exhaust and or gearbox mount problem

[joekellner]

Hi everyone. I have an 03 plate 406 hdi 90. I sent it in to the garage today along with a new gearbox mount as the car is very juddery on pull away and when you switch off you can hear a metal knocking and feel the car shake leading me to believe a worn mount. The garage called me shortly after telling me theres nothing wrong with the current one and test drive seemed fine as did the clutch. He told me its my back box that is nackerd. Which I know this already and he said the cars lumpy because its losing back pressure? ? Im baffled. I really cant imagine the back box causing this issue. When I bought this car 2 months ago it drove like a dream and now throws us back and forth if we pull away like normal. Anyone have any advice? Ill get the exhaust done anyway but can a mount be worn with out looking worn?? Thanks everyone.

[OllieNZ]

Have you checked the bottom engine mount?

[joekellner]

Hi thanks for your reply. Yes this is the mount in question. He seems to think its fine? I just cant believe a simple back box would make it seem like theres a mount shot to bits?

[gumby6371]

A simple test for a worn bottom mount is to rev the engine and see how much movement there is, It shouldn't move more than about an inch.
excessive judder on start up or shut down is also a sign of a fubar'd mount but I don't recall mine juddering particularly while pulling away.

You might try telling the fitter to put a new back box on and you'll pay him 'IF' it fixes the problem

[joekellner]

Ok thanks. Im convinced its nothing to do with it because im 95% sure it was jufdery before the back box gave way.

[rwb]

I asked my regular mechanic about the bottom mount on my HDi 90 and he said it was fine.

When jasper5 came to change the clutch a couple of months later he found it was in fact knackered.

A new bottom mount make it pull smoothly from 1200rpm like it did when I got it (3 years old).

[Welly]

A Turbo-charged engine is not affected by eggsauce back-pressure (or lack of) it's a totally different principle. NA engines need back pressure for eggsauce gas scavenging to help engine efficiency but turbo's simply don't need it [T-shirt, Honda, expense, etc]

Once the eggsauce gas has passed the turbine its done its job and could end 6" thereafter. A blocked silencer is another story though, sometimes the back box can snap off but block the incoming pipe.

Check that lower engine mount! the engine should not move much at all if correct.