Hi guys, new to the forum and after some advice please. Now I'm no mechanic so take it easy with the jargon please

I have a Y reg TD4 auto

Recently had a rattle coming from the engine so took a look under the bonnet and found some bits of rubber and an obviously worn belt.

Took it to my local garage expecting them to replace the belt and perhaps a tensioner pulley (had this before on another vehicle). Bit suprised when they called to say it was ready, new belt fitted but the noise was still there and they couldnt work out what it was.

Needless to say I took it somewhere else but on the way the noise dissappeared! All was quiet for the next couple of weeks.

On pulling away from a junction one day I had no power steering. Remembering somehow that the AC runs off the same belt (?) I turned it off to find I now have power steering again! On closer inspection I found that if I turned the wheel with the AC on it actually stops the belt!

Spoke to a mechanic who advised that the AC pump may be seasing up.
Apparently the unit costs £480 before fitting - gulp! The rattle is now getting a bit worse (on idle) and Im sure I felt the engine being slowed by the belt.

Burning question - is there a way of by passing the AC pump, perhaps with a shorter belt?? I have heard of this done on a VW. I can live without the AC (as the wife drives it!) and the expense.

Any advice greatly appreciated

best introduce yourself moosh

What colour is it?

engine/gearbox?

When air con is off, the air con compressor pulley spins free. If not, then the clutch on the air con compressor is stuck, me thinks. When air con is on, air con compressor clutch closes and pulley turns the bits inside (the air con compressor).

take the wire of the switch and then the wife will not switch it on until you have a new aircon unit

unless she sets the vents to demist / screen then the aircon will come on automatically.

pull the fuse ?

Pull the wire off the compressor there's only one it's easy to find!

Ac runs on a separate belt iirc so most likely to be crank pulley failing- the damper part fails allowing the outer part to stop spinning.

As pointed out there are 2 belts , Short one for AC & long belt for all the rest .
They should last 10 years or 96000 .
Mine was replaced at 12 years & 70000 belts were cracked , My problem was a blocked pipe somewhere in the AC making the pump noisy .

Hippo said:

What colour is it?

engine/gearbox?

When air con is off, the air con compressor pulley spins free. If not, then the clutch on the air con compressor is stuck, me thinks. When air con is on, air con compressor clutch closes and pulley turns the bits inside (the air con compressor).

Click to expand...

BMW diesel unit so I'm told - auto box and its er.....green! Does the colour affect the outcome?

I have now discovered that with the AC on, if I turn the wheel the belt stops! I am sure I have felt the engine being slowed even with the air con off. There is a clattering noise which seems to be getting worse, mainly when idleing.

If the ac is on a separate belt remove it and see what happens!

the tensioner on the belt may not be doing it's job

As suggested, i would check out the crankshaft pulley damper - that rattles like hell when it's on its way out and is a relatively cheap and easy fix. Mine made a hell of a racket when it went and on the way to the garage my air-con and alternator were playing up (obviously - since both belts go via the crankshaft pulley).

the ac does have a seperate belt I would not think it was the crank pully or he would know about it with the sound of a lawn mower under his bonnet the second belt for the air con is behind the main one so just taking this air con of would be a no no unless you take the big one of first and that is a case of getting a 24 mm ring spanner ( flat spanner will slip off) for the tensioner of the big belt the aircon one is a small spanner job