Idler Pulley Noise

[Stanky]

Possibly 'stupid question amnesty' fodder, but does anyone know the answer to this.

 

I believe the whining noise that the Saab is making is the idler pulley bearings on their way out, its a variable pitch whine based on engine speed but investigation this morning confirms its coming from that area and isn't the turbo or gearbox, which is comforting.

 

The serpentine belt drives the alternator, water pump, a/c compressor and PAS pump, if the idler seizes then the best shreds and I lose all of these - nothing immediately catastrophic but certainly inconvenient.

 

I have a 400 mile drive to undertake at the weekend, how foolhardy would I be to take the Saab? it is a lot nicer to be in than the Nissan for a long journey, but I'd rather not have the fun* of the belt shredding on the M25 and having to be recovered home. This journey will be made with my wife and daughter who will be unimpressed if the above happens.

 

The car is booked in at a local garage for investigation and I suspect that they will confirm my diagnosis and fix it, but thats not until next wednesday. The noise hasn't got noticably worse in the last 2000 miles since I began to notice it, and to be honest has probably been getting worse for several thousand before that. You can't hear the noise above 40mph due to road/wind noise so I don't think its in immediate danger of snapping but what do others think?

 

Should I risk taking the Saab or slum it in the Nissan which is less comfortable but guaranteed to make it there and back intact?

[SiC]

What engine is in the Saab?

 

If 1.9TID, then could be the waterpump bearings on its way out - a common problem. If so, as its attached to the cambelt, then it would be a very good idea to get it fixed before it completely shreds the belt.

[Stanky]

1.8t (150bhp) pez, so its a cam-chain and I don't have that to worry about - just loss of drive to the ancilliaries.

[SiC]

Are you sure the water pump is driven by the belt?

 

According to WIS (Workshop Information System), its:

The centrifugal coolant pump is located on the left-hand side of the engine and is driven by the crankshaft via the balancer shaft chain circuit.

also quite interestingly:

The coolant pump sprocket also serves as an idler wheel for the balancer shaft chain. This is to get the balancer shafts to rotate in opposite directions.

If so, I guess risk of engine damage is minimal. Just family trust level could be dented.

[SiC]

Just to add this nice little diagram:

 

Personally I don't know if I'd take a risk if you don't want to be stuck by the side of the road, unless having a good look at the state of the tensioner first. If its the bearings breaking up, then it could go at any point and fairly rapidly disintegrate. But then if its been doing it for a while and not got any worse, then it might be alright for a bit while longer.

 

Actually thinking about it, I'd probably take the Saab because its so much more comfortable and take a punt...

 

EDIT: To replace the tensioner, according to WIS, you take the wheel off and remove the right wing liner. Belt tensioner wheel bolt is 25nm, belt tensioner itself bolt is 50nm. Looks a fairly easy+straight forward DIY job tbh.

[sierraman]

Idler usually sounds like a slightly rough dry bearing whirr. Best description I can give.

[Stanky]

Thanks SiC, I think the engine damage chances are minimal (assuming I've correctly diagnosed it) but I'll never hear the end of it if it does shit itself and we get stranded.

 

BTW the piccy hasn't linked properly, can you re-add it?

 

Sierraman, it sounds like an electric drill on low speed, thats the best way i can describe it. Almost quiet at idle, but noticable at 2k RPM in 1st and 2nd (its an auto)

[SiC]

Hmm, works fine here, maybe a browser issue.

 

I'll try as a JPEG...

[sierraman]

Could be the belt as well. Daft as that sounds. I'd get a new belt if it's glazed, then whilst it's off thoroughly spray the tensioner with penetrating fluid, easing it off against the return spring. Spin the bearing, if it's rough then replace it. Check the other pulleys while you are at it.

[Stanky]

SiC, thanks - works fine now. Probably a browser issue my end.

 

Yes, thats what it looks like from the top, I think #2 needs replacing based on my research, though to be fair it could be the bearings on 1, 3 or 4 potentially too. Apparently the tensioner has a 60k lifespan and its at about 55k now so probably due for changing regardless. Good to know the water pump isn't driven by the belt, one less thing to worry about.

 

I'll have the garage inspect the whole lot, I think a new belt and tensioner are a minimum, plus a good check of the alternator pulley and A/C too - they are a Saab specialist so ought to know what they're doing.

 

I'll have a think about it and talk to SWMBO.

[The Reverend Bluejeans]

When doing a belt change, I always pick the circular seals from the pulleys and regrease them.  They always live again - esp. expensive ones.

[Stanky]

Turned out the alternator bearings were past it, got the alternator, belt and tensioner replaced today for £240 all in.

 

The chap at the garage turned out to be a decent sort, he poked about, called me with the diagnosis and said a new alternator was £240, or he had a second hand one which seemed ok but he couldn't warranty for obvious reasons which he'd sell me for £75. I went with the latter option, and asked him to change the belt and tensioner anyway since he had it all in bits anyway.

 

For good measure I checked ECP and as a punter I'd pay £262 for an alternator, plus and £80 surcharge refundable* at some point long after I'd taken the old knackered one back, so its not like he's even diddling people on parts costs.

 

Overall I'm pleased, the chap seems an honest sort, the car is now silent and I know that 2/3rds of the aux belt system is new. I'll keep an eye out for another secondhand alternator as I don't know the history of this one, but its a lot quieter than the old one! I'll definitely use them again for jobs that I can't do myself.

 

Oh, and I bailed and took the Nissan at the weekend, it dispatched 500 miles with the three of us and various tat on board easily. Gave the gearbox a good shakedown too and that seems to be great too.