Hello

Recently my 0.9 Twinair 500C Automatic has started to squeak a little.
The squeaking comes and goes, but I think it is from the accessories belt (if you rev it up, the squeak becomes more prominent, then as it idles, the squeak slowly fades away).
It was serviced a short time ago, and I am wondering if it is possible that the mechanic failed to lube something during the service that would have stopped the squeaking?
Is there an obvious grease/lube point that needs to be lubricated during the annual service that may have been missed, causing the squeak?

Thanks in advance.

Manny500C said:

Hello

Recently my 0.9 Twinair 500C Automatic has started to squeak a little.
The squeaking comes and goes, but I think it is from the accessories belt (if you rev it up, the squeak becomes more prominent, then as it idles, the squeak slowly fades away).
It was serviced a short time ago, and I am wondering if it is possible that the mechanic failed to lube something during the service that would have stopped the squeaking?
Is there an obvious grease/lube point that needs to be lubricated during the annual service that may have been missed, causing the squeak?

Thanks in advance.

Click to expand...

No, you could simply replace the belt or remove it start the car and see if the noise is still there, if not just replace it?

Ok...so I had the accessory belt changed during the last service, but there is still a squeak from the engine bay after a bit of driving on the highway. What I have noticed is that the squeak stops when the engine is idling and I turn on the air conditioning. So something related to the air conditioning system (whether a belt, pulley, bearing, or something) is related to the squeak. Does this clue assist to diagnose the problem?

It's probably the aux belt tensioner or upper guide wheel.

The tensioner is spring loaded and directly behind the alternator. (belt goes over the small black pulley wheel)

The upper guide wheel is fixed and is above it, just behind the air con compressor. (small black pulley wheel that the belt goes under)

You can see them here
https://www.flickr.com/photos/fiat/5038719032/

If you can get in there, a squirt of WD40 or similar on these pulley bearings (don't get it on the belt) might shut it up a while and help identify the problem, though it will eventually come back again as the bearings really need greasing.

Hi Goudrons, thanks for that suggestion. So when I turn on the air conditioning, does that change the rate of spin of these two possible culprits, causing the squeak to stop?

Also... If it is one of these two things, is the squeak a warning that one of them is about to fail and leave me stranded?

Thanks again

The squeak is probably not the belt, if a new one has failed to shift the mice in the works.

You really need to remove the alternator belt and find the source of the squeak.

The belt presumably drives the alternator and the air-conditioner pump (I guess 500 power steering is electric) and it will have a tensioner and possibly an idler pulley in there too.

The tensioner and idler can be easily unbolted once the belt is off and lubed to buggeration.

The alternator and the air-conditioner pumps are more tricksy. They will each have a pulley that runs on needle bearings... and the a/c also has an internal clutch. Any or all of these might be worn out or just need some grease, although they're supposed to be sealed so aren't lubricated as a service task.

Spin the pulleys by hand and see if you can make them squeak. Also check for any twisting movement in the pulleys (it should not be possible to move the pulleys at all.. although some miniscule "in/out" movement might be okay. If you see any red powder around the bearings.. that's the culprit.

I'd focus on the a/c since the squeak stops when that's on... although when a/c is on that will put a load on the belt and that extra load might make a squeaky alternator pulley go quiet. If I was betting on it.. I'd go for the alternator since it's behind the engine at the back of the engine bay. It's probably hotter there than next to the exhaust manifold.

Anyway.. if anything squeaks or moves, lubricate it. Use some WD40 type of spray but also apply some grease. The WD40 will evaporate after a few days but while it's there it will dissolve the lumps of grease you've left there and carry it into the bearings.

The less good news is that any movement or red powder on the pulleys means that the bearings are packing their bags for Boot Hill. I'd start to budget for a new "whichever". You may be able to replace just the bearings but compare prices of bearings plus labour with "new whichever". There's not often a big difference, if you consider that the part (e.g. alternator) will be all new, rather than your old one fitted with new bearings.


Ralf S.

Manny500C said:

Ok...so I had the accessory belt changed during the last service, but there is still a squeak from the engine bay after a bit of driving on the highway. What I have noticed is that the squeak stops when the engine is idling and I turn on the air conditioning. So something related to the air conditioning system (whether a belt, pulley, bearing, or something) is related to the squeak. Does this clue assist to diagnose the problem?

Click to expand...

Hi,
If it reliably stops when you turn the AC on its likely to be the AC compressor pulley/clutch. The pulley on the AC compressor has a electromagnetic clutch in it, when de-energised the pulley turns but the compressor shaft doesn't. When engaged they are locked together. If the bearing is dry it can squeak when the AC is off. If AC is on there is no relative movement and noise will stop. Note that the compressor can be switched off when running so noise may come and go even when AC selected on, but if set to max it should stop.

Robert G8RPI.

Great suggestions from everyone. Thanks to all. I am much more confident now that the problem will be solved.