High pitched whine from the vicinity of the auxiliary belt

[Philip Fisher]

A high pitched whine started this morning on my T8. Definitely engine rev related and when I opened the bonnet it seems to be from the auxiliary belt (or something it is driving) on the drivers side of the engine bay. More noisy on tickover, reving the engine a bit makes it disappear. Any ideas? Likely to be the belt, or something it is driving? Any quick solutions?

Thanks in advance

[Lexman8]

Iirc the power steering, aircon compressor and water pump are all powered electrically on a T8 so that just leaves the alternator being driven by the engine.

The fact that it's engine rev related would appear to point to the alternator or its belt.

Not much help but perhaps turning off the aircon would eliminate the compressor as a source of the noise?

Also, I assume that there's only one water pump for both engine cooling and for the aux heater so turning on pre-heat might reveal the pump as the source of noise?

EDIT: Does a T8 even have a conventional alternator? I think it probably does as energy recovery is presumably achieived via the rear motor.

[Philip Fisher]

Originally Posted by Lexman8

Iirc the power steering, aircon compressor and water pump are all powered electrically on a T8 so that just leaves the alternator being driven by the engine.

The fact that it's engine rev related would appear to point to the alternator or its belt.

Not much help but perhaps turning off the aircon would eliminate the compressor as a source of the noise?

Also, I assume that there's only one water pump for both engine cooling and for the aux heater so turning on pre-heat might reveal the pump as the source of noise?

EDIT: Does a T8 even have a conventional alternator? I think it probably does as energy recovery is presumably achieived via the rear motor.

Thanks Lexman. As I understand it, the T8 has a starter generator which is mechanically connected. I have also always thought this to be the large box with the orange 400v connectors on the passenger side of the engine bay, but I might be wrong.

I also understand power steering to be electrically driven and ac too. Which leads me to wonder what exactly is being driven by this aux belt? There is definitely a belt in this area and it is definitely where the noise is coming from. It also runs round some pulleys but I cannot see any more. I wonder if it is just the engine water pump off this belt? I am assuming the belt I can see will not be the cambelt as the cambelt would always be under a cover? Besides this belt does not come to the top of the engine so it cannot be the cambelt.

Aircon was off when I heard it this morning, I will try pre conditioning and just listen to rule out that, but it is looking increasingly like the belt. Would spraying the tiniest bit of silicon spray on it get rid of the noise or just make it slip like crazy I wonder?

[Tony H]

I get a high pitched whine from the passenger seat area.....

But it stops when the wife gets out!!!

Sorry - I'll get my coat!

[Philip Fisher]

Originally Posted by Tony H

Sorry - I'll get my coat!

I think she might get it for you.....

[rhd443]

Originally Posted by Philip Fisher

Thanks Lexman. As I understand it, the T8 has a starter generator which is mechanically connected. I have also always thought this to be the large box with the orange 400v connectors on the passenger side of the engine bay, but I might be wrong.

I also understand power steering to be electrically driven and ac too. Which leads me to wonder what exactly is being driven by this aux belt? There is definitely a belt in this area and it is definitely where the noise is coming from. It also runs round some pulleys but I cannot see any more. I wonder if it is just the engine water pump off this belt? I am assuming the belt I can see will not be the cambelt as the cambelt would always be under a cover? Besides this belt does not come to the top of the engine so it cannot be the cambelt.

Aircon was off when I heard it this morning, I will try pre conditioning and just listen to rule out that, but it is looking increasingly like the belt. Would spraying the tiniest bit of silicon spray on it get rid of the noise or just make it slip like crazy I wonder?

Just drop some water (or spray from a handheld pump spray) or tip a little bit onto the belt when it's spinning from a milk bottle, water won't damage it and will silence any belt squeaks if that's the cause. Old known mechanics trick.

You have an older T8, isn't the supercharger also belt driven and always spinning? Might be worth checking with a long screwdriver and put your ear to the handle against the metal engine block to see if you can hear any bearing noises.

[Philip Fisher]

Originally Posted by rhd443

Just drop some water (or spray from a handheld pump spray) or tip a little bit onto the belt when it's spinning from a milk bottle, water won't damage it and will silence any belt squeaks if that's the cause. Old known mechanics trick.

You have an older T8, isn't the supercharger also belt driven and always spinning? Might be worth checking with a long screwdriver and put your ear to the handle against the metal engine block to see if you can hear any bearing noises.

Ah, supercharger, hadn't thought of that. B***er, that will be expensive if it is that. I will try the water trick tomorrow and report back.

It is a funny whine. It is only there between tickover and maybe 2k revs, then it disappears. With the T8 engine switching on and off frequently you tend to hear it before the engine shuts down. It does kind of sound like a dry bearing as the noise dies away, but more like a belt squeak when it is louder. It is also very consistent, which is leading me to thinking that it is something that is driven by the belt rather than the belt itself.

Will report more tomorrow.

[Philip Fisher]

Put some drops of water on it but no change to the sound. Someone at work suggested there will also be a belt tensioner there which will have a bearing in it. He agreed with me that it sounds like a dry bearing.

My friendly dealer have offered to take a very quick look tomorrow at 8.30am. Fingers crossed......

[Philip Fisher]

Stopped by my friendly dealer on my way to work this morning and the master tech took a look and listen at the noise.

He put his worried face on. "I don't want to worry you but.......".

So he thinks it could be a number of things, including possibly the balancing shafts which he has seen on another car. He was keen that I drove it as little as possible until they have had chance to diagnose it.

I am due to drop it off tomorrow pm and pick up a courtesy car (earliest that they had a car) and they will start a proper diagnosis. I have left it at work tonight and come home in the hateful pool car (2019 Corolla), didn't want to risk another 100 miles on my car.

I will report back when I know more. I was just thinking it had been very reliable for the last 2 years and 30k miles since the electric motor was done. Still let's hope this isn't worst case.......

[Moomoo]

Originally Posted by Philip Fisher

Stopped by my friendly dealer on my way to work this morning and the master tech took a look and listen at the noise.

He put his worried face on. "I don't want to worry you but.......".

So he thinks it could be a number of things, including possibly the balancing shafts which he has seen on another car. He was keen that I drove it as little as possible until they have had chance to diagnose it.

I am due to drop it off tomorrow pm and pick up a courtesy car (earliest that they had a car) and they will start a proper diagnosis. I have left it at work tonight and come home in the hateful pool car (2019 Corolla), didn't want to risk another 100 miles on my car.

I will report back when I know more. I was just thinking it had been very reliable for the last 2 years and 30k miles since the electric motor was done. Still let's hope this isn't worst case.......

🤞🙏 and anything else you can think of!