Periodic (horrific) noises & braking effect

[Linds]

I have a two and a half year old Mk 3.5 1.5 TDCi with a manual 6 speed gearbox coming up to its 37.5k service.  The car has been a dream to drive and I love it dearly.

However ... once every 3 months or so, always when travelling below 30mph, it suddenly emits a quite horrific noise and appears to brake.  Depress the clutch and the noise stops immediately  ... select another gear and the car proceeds happily on its way.

Before continuing I should say I am an oldish driver with lots of experience of cars with manual gearboxes ... I have occasionally driven up to 50k miles per year ... now the annual average is closer to 18k.  My last car was a diesel Audi A3 which I owned from new and sold with 150k on the clock after about 8 or 9 years.

I will attempt to "define" the horrific noise - it is NOT crashing gears!  I know what they sound like and, simply put, I don't crash my gears!  If you can imagine sticking your foot (encased in a steel tipped boot) into a bag full of loose metal tools (spanners and the like) and moving it about violently, the noise is probably akin to that.  When I first heard it I thought I had shredded the engine - the noise is that loud and unpleasant.

So when does it happen?  Well it happened once when edging forward at a snail's pace into a tight parking space.  Then in traffic once there was a chap dicking about in his BMW (as they do) ... I went to overtake ... was halfway through the manoeuvre when suddenly noise happened and the car appeared to brake ... so I had to abort the overtake.  Most embarrassing!  More recently I was in a flow of slow moving traffic and, again, sudden noise and apparent braking effect.

I have told the dealer about the problem before the 25k service.  "We'll look into it", they said.  On picking up the vehicle they did not mention the matter, so I asked about it. "Oh yes, that!", they said, "nothing showed up".  I don't know what that means and merely concluded that like most Ford dealers they simply don't know what they're doing!

BUT ... can any of you help me?  The problem is v periodic but every time it happens it sounds so bad I cannot believe that something somewhere isn't being damaged!

[Linds]

Clearly I'm on my own on this one ... but having thought long and hard I believe I now know what is happening.

Mind you, if anyone can steer me towards a similar post, I'd still be grateful.

[andypsp]

have you checked or had checked your brake pads and discs 

[suddste]

I have same car and similar mileage, I don't get that at all if that helps? 

[YOG]

12 hours ago, Linds said:

Clearly I'm on my own on this one ... but having thought long and hard I believe I now know what is happening.

So, what do you think is happening?

[Linds]

29 minutes ago, YOG said:

So, what do you think is happening?

Well having thought long and hard I realised I'd never solve the problem on my own (!!) so I went to see a really good mechanic who used to look after my Audi!  Having listened to the symptoms he asked, "Have you got Active City Stop?"  When I said, yes, he said it'll be something to do with that ... should be fairly straightforward for Ford to trace the problem.  Car goes in for service shortly (with a different dealer) so I'll see how I get on. 

[Linds]

46 minutes ago, suddste said:

I have same car and similar mileage, I don't get that at all if that helps? 

While it doesn't help at all, I am so glad you don't have the same problem ... indeed it seems no-one else has this problem.  Many thanks for the reply.

[Linds]

1 hour ago, andypsp said:

have you checked or had checked your brake pads and discs 

I haven't (hopeless with cars/mechanical things) but I will ask the dealer to check these.  Thanks for the reply.

[madmole]

I was about to say active stop after I read your description, so it seems you are following that path, check the radar sensor in the front grill is mounted correctly still

Other things that cause a noise like that is a stone or grit in the brakes (off roading in my land rover  its a common issue), but it doesn't seem that you are applying brakes at the time it happens (manually) so assume the car is panic breaking for you badly (try bleeding brakes) 

[Linds]

3 minutes ago, madmole said:

I was about to say active stop after I read your description, so it seems you are following that path, check the radar sensor in the front grill is mounted correctly still

Other things that cause a noise like that is a stone or grit in the brakes (off roading in my land rover  its a common issue), but it doesn't seem that you are applying brakes at the time it happens (manually) so assume the car is panic breaking for you badly (try bleeding brakes) 

Many thanks for the advice.  When I get the car back after its service I will post a review of the position.