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View Full Version : 2000 Bora TDI PD - uneven idle



Boraman
27-04-2007, 11:34 PM
I noticed this a while ago - when cold-started, engine intermittently jumps in idle, as if pistons/combustion sequence loses sync every now or then. This is accompanied by a strange noise - just like some air trapped somewhere inside is released suddenly. After this, let's say mild thud, it all goes back to normal (until the next loss of sync and *thud*). This has absolutely no effect on car's performance - she still pulls like crazy, cranks without a second thought, fuel consumption is normal - all in all, works normally; it's just that I wouldn't want this to slip by my nose and turn into a major failure.

Any ideas, anyone? I'd rule out camshaft being worn right away - I had head gasket replaced recently and I suppose they (local vw garage) would have warned me about this then. And I've searched on this here and in other forums, but to no avail.
BTW (if this makes any sense here): I noticed traces of oil around EGR 'mushroom' (actuator valve?).
Any info would be highly appreciated. :beerchug:

shooey88
27-04-2007, 11:46 PM
the mushroom people are calling...is a vaccum pump solenoid that actuates the EGR flap. having a slight oil leak from the EGR is everywhere on this website. to solve it you replace the EGR unit at a nice price of about 200 pound plus. but really whats with the big fuss about it....wipe the oil clean n forget about it. unless its a major leak i cant see why everyone is getting upset by it?

shooey88
27-04-2007, 11:49 PM
o and to ur original problem....why did you have the headgasket replaced? did u have a major oil leak? did your car overheat and headgasket blow? has your problem happened since you had the repair work?

Boraman
28-04-2007, 11:05 PM
Umm, yes - overheating and loss of coolant after high speed motorway drive and/or going uphill. Here'w what actually happened (and this seems to be a common fault on early PD's): head gasket developed a hairline fracture aka microchannel between combustion chamber and cooling channels in enigne head/block. WHile driving under high load (just as described above), a part of exhaust gas gets pushed through this fracture into cooling system causing pressure build-up and consequent ejection of coolant via overpressure valve (pink dried coolant marks all over the engine bay). So, after a while I'd get a horrendous 'beeeep' and "Kühlmittel prüfen" message on display. A 150€ later, problem was solved and this has never happened since.
So, if the coolant boils when you undo the blue cap on the expansion reservoir and stinks like exhaust, you've got a faulty head gasket.

As for EGR and oil around it, I'm trying to figure out whether the damn thing needs cleaning (in attempt to fix the juddering problem). Another less expensive thing pops into my mind, namely idle fuel injection quantity adjustment. All after that (new injector/-s or something even more expensive) simply freaks me out...

shooey88
29-04-2007, 07:14 PM
as u described...maybe ur problems is consequential engine damage when your head gasket went and car overheated....not a good sign. engine strip...o hope not for u

shooey88
29-04-2007, 07:16 PM
hope its sumthing simple and not expensive

Boraman
29-04-2007, 09:57 PM
I'd say it's caused by soot build-up all over exhaust and EGR circle mainly due to city drive. Today I drove her rather harshly up hill, and the idle stabilized - purrs (or rather hammers...it's a PD :D) like a kitten again.