Squeaky Belts driving me mad!!

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mrbump
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Squeaky Belts driving me mad!!

Post by mrbump »

Hi all,
I have in my garage both a 405 td and also zx td. The 405 has always had a squeaking belt when it was idling, or when the power steering is on full lock (or all electrics are on). Now, I found that the belt was quite loose even when the adjustment pulley was all the way down with the original belt. I had a look in the book and found that the belt was 1 inch longer than the specification and so bought a shorter one (the correct one according to the book). Once fitted the belt was quiet as a mouse[;)] for a couple of weeks, then it started again. Now the adjustment pulley is again at its extent and squeaking has recommenced. What is happening here? Is the belt stretching? Is the automatic tensioner too weak?
Now it seems my zx feels left out and has started the tell tale signs of a little 5sec startup squeak first thing in the morning. I have also felt the power steering dissapear on wet days when turning the car on full lock (belt slip). I have the correct belt here and there is still plenty of tensioner still to go, with the tension on the belt being spot on as well. Also all covers and wheel arch liners are in place. It seems the sqeaking is coming from the crankshaft pulley itself.
It also seems that every other cit/pug/rover with this deisel engine i see is a squeaker as well! So it is a common problem methinks.
SO.... has nobody yet found a permanent cure to this aurally irritating phenomenon? There must be another soultion to the old 'just replace the belt again' excuse? My zx has had a new belt since 5000 miles when the engine was rebuilt. First signs of squeakiness about 500miles ago. Belt tension was checked and pronounced OK. Should I now be changing my belt every oil change!!!!!
Yours in desperation.
tomsheppard
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Post by tomsheppard »

Assuming that the pulleys are free from oil then there is a product called Sprayzol that can help.
You might like to try a bit of shoe polish on the belt. An old remedy, it often works.
vanny
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Post by vanny »

Mine really go to me the other day. Let the engine warm up and gave it the old escort treatment. Need to buy a new can of WD40 though ;) And it has stopped squeling so far. My suspision is that its not the belt that actually causes the squealing, but one of the pulleys.
Robin
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Post by Robin »

Remember that the pulleys wear too. If you can see a bright area at the root of the pulley with a new or newish belt running then it's the pulley that has worn. Vee drive belts grip on their sides, the wedge action forcing the higher friction to drive the alternator or pumps. If it bottoms out then no amount of tightening will cure the slip which is what you can hear in the sqealing. The main culprit will always be the smallest pulley which by definition is the one with the greatest load and therefore more prone to slip and thence wear. I suspect it is the alternator pulley that is the main culprit.
From personal and bitter experience I have found that many low cost belts are not built to very high accuracy over the taper and therefore wear is accelerated until the angle is 'worn' correct. By which time the belt is often at the end of the adjustment or running in the bottom of the smallest pulley.
In severe cases with known good quality belts then I am afraid it's a new pulley set or at least a replacement for the smallest in the train. R
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Post by alan s »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by vanny</i>

Mine really go to me the other day. Let the engine warm up and gave it the old escort treatment. Need to buy a new can of WD40 though ;) And it has stopped squeling so far. My suspision is that its not the belt that actually causes the squealing, but one of the pulleys.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Got to agree with most things said so far but might also ad that a common one can be the harmonic balance on teh way out. The harmonic balance is the pulley on the crank which has a vulcanised centre hub that deteriorates with age and can cause the pulley to separate and in the process either squeak itself or allow a slackening of the tension thereby causing the belt to squeal.
Another in particular on the BX16V/Mi16 engines is that the tensioner is expensive and in some cases NLA and as a result a belt is supplied that goes around the three pulleys forming a triangle shape. This seems to limit the area of the pulley covered by the belt which again creates a squeal. With the adjuster in place, the belts will then cover say 110 degrees of the pulley instead of around 90. As serpentine belts are available in a variety of sizes, I have often thought that the original jockey wheel/tensioner could be replaced with another similar one, even a cambelt tensioner and if the difference couldn't be made up by belt resizing, then retensioning should fix the problem.
Slightly O/T but I thought I'd throw that one into the ring as so many seem to have this belt tension problem & for a variety of reasons.
Alan S
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mrbump
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Post by mrbump »

Robin,
If I understand the premise of your theory correctly, why then doesn't the belt just wear itself to the shape of the (worn) pulley and then stop squealing?
Wouldn't it be possible to lightly grind off the tops of the ridges on the belt itself to stop it bottomming out? Logically it will be the part of the belt/pulley contact that generates the most friction that will wear quickest. So it is probably the sides of the v wearing first, allowing the top of the v to cut into the belt, and the bottom of the belt to touch the bottom of the pulley. So, if you could grind a bit off the belt ridges and a bit off the pulley ridges it will provide a tighter fit?
I do think however, that the squeal comes from the main crankshaft pulley on mine. For two reasons: If I squirt each pulley separately and on separate occasions when the same level of noise is there, it dissapears QUICKEST when the main pulley is squirted. It will always eventually dissapear though as the wd40/water/degreaser makes its way around the path of the belt. And also because for any pulley to slip i.e. alt, steering or a/c, it needs to require a greater turning force than the belt friction can provide. Whereas the crankshaft pulley will slip if the sum of all other pulleys' required forces is greater than the friction around the crankshaft pulley can provide. E.g why does it slip at idle and go away when you lift the revs? The crankshaft pulley turns faster, the others dont change?. Also, there is more contact area spread over the three other pulleys than there is on the crankshaft pulley.------- i think..[|)](headache) Its quite complicated when you get to it!!
Of course the answer is a set of nice sharp new pulleys, but I am sure that would cost more than my car!!! Whatabout using a different belt with fatter ribs? Anything spring to mind?
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Post by Robin »

Errm, Mr Bump you may have found the flaw in my argument here. I had assumed we were discussing a conventional vee belt. Are you discussing a poly vee belt here, the wide one with lots of little vees on it?
If so then the wear factor on the sides is not so pertinent but still possible.
The pulley that turns the fastest is the smallest in diameter. So really the crankshaft pulley should rotate slowest being the larger.
However the stretch in low quality poly vee belts is even worse than the single vee belt variety. Tension is critical but they do stretch remarkably. Always try to use reliable makes, such as Gates or OEM's. R
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