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Hi guys,
I'm gnna get this checked by a mechanic, but want to see if anyone knows what it is!
I recently just got all my water pumps replaced and got the AC fixed - got the car back today.
I noticed when i turned the car on there is a weird "humming" sound inside the car and it changes pitch with engine revs.
When i turn the AC on (at idle) the noise seems to dissapear.
Bit of background: the water pumps in my car have always been faulty and i dont think coolant has ever sorta been pumped 'round the engine and stuff correctly since i bought the car in Feburary and also the AC has always been "faulty" - as in its worked but was noisey (i think a bairing or something went and caused it to make screaming noises -lol).
So i dunno if this noise is "normal" for the polo or if something has indeed broken (again!)
Re: weird humming noise
Posted: Wed Dec 20, 2017 7:52 am
by RUM4MO
I'd think that that car only has a single water pump that is driven directly by the cam belt, it has been known for the water pump impeller to break free from its axle/shaft and so stop pumping the coolant round the system, if that was what had happened, I'd hope that your garage replaced the cam belt and all the associated idlers/pulleys and tensioner as it makes no sense to be "working in that area" and not do all these associated tasks which these cars with that engine need replacing every 5 years ??K miles. So anything original left in there could be causing that noise, and switching on the AC is just loading the engine enough to get rid of that noise or by changing the revs slightly.
AC faulty, "bearing gone" - only one bearing in the AC system is that is inside the compressor, well maybe two bearings in that compressor, in a local garage, any issues with a compressor would mean that they simply replace it with a "good" used one or buy a reconditioned one from some sort of source, or buy a new one.
Do you have a bill to outline exactly what they did do to your car and what was the cost of the parts used and the description of them?
Edit:- other possible source of noise in there is the alternator, but as you have said the noise remains as long as the AC is off at all revs, I'd reckon that the noise is coming from the compressor currently fitted into that car - so you must find out where it was sourced from as it might have been a sort of good but used one, a new one, by its self, would cost you roughly £500, so see if that ties in with what you have been charged for that part and really you need to get it back to them to sort out properly.
Re: weird humming noise
Posted: Wed Dec 20, 2017 7:10 pm
by gaza1994
RUM4MO wrote: Wed Dec 20, 2017 7:52 am
I'd think that that car only has a single water pump that is driven directly by the cam belt, it has been known for the water pump impeller to break free from its axle/shaft and so stop pumping the coolant round the system, if that was what had happened, I'd hope that your garage replaced the cam belt and all the associated idlers/pulleys and tensioner as it makes no sense to be "working in that area" and not do all these associated tasks which these cars with that engine need replacing every 5 years ??K miles. So anything original left in there could be causing that noise, and switching on the AC is just loading the engine enough to get rid of that noise or by changing the revs slightly.
AC faulty, "bearing gone" - only one bearing in the AC system is that is inside the compressor, well maybe two bearings in that compressor, in a local garage, any issues with a compressor would mean that they simply replace it with a "good" used one or buy a reconditioned one from some sort of source, or buy a new one.
Do you have a bill to outline exactly what they did do to your car and what was the cost of the parts used and the description of them?
Edit:- other possible source of noise in there is the alternator, but as you have said the noise remains as long as the AC is off at all revs, I'd reckon that the noise is coming from the compressor currently fitted into that car - so you must find out where it was sourced from as it might have been a sort of good but used one, a new one, by its self, would cost you roughly £500, so see if that ties in with what you have been charged for that part and really you need to get it back to them to sort out properly.
i took a video of the noise
It's going into the garage tomorrow night to get a professional ear on it!