Hi Rob,
I was in a similar position to yourself when I saw the price of the early Cayenne's and dug a bit deeper like you are doing now.
i ended up quickly seeing that the V6 (and VW) engines are too small to power the 2.5 ton beast... and that's without the additional water weight in the drains! The V6 is very reliable though... just frustrating to be using so much throttle and still end up not really getting good performance.
The 4.5 V8 in the Cayenne S seems to have had some blocks suffer from cylinder bore wear (due to the type of coating used degrading, may be due to modern fuels used and their reaction with the liner coating). Regardless of cause, it wasn't something I wanted to be getting into as you'd be arriving with compression tester in-hand etc.
I therefore did not see the point in a 4.5 'S' when I read that the turbo uses a different cylinder coating and does not appear to suffer with the bore wear issue. Turbo gives approx less than 1mpg difference in fuel economy yet with the twin turbo pushing output to 450HP!
Add to that the fact that turbo's end up having the extra spec that you normally try to hunt out such as electric heated seats/steering wheel with memory position, Bose, air suspension, auto dimming mirror, extended leather .... and so on.. meant that I was sold on the idea of a turbo.
I found one for under 10k that had sub 85k miles and never regretted it. Same issues are to be checked for the coolant pipes as mentioned by others as that applies to all the V8's including turbo S too.
I've changed the belt on service after I bought mine and it is a bit of a long job because there's just not much room in there with that engine! Still completely doable job if you're competent so goes to show you don't need to pay specialist/dealer rates to change what is effectively a standard auxiliary belt that would be the same in any engine.
Oil changes services/filters also easy, changed mine fine every 5K because I'd rather have good oil in there for relatively little outlay. Air filters again a bit awkward due to space but not too bad at all considering.
As also mentioned above, the drains are absolutely critical to check on these and can cause electrical issues of course, if not kept on top of. Shame it's not a standard Porsche dealer checklist item.
Tailgate struts are quite hidden away so now the weather is getting colder they will be weaker... they are around £100 - £150 for the 2 x main struts if you shop around for a deal. Those 2 big struts are what do most of the work as the smaller struts are really for the rear window when opened on its own. Often you find the smaller struts are fine and do. It need replacing as the window is not often used on its own. You can of course replace them all at the same time as they are all housed beside each other and the labour is similar. I have replaced mine as they needed doing from purchase.. I just accounted for the work which just takes a bit of patience.
There's a top engine torque arm (you can see it when viewing engine bay on left hand side) that may also have had the bushings perish at these millages and with the heat. This is a simple one to replace as its so easy to access. Less than £100 for the part depending on which you go for.
Check that the rear window washer works well with fluid coming out as I have heard there can be issues with the tubing splitting at a join which is just above the right hand side A pillar. This would be another problem for electrics.
Last but not least they all seem to need frequent cardan shaft bearing or bushing replacements. First the rubber bushing goes that supports the bearing which the drive shaft to the rear runs through. If left too long the bearing itself can also fail. There's a lot on the internet about this so take a look. You can check it more easily with air suspension or if you can get under the vehicle, where firmly trying to press the shaft towards the underside of the chassis would reveal the condition.
There are good quality redesigns of the cardan shaft support out from EPS if you search for those online, which put my mind at ease. They basically allow you to not have to remove the whole shaft as they are installed in two halves with the cardan shaft already in situ, one on the chassis side first, then the remaining half on the ground side and bolts back up to the original threads.
Mine checked out fine when I inspected at purchase and has been fine since but at least the EPS solution is good to know just in case. Also specialists deal in this cardan shaft support/bearing issue and can supply and fit the reconditioned part given they are all shared across the Cayenne/Touareg/Q7. To me it seems the mount is clearly unable to cope with the weight/force on these vehicles and I don't believe a redesigned part was released... which is why I would be replacing with the EPS solution rather than bolt on the same spec part again which will clearly fail again in the not too distant future!
Window regulators can also fail which is same likelihood as other cars I would guess however the complexity in replacing is vastly different! I replaced mine with a new one and the amount of labour was staggering even with a lot of prior reasearch on how to do it. Let's just say the doors are over engineered and don't have the usual 2 skin arrangement!
Well that's my thoughts on these beasts. I'm considering selling my turbo (now on 95k miles) but honestly think I would end up replacing it with another younger model turbo!
I didn't really see the point in thesee cars before but I needed something really comfortable and capable for doing longer journeys to race circuits and this thing converted me big time!
Contact me with anything else you think of as I'm sure there's stuff I missed out.
A durametric obviously helps too but that goes for all Porsche!
J
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