Hi everybod,

Can anyone give me some advice.....I've noticed that appx 5 seconds after I switch the engine off on my 03 Octavia (1.9 TDi Ambiente) there is a soft thud from the engine area (as if a damper flap had closed). I rang my local Skoda dealer and they couldn't immediately think of anything. Any ideas? No other problems with car apart from this.

Thanks

IIRC there is an anti-judder valve somewhere near/in the EGR assembly that should stop this kinda thing. Now I'm not 100% on how this works but it sounds like it's got clogged up a bit and/or has failed somehow.

What you say about the anti judder seems plauseable or a cut off solenoid that is being odd.

I had the failed cut off solenoid on an old XUD engined car.

IIRC there is an anti-judder valve somewhere near/in the EGR assembly that should stop this kinda thing. Now I'm not 100% on how this works

That fits in with something I found in the Haynes manual the other day. When you turn off the ignition, it stops injecting fuel, so the engine will stop. Because diesels have a high compression ratio, though, the engine can judder as it comes to a halt at it fights to compress the air in the cylinders.

So, there's apparently a flap/valve that blocks off the air coming into the engine when you turn off the ignition. This means there's very little air to compress, and so a smoother stop. I think the flap is vacuum powered, and controlled by a solenoid (like the EGR valve), and there's a spherical reservoir of vacuum under the engine cover so it can still work as the engine stops.

but it sounds like it's got clogged up a bit and/or has failed somehow.

Maybe, or maybe it's just doing what it should. I've got a feeling that Haynes reckoned that the valve shuts for a while (to make sure the engine stopped smoothly), and then opens again (ready for next time you start it). You might just be hearing it open again.

I've always noticed some sort of a click/thud on mine a few seconds after stopping the engine, but I just kind of filter it out now. I'd always assumed it was just a relay until I read that bit in Haynes. I'll have to listen out for it again & see if that's what it is.