Our 2001 Multipla 1.6 petrol has started making an awful screaming noise on acceleration. It is not linked to engine speed or road speed just when I press the accelerator, I can control the pitch of the scream by how hard I press the pedal. No noise at tick over or on over run.

I am now baffled, please help. Many Thanks

Usually screaming noises like that will be a belt on it's way out, you've only got 2 I believe - alternator and cam. Might be worth posting directly in the 'Multipla' section though for more answers.

If the alternator bearings seize the aux drive belt will squeal. The other option is water pump bearings but that is driven by the cam belt. If the cam belt is failing, you wont hear anything before the engine stops with bent valves.

If the alternator belts is old there is a good chance the cam belt will also be old (its convenient to replace both at the same time). If there any doubt about the cam belt's age or miles change it before its too late.

First check is to see if the alternator bearings are failing. If OK the water pump is the next place to look = replace cam belt and tensioner at the same time as the pump.

I managed to sort it today, I checked belts etc but elimated them from the list. It turned out that the back box was blocked with it's internals trying to come out of the tail pipe. I presume the gases from the engine where coming back up the exhaust and meeting new gases, they where squealing out of the joint between the cat and link pipe.

I have temp fixed it by forcing a flexi pipe up the tail pipe to free it up, the engine pressure forced a load of fibres out and the engine suddenly sounded alot healthier, it feels like I have just fitted a turbo to the car, the difference is amazing.

A new back box is on the cards this week. thanks for your help on this.

it's probably worth having a cat back system as the front box might not be much healthier inside.