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Focus MK2.5 Horrible noise when accelerating


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I recently bought a Focus MK2.5 2008 Duratec HE 1.8 petrol and so far I'm loving it... well apart from an annoying noise I've been getting when I accelerate suddenly (Quickly) in 2nd or 3rd gear. It doesn't do it every time and never seems to do it until the engine has warmed up. It also only lasts maybe 2-5 seconds.

I've recently changed my PCV valve, which was a pretty stressful day, but I can't think of this being the reason (Unless someone has any ideas). I was thinking of a kink in the PCV Valve hose but I'm not getting any telltale signs. 

I had the car checked by a garage (externally), but they couldn't spot any issues and of course they cannot replicate the issue.  😞 


I found a video of someone having the same issue albeit a lot worse then mine. I've cropped the video and included it in the thread. They're running a MK2 Focus 2.0 2006 petrol engine.

I've tried unplugging the swirl flaps airline, but it doesn't stop it so I guess that rules them out. 


Does anyone have any ideas, it's driving me nuts. I'm driving over 300 miles next month to wales so I'm getting worried! 

Please any help would be great!


Thanks 🙂


Edited by Davek1995
Fixed video link
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5 minutes ago, stef123 said:

Just diagnosed a similar problem on a 1.6 focus making a similar noise on hard acceleration. 

One of the brackets on the exhaust just after the flexi had snapped. 

Thanks for the quick reply! is that area easy to get to? I've got the black pain under the engine covering most stuff up or is it further back?

I did wiggle the exhaust forwards and backwards and couldn't hear anything last week, but I might pop out side in a minute to go check!

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18 hours ago, stef123 said:

I spotted it after a very brief test drive. From the passenger side I looked under from just behind the wheel. I could see the welded portion of the bracket had snapped. 

I can see this which is in the centre of the car, seems to be fine 😞


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8 hours ago, JONATHAN_11_80 said:

Ive got a 1.8 duratec thats an odd noise it seems to kick in underload.  I am thinking you have a failed drivers side engine mount.  When mine failed the car made many strange and alarming noises.

I'm not sure cause it doesn't make any noises when revving, which I'm assuming would happen. 

8 hours ago, stef123 said:

Have you had a general look round the suspension and anything else that may move or twist under load? 

 I've wiggled everything I can think of and so has the garage. 

I did take her for a run last night and put down the passenger window. I could hear a puffing/ hissing kind of noise almost like a steam train, which starts around 20 mph not sure if they're related. 

I'm thinking I'm gonna have to take the manifold off again to double check everything 😞

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** Update ** Just took it to the garage and drove it with them. 

They suggest checking the spark plug gaps and try using some premium fuel. I did change the sparks about 3 months ago so I suppose it could be, but it seems a little off to me.



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On 9/26/2018 at 6:03 PM, stef123 said:

The first time I watched the video I thought to myself I hope that's not the sound of the big end bearings.

I don't think so. I went to Tescos and bought their 99 octane stuff and within 10 minutes the noise had stopped! He checked the spark plugs today and the gap was well out.. 

Hopefully I can go back to using normal petrol soon.

Just happy it's all working! Thanks for all your help 🙂

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