New belts whine?

[Eldavo]

The mechanic who did my belts yesterday told me that when he changed the belts there is an idler pulley used to stop belt flex under acceleration that should have 1mm of clearance on either side between it and the belt. He can't get that clearance on each side so there is a definite whine from the engine where the balanceshaft belt is rubbing slightly.
Is there an updated and slightly smaller pulley? He thinks the belt spec is slightly different from the original ones too.
On the plus side, one of the balanceshafts was about 3 degrees out, now sorted and the car runs so much smoother, just whiney!

 

[mik_ok]

Whining belts (particularly when the engine is cold) is usually an indication that the tension is too high.

 

[rcsalmons]

If you are talking balance belt there should be a 0.5mm clearance between the idler pulley and the lower balance shaft gear with a 1mm deflection on the longest run IIRC.

I'd take it back to your mechanic with a copy of the workshop manual and get him to put it right.

Rich

 

[Eldavo]

Thanks, that's useful to know. It is the balance belt and he swears that he can't get adequate clearance on both sides but this may well be down to tightness of the belt. Will have a chat with him first but may then go to a local indys for a tension check with the funky tool if it isn't resolved first.

So there is definitely no pulley size change in the specs over the years?

 

[PSH]

Hi Eldavo

Belt whine as already stated means the belt is to tight, if the mechanic is not familiar with Porsches he may think the belt is too loose when set correctly and has over compensated to get it to how he think's it should be? Common mistake for the balance shaft belt as very few mechanics have even seen such a thing let alone adjusted one...lol
I would get him to adjust it correctly asap, if left too long it will put to much strain on the pulleys , tensioner,waterpump and you don't want any one of those failing.[8|][8|]


Pete

 

[ChasR]

I reckon that the cambelt will be tensioned adequately if he is a mechanic, but the balance belt will need retightening. As said, it is roughly done so that the slack of the belt is just taken out, hence resulting with the clearance that Rich talks of.

When my dad checked the belt, he too found it wierd that the belt wasn't touching the pulley thinking it was wrong until I told him that the balance belts are normally done up quite loosely since all the belts that he can encountered over the decades are normally tight enough for the 90 degrees twist method.

ORIGINAL: rcsalmons

If you are talking balance belt there should be a 0.5mm clearance between the idler pulley and the lower balance shaft gear with a 1mm deflection on the longest run IIRC.

I'd take it back to your mechanic with a copy of the workshop manual and get him to put it right.

Rich

Don't you mean a 10mm deflection on the longest run? It was that on a car with a new cambelt when I checked at EMC.

 

[PSH]

Don't you mean a 10mm deflection on the longest run? It was that on a car with a new cambelt when I checked at EMC

That's what I was told many years ago by a very well known Porsche specialist when I asked what the correct tension was, which is why I've never used them or any other garage,OPC or so called specialist since.( 9 years now)
I'm not saying that it's wrong I use it myself... but what the hell's the point in paying someone a small fortune if they do not follow official Porsche practice...lol

As the old saying goes.. " if you want something done properly do it yourself"... at least you care about the possible outcome as it's your pride and beauty..[8|]


Pete

 

[AntB]

I had my belts changed by a non porsche specialist - they wined a lot!..

Took it to GT One in Chertsey for a check and he said its very common for people to overtighten the belts, especially the balance belts if they dont have the correct tool to measure the tension. He adjusted my 100 miles after fitment and they are virtually silent.

Going back next week as its done 2K now since new belts so doing the standard 2K check for piece of mind (oh and for a Gear box oil change and MOT)

A

 

[pauljmcnulty]

The mechanic who did my belts yesterday

Hi Dave,

Is he a mechanic who knows the cars? I used to have lots of jobs done by my local garage, who also run our Legacy and my van. They were fine for things like MOT and oil change, and were very happy to do repairs to fuel line and handbrake adjustment. They did, however, send me away for things like belts on both the Porsche and the Subaru. They were very happy to tell me that the Subaru main oil seal was a specialist-only repair, and that they'd charge me more in hours than I'd pay at a 944 specialist for some work like, for instance, a clutch or belts. As they were about £40 per hour, and my indy is only a bit more, the hours saved makes it a no-brainer.

 

[Eldavo]

Am thinking of going to a porsche specialist for the belts to be properly tightened as it seems that the balanceshaft belt is probably too tight. As for labour charges, the mechanic I use is a good friend of one of my good friends and does all the major work on his m3 csl and numerous other performance cars. I paid £50 for a new water pump fitted and the belts done, as I said earlier he sorted the balanceshaft timing out too, so I'll let him off overtightening one belt.

Anyone any idea how much/how long it will take an Indy to check and retension the belts?

 

[PSH]

Anyone any idea how much/how long it will take an Indy to check and retension the belts?

Less than 30 mins for check and adjust... it's very easy to just check the belt, probably only 10 mins although you may find they charge a min of 1 hr


Pete

 

[awattam]

Do the alt and PAS belts need to come off to adjust the belts? I have a whine from my belts since I had them changed by a speciallist earlier in the year. I asked them about it when they were checked/re-tensioned and they said it was normal.

 

[PSH]

You can certainly check the belts without removing the alternator/steering belts... the tensioner is behind the lower plastic cover and not so easy to get at without removing lower cover. Having said that it may be possible to just pull the cover back and adjust tensioner without having to remove said belts.


Pete

 

[awattam]

ORIGINAL: PSH


You can certainly check the belts without removing the alternator/steering belts... the tensioner is behind the lower plastic cover and not so easy to get at without removing lower cover. Having said that it may be possible to just pull the cover back and adjust tensioner without having to remove said belts.


Pete

So if I check the belts I'm looking for 10mm deflection in the longest span?

I've changed cam belts before and have gone on a deflection figure. I didn't do the belts on the 944 as I wanted the stamp in the book, kind of wish I had done now!

 

[PSH]

I didn't do the belts on the 944 as I wanted the stamp in the book, kind of wish I had done now!

well the advantage of getting a specialist to do the belts is if they mess up they are covered by their own insurance to make good where as your not, but it's not rocket science as they say...[]

and yes 10mm over longest span , it's worth checking with a feeler gauge over the roller as Porsche say... 0.5mm I believe is the gap.. if it touches then it's too tight

Pete

 

[awattam]

ORIGINAL: PSH

I didn't do the belts on the 944 as I wanted the stamp in the book, kind of wish I had done now!

well the advantage of getting a specialist to do the belts is if they mess up they are covered by their own insurance to make good where as your not, but it's not rocket science as they say...[]

and yes 10mm over longest span , it's worth checking with a feeler gauge over the roller as Porsche say... 0.5mm I believe is the gap.. if it touches then it's too tight

Pete

Thanks, I'll check both belts and hopefully adjustment won't be necessary. The whine isn't bad but still audible inside the car when it's cold. It's the sort of thing I'd rather check with my own eyes as the consequences of failure are damn exensive! Actually the belts on the 944 look a hell of a lot easier to change than on most front wheel drive cars where the engine mounts/inner wings are in the way.