Quote:
Originally Posted by T5R92011
The hose pipe highlighted is is a vaccum line that runs from the mechanical vaccum pump, to a plastic T-piece that then feeds both the front and rear vaccum engine mounts. The vaccum alters the stiffness of the engine mounts at idle to decrease the vibrations from the engine into the cabin.
When the engine mounts wear, they will no-longer hold a vaccum and you will know this because you hear a loud continous popping noise if you remove the oil filler cap with the engine running.
By putting a screw in the end of the pipe, you are restoring vaccum to the system and the noise will disappear.
On the older Euro 3 D5 engines (163 with no DPF), the vaccum system also operated the vanes on the turbo, meaning a vaccum leak would reduce performance, however on the Euro 4 D5s (Yours), the turbo vanes are actuated electronically, so putting the screw in doesn't affect turbo performance on those.
Essentially, the front or rear engine mount will be worn.
Look on Youtube for SiRobb's videos on D5 engine mounts if you want to sort it.
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Ah, interesting. So if I remove the bolt/screw will I notice more movement? Where would that end of the hose attach to normally? Or would it usually be open?
I hadn't budgeted for mounts. I'll try to have a closer look next weekend. Appreciate I should be looking for worn/cracked rubber, but wouldn't I notice excessive vibration in the cabin if they were shot?
I'd come across SiRobb previously, great channel.
Excellent insight. Thanks for taking the time.