cpayne

I did a couple of searches and didn't come up with anything. Is there such a guide that lists the average MTB Mean Time Between failure data for our cars?
Example:
Bills car has over 200,000 on it. He just decided to R/R the TT, TC, but it was still in good order at least the TT. Others have not had such luck. I think averages must be available for a car built with such engineering and from the ground up.

I have many years of receipts from PO's some major repairs and I was considering the WYAIT approach given the 159,000 miles on it.
While we all know about TB/WPs, what about some of the other major components of the car that are pricey to repair. Clutch, Intake, head gasket, etc...
Has anyone seen this in the WSM manual maybe a table somewhere.

Thanks

Charles

SteveG

This might be an intersesting number in industrial applications, but in 10 years lurking here, I've never seen it discussed. We don't get much beyond the timing belt parameters of 60K miles or 5 years and that is sometimes ignored. The many other wear items like cam gears, oil and crank gears seem to have a mind of their own. Was it you who just brought up the "premature TB" demise? Some, like the alu ball joint (recalled) were bad design and some deteriorate due to bad maintenance, like a too tight Tbelt on the cams causing premature wear. I replaced cam gears on a GTS that had (only?) 69K and was maintained by Beverly Hills Porsche prior to my purchase. Some say that is normal and others have cam gears that go a lot longer before replacing. "YMMV" is pretty much the rule.

danglerb

Much of the failures have more to do with previous owners than Porsche engineering.

Landseer

Nothing is available to correlate it all and spit out a formula. Far too many usage variables for automobiles. Its not like predictive maintenance on rotating equipment or electronics lagged into closets in racks.

But the renaissance tool is right here, before your eyes.

By parsing through posts on internet sites a systematic thinker can pretty assimilate the data from many owners. Combine it with some real world experience fixing them and patterns emerge strongly. Its amazing.

When it becomes a PhD engineering project, I'm out.

Its interesting to me so long as its an art.

If you get good at fixing them, it doesn't matter much.
I'm putting one together that should get TT bearings replaced because they are starting to go.
But I'm out of time and money for now.
So, I'll spend a day and a half sometime next year doing the job again.
Its therapy. I don't need predictive models to tell me to replace the wear parts.

cpayne

No that wasn't me even though i currently have the cam gear wear and TB problems.

Hilton

Too many variables to get meaningful data.

Driving style will hugely affect the lifetime of a clutch, gearbox and engine. My '89 had the original clutch in it at 150k miles, whereas my white '87 had its clutch replaced at 110k.

The type of oil/coolant used, regularity of fluid/filter changes, checking/replacement of wear items (cam gears, oil pump gear, seals) all have a huge impact on failure rate.

With the right service history and fluids, and if compression still holds, then there's no reason to consider a rebuild.

There's a documented rebuild at 213k miles (340k km's) of a local GT with a known history (factory trained 928 mechanic who's also a ZDDP-minded oil buyer). The mechanicals measured within the "new" tolerances per Porsche's technical documentation. The rebuild was because the motor was leaking from various (original) rubber seals, and it was easier to just pull the engine to re-seal it.

If you're trying to work out what needs doing, your best bet is to get an experienced eye on the car. It likely needs:

• new rubber fuel lines
• clean all ground points and fuse/relay connectors
• timing belt job including all belt gears, tensioner rebuild, rollers etc.
• engine mounts (and likely oil pan gasket)
• intake refresh (knock sensors, throttle switch, vacuum lines, gaskets, and maybe a few other sensors depending on condition)
• valve cover re-seal (plug seals, valve cover, cam chain tensioner pad, oil galley plugs etc.)
• HVAC and Cruise Control vacuum system diagnosis and repair

On getting a "new" 928, I start with replacing all fluids/filters, and check out the basics like brake rotors/pads and e-brake shoes/adjustment, clutch (including pedal adjustment), tires.

Then I do the above list - even if the car's had a recent timing belt job, experience tells me I need to go in there and check tension and replace whatever they failed to do properly (like rebuild tensioner).

Landseer

Brakes, CV repack, steering boots, tie rod ends....

Pretty much par for the course on non-scrupulously maintained cars. In fact, so predictable you can pre-buy the stuff, put it in a box, and be ready when you drag the next one home. What you don't use, goes on the next one.

ROG100

All parts should be replaced every 3000 mile oil change interval.
But I guess I am biased 8>).

Mrmerlin

FWIW if you go through the FAQ you may be able to gather some info about what most of the failure points are,
then you can have a baseline of what most of the expected repairs will be and when

NoVector

The attached schedule from an old DEVEK catalog is probably the most complete I've ever seen. / Bruce

Ethre

I think that any attempt to analyze people's experiences to determine a Mean Time between Failure would result in highly erratic numbers. For direct failures it might work, but for other wear/tear I think you might find a whole range of ideas regarding when it was "necessary" to repair/replace something.

Just my two cents.

cpayne

Not a bad guide thanks

cpayne

I'll take 3 of everything then. I'm waiting for my bail out check to get here any day now. If you can spot me i would appreciate it.