HOW TO: CHANGE THE EGR VALVE ON A CAYENNE DIESEL

The second-generation Cayenne Diesel – and by implication the contemporary Panamera and perhaps in time even the Macan models – would seem to have a voracious and expensive appetite for exhaust-gas recirculation valves, certainly if the 2011 car shown her

Secondtime in two-years for this particular 2011 London based car

It is fair to say that far too many modern cars, for all of their positive attributes, are victims of their own sophistication – and of their makers’ quest for both environmental ‘friendliness’ (increasingly and some might say unrealistically forced upon them by power-hungry politicians) and ultra-compact packaging. Figuratively squeezing a quart of hard-workingmachinery into a pint pot. Perhaps a hefty dose of so-called built-in obsolescence, as well; you don’t want to build them so robustly that you eliminate any repeat business, do you?

There can be few better illustrations of the problems this brings the end-user – that’s us; we Porsche enthusiasts, and even those to whom they are merely ego-massaging luxury cars – than the second-generation Cayenne Diesel shown here. Brand-new in 2011, it would have cost its first owner around £45,000. He was doubtless persuaded to part with his money by its suave combination of style and fuel-efficient performance, by its solidity and consequent safety, and not least by the notion that he was buyingquality; somethingthat would last the distance.

And, in a way, it is lastingthe distance. Accordingto Britain’s Society of Motor Manufacturers and Traders, the average age of UK cars when scrapped is today just short of 14 years. At nearly half that figure this one, with its zinc-protected body shell, is in structural and cosmetic terms just as good as new. With care – demonstrated by the observable longevity of the many other

Combined EGR valve and heat dissipator (or heat-exchanger, perhaps) is mounted at the rear end of the engine, between the two banks of cylinders (facing page, top). That alone makes access rather challenging – find yourself a suitably safe stool or trestle to stand on – and then there is the small matter of the literally several dozen hoses, pipes and electrical connections that must be separated. We’ve shown the bulk of them in the group of photos on the right, with still more on the next spread, but do please note that this feature is intended primarily as an overview of what needs to be done, rather than as a definitive, workshopmanual-style guide. If you know what you are doing the work is just time-consuming rather than difficult – and remarkably few tools are needed. If you don’t know what you are doing, on the other hand, then you will be well advised to leave the task to a professional. At least you might now appreciate why the bill could appear to be so steep... In truth, it would be a lot quicker, easier and seemingly cheaper to replace the EGR valve alone (and it is available separately), but there remains the obvious risk that the heat dissipator is as gummed up inside as the valve itself, and you will end up doing the job again in the fairly near future. But then based on the experience of this car’s owner, maybe you will anyway...

German and specifically Vag/porsche vehicles on the roads today – it might be expected (ignoring now the obvious threat from hybrid and electric technology) to serve for well over 20. But at what cost in terms of peripheral but essential replacement parts, and not least the labour to fit them?

In 2014 my colleagues at Auto Umbau, Robin Mckenzie and Terry Parker, fitted a 2011 Cayenne Diesel with a new exhaust-gas recirculation (EGR) valve and its associated heat-exchanger. Their experience provided a timely and pertinent answer for what was then the Q&A section of the magazine; see the panel on the previous page. Total cost of the parts and labour was around £800 plus VAT, and while that might be argued to have been a modest proportion of the car’s then value, it was a sizeable figure for something that ought to have been at least as durable as, say, the engine itself. And you might expect that its entirely new, Porsche-branded replacement, perhaps re-engineered and improved since the car was first built, would have fixed the problem, once and for all.

Wrong. Or so it would seem. A few weeks ago Robin rang me to suggest that I might like to cover as a how-to story the Egr-valve job he was about to tackle on a 2011 Cayenne Diesel. Perhaps understandably, given the large number of Porsches that he and Terry work on, Robin had probably forgotten that I had covered something similar with him in 2014, but it became apparent that not only was this exactly the same procedure as back then – and I am always on the lookout for trends in component failure – but exactly the same vehicle. Clearly this warranted closer investigation. (The latest bill came to £1200. That was £654.09 for the combined EGR valve and heat-exchanger, and £546.00 for seven hours’ labour. All figures include VAT.)

That investigation is best described as ‘on-going’, and it will not be overly scientific. But I still have the car’s original, factory-fitted Egr-valve assembly, salvaged from Auto Umbau’s skip (partly because it seemed wasteful to throw away such a large and seemingly undamaged device), and I shall be doing my best to find out why it – and by inference its replacement – ceased functioning. One obvious suspect has to be the fact that the car spends much of its time running at low revs in central London, to a greater or lesser extent breathing in its own exhaust fumes. But then no manufacturer – and certainly not Porsche – warns of the likely results of that sort of usage when you pitch up to buy a vehicle of this nature.

Whether any diagnosis is achievable

If you choose to do this job yourself you will need only a few basic tools – but both the patience of a saint and perhaps the confidence of a time-served brain surgeon as you work your way through a veritable Chinese puzzle of hoses, wires, cables and pipes. And still there will be more to detach before you can even see the EGR valve and heat dissipator, never mind extract them.

One problem, as alluded to by Robin Mckenzie on the previous spread, is reaching in over the engine (the valve is high up in the valley between the two banks of cylinders), but Terry Parker, man on the spanners this time round, solved that by placing the car on a two-post lift and removing the wheels, such that it could then be very carefully lowered until the brake discs were almost touching the ground. Failing that, find yourself some suitably secure stool or trestle to stand on.

You will need to drain and save the coolant (mop up any spillages immediately, to avoid the possibility of poisoning inquisitive children and/or pets), and obviously later refill the system. Be warned, though, that even then quite a lot of liquid might drain out of the heat-exchanger element of the EGR valve, and end up in the aforementioned ‘valley’. Terry used a purpose-made fluid extractor powered by an air-line to suck it all out, but a good wet-and-dry vacuum cleaner should do the job, too. Again, correctly dispose of any fluid (this portion will probably be too contaminated to use again), and certainly don’t be tempted simply to leave it on the engine to evaporate later.

Most of the fixings you will encounter are of the Torx variety, but you will need a good armoury of extensions and drivers to get at some of them. Hoses are secured either by the now equally commonplace Oetiker clips, which can be undone with an angled pick, and usually leaving them suitable for use again, but even if you have the necessary special pliers to retighten them are best discarded in favour of good, old-fashioned worm-drive clips. If not, some are impossible to refit, while the traditional ‘Jubilee’ clip or its equivalent can be tightened with a screwdriver, able to reach in where pliers cannot, and will do just as good a job.

Be careful when disconnecting the many electrical plugs that you don’t break any of their securing tabs, and if necessary non- destructively mark them so that you can easily identify them (and any other pipes and cables, for that matter) for foolproof reassembly. Alternatively, use your phone to take close-up photos. (It is not really our intention that you should use those published here for that purpose; we have tried merely to give an overview of the work involved.)

Finally, when you have peeled away the many layers of hardware, and the EGR valve and its heat-exchanger are seemingly free to be lifted up and away, make sure that you have undone all the fixing screws – the new unit will give you a good idea of where they are located – and even then be prepared for a titanic struggle. There is barely a millimetre between each side of the aluminium casing and the oil filter and the turbo, and you will wonder if it will ever come out. But come out it will, just as the new one will (just about…) squeeze back in again.

That alone is one of the many reasons why you don’t want to do this job more than once, and certainly not more than once per car. But whether or not that proves to be the case surely only time – and perhaps the way you continue to drive it – will tell.