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Technical TJet drive/alternator belt squealing, sparking and smoking

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Technical TJet drive/alternator belt squealing, sparking and smoking

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dmorrison134

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Hi , new to the site. Have Fiat Grande Punto.Tjet 57 plate 94000 miles.

When I start up the car, either the engine starts then it starts squealing before it cuts out or it’s starts squealing and a bit of throttle keeps it going but the drive belt starts smoking and sparking. The sound is coming from the belt to the left of the engine. The tension in the belt seems okay can get almost 90 degrees of turn in it.

Does anyone know what this is? Tried to upload video but showing invalid

Background:

My car had some electrical problems some weeks ago (involving one where the engine kept running after removing the ignition!) . I have since replaced the fuse box and the battery and the electrics seem to work again but cannot get car to start properly now without This squealing and smoking
 
Theoretically if you’ve shorted the alternator the short could act like a big resistor and effectively turn the alternator into a big emf (electromagnetic brake) which the faster you turn it the more it resists.
So it might turn ok by hand but spin it faster like the engine does and it will resist being turned.

I’d definately might be temped to electrically disconnect the alternator and try and start the car to see if it all spins ok.

If all is well then pay close attention to connecting it back up, then trace all your wiring to make sure nothing is shorting to ground
 
Aaaahhh, Charlie, Andy and Nick !

All of them very active and (almost) always right with their troubleshooting !! Hat-off gentlemen, I can only agree with your statement regarding the alternator...

But, IMO, electrically speaking the alternator should not "brake" more than it's maximum output: 40A x 14V = 560watts or about 3/4hp. So smoke comes probably from a slipping belt and sparks from a mechanical issue, like the iddler or tensioner.

I'd remove the accessories belt and check if one of those is seized/hard to hand turn...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)
 
This did not happen before I replaced the fuse box (there was water in the old one and the electrics went kaput and killed the battery, which was very old anyway)

The old fuses are intact and the connectors have since dried out. Do you think it’s worth popping the old fuse box back in ?


Additionally in this attached photo, does anyone know what this component is that the drive belt is around? There is sometimes smoking and sparking coming from the back of here
 

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NB, seen on a car parts site that is the air con compressor. Perhaps that is having a problem rotating, putting strain on other elements of drive belt
 
As Bernie has suggested try taking the belt off and check for seized bearings etc..its a quick and simple check.
IF your confident the old fuse box is now ok the swop it back and see..fyi I have no idea how long that would take to do. Is it a big job?:confused::confused:
 
Last edited:
Pic shows the aircon compressor.

There are several potential issues. You have seizure or partial seizure of one or more of teh following.

Alternator
Idler or tensioner pulleys
Aircon compressor

The tensioner pulley is sprung, quite fiercely. It is released with a spanner acting as a lever. Use the longest spanner you can find, for best leverage, and keep fingers out of anywhere they can be trapped if you let go.
 
Alternator seizure is common from the old type scuttle drain drains off water directly onto the alternator therefore corrosion developing and seizure, normally belt squeals then smoke.

To confirm as above pull aux belt off and spin all your pulleys, if its alternator i would get a new one, with belt and tensioner and modified scuttle drain to prevent it again in the future
 
Not sure how Punto's AC compressor are, but some of them have fixed output (no variable volume) and therefore need to be dis-engaged when AC is not requested.
To do this, there is a magnetic clutch built in the pulley that manages the coupling/decoupling with the compressor shaft.

Maybe the 'new' fusebox isn't compatible with you car, or the old one couldn't switch the AC on, or more simply the AC wasn't turned ON !

Anyway, if the compressor is (partially) seized and the clutch is now engaged for either reason, the belt would slip and smoke and the clutch sparks ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)
 
dmorrison134 said:
Hi , new to the site. Have Fiat Grande Punto.Tjet 57 plate 94000 miles.

When I start up the car, either the engine starts then it starts squealing before it cuts out or it’s starts squealing and a bit of throttle keeps it going but the drive belt starts smoking and sparking. The sound is coming from the belt to the left of the engine. The tension in the belt seems okay can get almost 90 degrees of turn in it.

Does anyone know what this is? Tried to upload video but showing invalid

Background:

My car had some electrical problems some weeks ago (involving one where the engine kept running after removing the ignition!) . I have since replaced the fuse box and the battery and the electrics seem to work again but cannot get car to start properly now without This squealing and smoking
Click to expand...

How did you get on in the end diagnosing this issue mate?
 
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