Belt thrown - My 2002 4.4i currently a Non runner

[AW8]

My car currently RAC recovered on my drive pending it's arranged flat bed delivery to Richard at Barkers Motor Works next week.

On Tuesday evening I was driving & noticed a slight smell of burning & rubber. Pulled over & could hear main engine fan seemingly labouring & with noise as fan was rubbing. Engaging gearbox to D resulted in car stalling & accompanied with high pitch belt or bearing failure noise.

Got car recovered home. Yesterday in daylight some noise but belts seemed intact. Engine noise louder than usual caused me to suspect timing chain or maybe vanos issue. I revved engine to 3.5k or so and it totally threw the main front pulley belt that runs around alternator, water pump and fan pulleys.

Alternator & bearings/pulleys appear to have free movement without excess play.

No coolant loss or sign of water pump, (new in last 15k), leaking.

No visible damage to fan or fouling  by pipes.

So possible issues are.........

(i) Seizure / bearing issue(s) for alternator, water pump, main fan.

(ii) Crank pulley issue associated with engine  possibly due to a worn timing chain slip  :'(

(iii) Belt failure only..........but belt only fitted in last 15k miles.

(iv) Something else.

Initially at roadside I suspected a gearbox issue, (as it stalled when put into D) . I doubt that it's box now but this could still be a big bill.

I may remove the chewed belt but I can't easily check for crank movement if engine non runner.

Will give further update once Rich & team look at it.

In meantime if anyone has sensible ideas then I will be interested to read them.......

[X5Sport]

If it was timing would you have been able to rev to 3.5k?

Seized alternator should have brought the battery warning light on.

Water pump or fan pulley bearing (is that fan on a viscous coupling?) would seem the most obvious though I can't see why engaging 'D' would make a difference unless it was just coincidental timing with the failure.  It needs a lot to stall a big engine.

If the replacement belt was fitted to tightly then that could cause premature issues with both the belt and any rotating components along it's 'route' so to speak.  Smell of burning rubber would point as you surmise at one of the three items mentioned having stopped playing.

[AW8]

Thanks for the prompt & valued reply.

I am leaning towards the main crank pulley/bearing failing albeit the rattle noise at top of engine prior to belt failure concerns me.

No warning lights or dimmed lights pointing to alternator prior to belt thrown and I seemingly have smooth free movement in bearings.

Incorrect belt tension could be a possibility.......thanks for thoughts

[X5Sport]

It's just possible the incorrect belt tension could have been causing the timing chain tensioners to work harder and you could hear the chain system complaining if a small excess of chain slack was being generated that the tensioners could not handle and you could hear a bit of chain 'slap' or 'rattle' against them?

R

[AW8]

A possibility perhaps.................I will leave it alone for now as Rich will get paid to do the dismantling but I will post update in due course & after car goes into workshop on 10th.

[ChrisLux]

Just had the same problem on the B8 .

It was a faulty belt tensioner . The tensioner let the belt slip off , which then wound itself
around the fan blades , snapping all of them off , 2 went throught the radiator and one left
a nice big dent in the underside of the bonnet .








End result ; new radiator , 2 new tensioners , new water pump , new pulley , new fan and
viscous coupling (which is what I thought originally had failed) , new belt and other smaller
items . Damage , €1400 for a part that costs €40 !!

[AW8]

Hmm...........not good.

In absence of me stripping everything down I will have to wait to learn what has been damaged albeit I cant see any visible signs other than belt wrapped around the main fan coupling.

Already wishing I had left it as it was.................i.e. poorly but running.

When I asked old indy to change water pump & aux fan,  (a couple of years ago), I asked that stat, plus various hoses, rings, clips & belts were replaced at the same time. Ironic I fell out with that indy when they took issue with me calling more than once to cross check parts subject of preventative maintenance.........I have not used that indy since.

[ChrisLux]

[quote="AW8"]
Ironic I fell out with that indy when they took issue with me calling more than once to cross check parts subject of preventative maintenance.........I have not used that indy since.
[/quote]

I'd have said at least that's better than turning up to collect the car and find a bill of £1000 !! though .

The Indy I use in Wolves , called me several times when the X5 was in at Easter . OK , not always convenient
but can't knock them as they're very good .

[X5Sport]

There was a 5 series in the Dealership whilst I as having the tyres done and it had hit a brick which had gone under the car.  It had taken the sump out - possibly damaged the block/crank bearings, gearbox base and damaged the diff all in a couple of seconds.  The bill was £4k just to strip it to find out how bad it really was!!

There were an awful lot of bits on the floor around the car and the engine in a cradle.  Insurance job!!

Richard

[AW8]

Delay sorting this due to part sourcing.

PAS pump case seems to have failed...........It needs PAS pump, new alternator, (bearings shot), plus new serpentine belt and tensioner.

Hopefully will be sorted before end of next week

[Black X5]

So it is both issues that occured together or did the PAS pump case fail due to damage from belt coming off? (due to failed bearings in alternator siezing up?)

[AW8]

I have no idea. I had power to steering initially then ran it on drive to check-diagnose once recovered. I suspect the alternator may have seized and in turn the belt threw and cooked the PAS pump - however I switched off engine as soon as the belt threw...............the PAS pump casing has completely broken.

Delay as salvaged PAS pump was wrong - even though from a pre-facelift V8 it was a ZF item as fitted to 7/02 onwards cars whereas my 12/01 build has a Lux branded pump. Correct item should be with indy tomorrow or early next week - I hope its correct as list price from BMW for one of these is £700 before discount. 

[shadrack]

ouch n ot what you need although a lot cheaper than a gearbox

[storminmike]

Makes my recent headache with the tracking positively pitiful.  Good luck on getting it back the road

[shadrack]

glad I sold mine lol