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Robert, UK Qualified Car Technician
Category: Car
Satisfied Customers: 4708
Experience:  Fully qualified / self employed garage technician in the UK
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Just had new head gasket fitted and new swirl flaps. Car now

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Just had new head gasket fitted and new swirl flaps. Car now running rough/juddery as though not firing on all cylinders. Worse on cold start but improving a bit when engine warms. Garage claims it's now the drive shafts at fault. Didnt have this issue prior to the work being done. Are they taking the micky? ?
Why initially was a new headgasket & swirl flaps fitted?
Any engine lights on since this fault occurred?
Registration of the car?
Customer: replied 2 years ago.
I had an overheating problem where the coolant would disappear only to refill the tank when you released the cap. There was also a lot of back pressure. No lights on since the repair but I am now getting black smoke on acceleration as well as rough running.
Car reg EA06WFT
Ok..for starters there's no way in all my years in the trade.have i heard of driveshafts causing running rough/juddery engine performance,black smoke - driveshafts only transfer power to the wheels from the gearbox thats it..and the garage shouldnt of been near them to replace a headgasket or swirl flaps on that engine,because its quite a common diesel engine and can be found in other makes including vauxhall,fiat's etc,so the swirl flap issue can be common but normally its down to the actutor,control rod breaking the opens and shuts them,aftermarket kits to solve that....
By the way of your description of say as for starters check every intake hose,intercooler/vacuum line is connected and for leaks and are they would off been removed during the job..also check that all harness plugs are fully connected.especially around the injectors also maf is plugged in - next will be more involved id say check timing again.the injection pump inst timed so its really cam timing id say needs checked.they should off used a new timing belt kit after the head had been torqued down..if they've used the old belt then thats bad practice - egr valve needs checked out - It may also be advised to actually do or get a compression test done on the engine..although it means having to get the glowplugs out carefully..doing a compression test will rule out any low compression resulting in the missfiring or black smoke..if low compression is found to be the cause..then steps need to be taken to find out why ie: if it been due to an installation error when retiming the engine.valve to piston contact for checks would need to be done on the 4 injectors to ensure none of them has developed a fault or dribling causing excess fuel to enter the cylinder(s) a leak down test might show that up..But as above thats about the checks that would need to be taken into account..I do hope this helps
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Customer: replied 2 years ago.
The garage states that as the engine now has more torque it's showing up the fact that the drive shafts need replacing...hence the juddering on acceleration, but I can't see that would cause the black smoke. I think I need an independent report to take to them and will consider what to do next. Many thanks for your advice.
Its very rare for both driveshafts to show wear just like that after a headgasket change... Its not something ive ever heard to be honest in all my time as mechanic..driveshafts show wear over a period of time insitally by excess movement or clicking noise's emiting from the cv joints either inner or outer on full lock either direction depending on the extent of the wear...and if juddering is being experianced under accleration then beside a missfire issue on the engine - the obvious places to look at is your suspension on the front/ engine mounts / and lastly clutch - But in all honesty get a second opinion on this.and recheck of the work done..the black smoke cant be caused by worn driveshafts any good mechanic including myself would tell you that..the black smoke is attributed to something else on the engine at highlighted in my other answer..