just checked mine and it is the same... so... what is the consensus? :worms:Ongoing problem but now there is a 2nd marking on it
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Belt is only a year old, replaced under warranty along with the top and middle pulley apparently...any ideas?
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1,250 Posts
Just taken one and you can see the plain pulley just above to the alternator one, has a 2 lines on it, but they appear to be smooth when touching it
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Quality of the inside of the belt seems fine
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ANd i just use my finger and managed to rub a bit off the marks on the belt
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I had this problem from last year, it was a whirrinf type noise, took it into the dealers many times and they said they couldnt find whats wrong with it, even though the noise can be heard....I took a clip of it last year
http://youtu.be/Ft-xoz9GwoE
so they replaced a couple of pulleys and the belt, but this time round, the markings on the belt are not as deep
Quality of the inside of the belt seems fine
ANd i just use my finger and managed to rub a bit off the marks on the belt
I had this problem from last year, it was a whirrinf type noise, took it into the dealers many times and they said they couldnt find whats wrong with it, even though the noise can be heard....I took a clip of it last year
http://youtu.be/Ft-xoz9GwoE
so they replaced a couple of pulleys and the belt, but this time round, the markings on the belt are not as deep
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3,111 Posts
Wide engine bay shot.
Close up of belt, similar markings.
Gave it a little rub to see if it was grooved, didn't seem to be.
Different shot of the above. Mine is into the dealer soon for the wiring harness recall, is it worth mentioning? Yours does seem more defined looking at them again.
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1,250 Posts
my belt is more shiny, the harness recall i had done on friday, i think it was just a visual check so it didnt take long, the technician didnt notice mention anything even though he would have seen it.
I have noticed though that when driving, past 4k rpm there is a slight whine which im sure i didnt notice before, when you have chance you see if its the same? dont accelerate hard, just gently from 2k to 5k see if you can notice anything
I have noticed though that when driving, past 4k rpm there is a slight whine which im sure i didnt notice before, when you have chance you see if its the same? dont accelerate hard, just gently from 2k to 5k see if you can notice anything
Jason
I agree apart from the parallel lines the belt looks fine. Are there any strange noises this time and did the dealer change the plain pulley with the black marks? Does rubbing the pulley with a cloth have any effect on the black marks? Can you see any similar marks on the other plain pulley?
J H
Is your pulley marked in the same way?
As Jason can remove some of the mark on the belt with his finger I'm begining to think the marks are caused by dirt or debris getting crushed between the belt and pulley. You certainly need to check the other plain pulley.
It would certainly be worthwhile if J H obtained an opinion from the dealer.
I agree apart from the parallel lines the belt looks fine. Are there any strange noises this time and did the dealer change the plain pulley with the black marks? Does rubbing the pulley with a cloth have any effect on the black marks? Can you see any similar marks on the other plain pulley?
J H
Is your pulley marked in the same way?
As Jason can remove some of the mark on the belt with his finger I'm begining to think the marks are caused by dirt or debris getting crushed between the belt and pulley. You certainly need to check the other plain pulley.
It would certainly be worthwhile if J H obtained an opinion from the dealer.
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