Crankshaft pulley and sensor

[Ereinan]

Hello.
The last few weeks i have noticed loud rattle from the passenger side of the engine bay (drivers side in UK) and had planned on replacing crankshaft pulley and aux belt in the near future (after new winter tyres). But now, however, I am faced with a new problem. The last few days I have noticed that the speedometer drops to zero for a while and then comes back to life again (a small performance change is then noticed). After some research on the net i have perhaps found this to be the speed sensor (crankshaft sensor?).

But I wondered now, can these faults be somehow related??

[steve_earwig]

Firstly, if the crank pulley drops the aux belt there's a good chance it'll take out the cam belt with it. Not necessarily terminal but it will probably need all 8 cam followers replacing. And the cam belt of course, plus tensioner, water pump...

Speed sensor (crankshaft sensor - no) is on the gearbox, the drop in power is because the engine ecu assumes you are stationary and just revving the engine.

I seriously doubt the two are related...

[OdinEidolon]

Firstly, if the crank pulley drops the aux belt there's a good chance it'll take out the cam belt with it. Not necessarily terminal but it will probably need all 8 cam followers replacing. And the cam belt of course, plus tensioner, water pump...

Speed sensor (crankshaft sensor - no) is on the gearbox, the drop in power is because the engine ecu assumes you are stationary and just revving the engine.

I seriously doubt the two are related...

What Steve said. How loud rattle? Can you hear it from inside the car?

[Doggy]

[Ereinan]

Thanks for replying
Yeah i know, but the wallet havent been in top form recently and I have just keep pushing it before me Its not really noticeable inside the car, sounds like a diesel to me. But outside its really easy to pinpoint where the sound comes from (passenger side).

So the speed sensor is the one i can se just below the air filter box and the maf. On the top of the gearbox, slightly towards the rear?

[jetdoc3]

I have had vibration damper failure same sort of symptoms if you look carefully with a torch and you can see swarf down around the pulley area then this can cause the rattle. The other rattle causer I have experienced is the aux drive belt tensioner try sprinkling a bit of talcum powder around the aux drive belt while the engine is running if the rattle changes or decreases then this could be your man.

[jetdoc3]

Crankshaft position/speed sensor is on the top of the bell housing right next to the block under the air filter housing, vehicle speed sensor is on the gearbox final drive and MAF sensor is the big sensor just downstream of the air filter housing. cheers

[martint]

You'll need to get it up on a ramp mate,cos the hassle o getting to it,when cars jacked up is unbelievable! You'd need to be a contortionist! They're made o a White plastic material so easily seen,with the connector at the top. There's no way I would've got mine out but for a ramp.