Why exhaust camshafts wear out?

[ChrisS2]

The exhaust cams are more or less always in contact with oil (in the bottom of the cylinder head) dead mafs, sensors and longlife servicing is bad, period.
The only other thought is that the back exhaust cam is right next to the exhaust manifold collector, if that has any thing to do with it.
It could just well be down to how the cams are hardened in the first place, my car has done 220k, serviced every 10k at audi and spend nearly all its life on the motorway, my cams are fine. Maybe the stop/starting journeys on bad oil is an indication or poor maintenance scedual of Audi!

[BAX123]

Just got my B5 back from Audi last week. (i know i shouldnt have taken it to them, and i wont again, long story) but out of convinience over xmas it went to them and not someone like MRC. the problem was a ticking noise form under the cam cover on the near side of the engine, which i assumed was a hydraulic tappet problem or cam follower issue. turns out the cam chain tensioner needed replacing, and further probing revealed that the cam followers and cam on the exhaust side were worn and needed replacing.

My car has done 68k, and been on the long service schedule. i've only owned the car for a few months, and when i bought it there were no symptoms of it and the engine was tip top, just unlucky on my part i guess, and probably an indication that the service schedule every 20k isnt the best way to go. needless to say that i'm going to aim to have the car serviced by MRC twice a year and get a thorough and hopefully preventative service plan going.

Mike

[Contigo]

So are people happy to post their experiences? Maybe a poll as suggested, Has anyone suffered cam wear? What engine code, longlife service? Type of driving (short journey etc..) Audi serviced? Oil type used? Maybe help us to get a feeling for the sort of reasons why these things go.

[GregorFuk]

Might also be worth adding the cost of repair to that list of questions.

[wozza]

Had a word with a v.senior marine diesel engineer on the subject the other night - as engine failure is something they are very passionate at avoiding and want to know why it occurs.

Essentially cam lobe wear occurs due to incorrect tappet adjustment - too large a gap. This means that the wedge of oil that the cam lobe actually pushes on due to hydraulic action isn't there it also means that the gradual raising of the tappet doesn't happen and the lobe "smacks" the tappet taking off the very thin layer of hardening - also dishing the tappet surface.

As these are hydraulic tappets he quickly went onto concur that 'crap oil' (either wrong type or too old) is generally to blame and gumms up the tappet oil holes. Apparently fords used to be notorious for this problem using their 'recommended oil'.

Probably teaching you lot to suck eggs but I learnt something there so I thought I'd share.

Still peculiar why its the end lobes but hey ho - new cams and tappets are all the rage these days (just not for me yet)

[R5YUG]

To give you an idea of cost of parts to repair one side…

Exhaust Cams £166.33+VAT
Intake Cams £132.32+VAT
Tensioner £279.04+VAT (How much?????? WFT)
Chain £36.99+VAT
X6 Followers £112.32+VAT

Some interesting comments here… All sound very feasible – I’m inclined to suggest a combination of dodgy oil service schedule and manufacturing / hardening fault of the cams is to blame but in my case I know I had slight camshaft allignment issues which could have been caused by the tensioner failing or a dodgy fitting when last cambelt serviced by Audi.

I’ve only had my RS4 since September last year so can’t really comment on the driving style or service regime used by the previous owner. I regularly drop the oil every 6 months and use Synta Gold if anything it’s doing lots of short drives over long ‘very warm oil’ ones.

It was still on original MAF and DV’s when I bought it so maybe these should be considered as serviceable every 20k / 5 years? Equally the original fuel filter was changed during the cam service.
I’d be the first to admit I do drive it hard though, it’s been MRC custom mapped (1st owner had a Superchip which was pants and could be to blame as it was retarding badly), gutted downpipes and Cats with Miltek non-resonated rear.

I know earlier in the year when I changed the cam cover seal I didn’t have worn cams or damaged tensioner – and this was after a long drive to Worthersee and a hard session on the ring!

Either way my suggestion is to remove the cam covers at every service opportunity to check for wear / damage – Despite the recent big bills, I’m thoroughly enjoying the ownership and don’t plan on selling / changing in a hurry… Then again I’ve seen some very tempting and CHEAP (like a budgie) GT2’s for offer which is probably the only thing that can tempt me a the moment.

[rhunter203]

My car has been serviced every 10k (by Audi) has 70k on the clock plus has been fed Synta throughout its life and still suffered from the cams wearing on 'BOTH' sides!

The DVs were original (at 60k) and MAF was only replaced after 50k therefore may point to this. Doug did say that CAM wear was due to a design fault, therefore who knows!!

Cost me 3 1/2k for MRC replace 'ALL' cams, tensioners, chains and lifters so as you can imagine I'm not best pleased!!! Although saying that the car drives beautifully now – cheers Chris and Doug you are the nuts when it comes to repairing these expensive cars!!

[Virdee Autos]

This is all scary!

Checked mine around 5k ago, and they were fine. Now on around 85k IIRC.

Guy shocked to hear that at one point when you checked them they were fine, and then the next they were fooked! Thats the scary part for me!

Mine was on original DV's, MAF, and fuel filter like yours.

[andream88]

I've been @Colombo&Bariani ( http://www.colombo-bariani.com/index.php?lang=eng ) on Thursday with all my (damaged) cams.
They're quoting me the manufacturing of 4 custom cams with std diagrams.
These custom cams are CNC machined from 100% steel bars, and the chain gear is machined together with the cams (it's a one-piece product).
The cams are then surface treated.

Will post here on Tuesday with further details.
The more sets i order, the less we pay.

Andrea