Porsche Enthusiasts Club Forum

I am not sure that Tiptronics suffer more than manuals, I thought it was the other way round.

How much damage is caused by overrun on an engine full of 12 months plus old oil

Surveys & engineering reports in the US show that A. Garage queens fail more than high miles cars. B. Tips more than Manuals. C. Cars driven hard suffer less than cars driven gently. D. Tracked cars fail very rarely. E. Long maintenance intervals maybe part of the issue.

Some of the above maybe linked, e.g. less Tips do track days than manuals etc.

The bearing is overloaded, especially in early engines (bearing got updated the later it is). The bearing is shielded & full of grease (when new). As it ages the grease gets washed out, the light oils used by Porsche aren't adequate to lubricate the bearing, especially given it is overloaded. Also the shields whilst not keeping the oil out & stopping the grease getting washed out don't allow adequate flow of oil to wash the detritus out, so fragments remain. Overloaded balls (ooerr) start skidding rather than rolling & then spall. Failure of the bearing is not far behind & then the IMS shaft moves stopping the cams turning. Also the muck from the bearing gets transferred into the oil & around the engine causing massive collateral damage.

Also linked to oil is bore scoring, lugging the engine at low revs from cold & switching straight off after a fast run are believed to exacerbate this. Later engines run a piston friction coating which flakes off & damages the bores as well.

Thanks for the advice Jim, I will take a look and make some phone calls.

I'd love to know what you find out Jim - speaking as one with scored bores / wrecked engine

Waz

Meant for Cleggy but either will do lol

Oh and ...... is a failed IMS something we can insure against I wonder? (probably not)

Nope! Unless you have a Hartech/Autofarm type rebuild which starts at £4,700 or so & who'll do that on a 5K Boxster, Cayman or 911 for that matter?

More frequent oil changes, possibly of a higher viscosity, more ZDDP which probably means not Mobil1.
I've only had one oil change since I've had the car (<2K) & I provided a 10W/40 SL B3 spec oil to the OPC for it. I intend giving it another oil change myself shortly once the siberian winter finishes. DIY & a 944 with dead ABS have intervened today.

Can anyone confirm then that if you need an engine rebuild replacing the IMS (or fitting an uprated one) is a better all round option than fitting a well sourced, used engine given that the risk of IMS failure would be lessened? W.

IMS failure doesn't disappear as an issue until 2008 when it was designed out. So a s/h engine gives you the same unknowns.
There are various options, listed in increasing cost options:-

Rebuild your lump with the latest Porsche parts.
Rebuild your lump with an updated IMS bearing such as LN or Autofarm etc.
Exchange your engine with a Hartech etc. rebuild.
Exchange your engine with a OPC etc. rebuild.

Thanks Jim - looks like I'm going for the 2nd option!

We have two Boxsters in at the moment for IMS bearing retrofits. One is an early dual row, had not failed completely, but had become noisey, and another which is a later single row bearing which had failed and the jury is out on if it has caused damage to the engine.

If my Boxster, Cayman, 996 or 997 needed a clutch, I would certainly have the IMS done at the same time. But it is understandable why some people with an early Boxster choose to not have it replaced during a clutch change, the values of Boxsters have taken a tumble in recent years, but.. even the earliest Boxsters tend to be worth £5k and above, but one with a failed engine is worth next to nothing, unless it has clear indicators fitted all round, in which case it is worth £400 more

All Porsche cars have an Achilles heel, the 944 8v have number 2 bearing issues, the 16v 944 has cam teeth sheering, the 968 the same, the 911 (especially the SC) have issues with head studs, the 964 prone to oil leaks, the 993 having issues with hydraulic lifters.. But anyone who has owned these know that the problems are very much in the minority, but still worth taking steps to avoid with good maintenance.

Interestingly, we see more 996 3.6 engines with failed IMS bearings than any other car with this engine, that includes all boxsters, cayman, 996 or 997 models... I would guess we see 5 996 3.6 needing an IMS for every 1 we fit to any of the other models.

But most of the ones we see with failed IMS bearings tends to have a less than perfect service history, with oil changes stretched beyond yearly, or have had oil changes without oil filters.

We even see some Boxsters and 996 with full service books, but unfortunately a long line of Porsche factory specification low mileage services, which do not include an oil change... one we worked on had a full service book, with yearly visits to the main dealer, but for 10 years it had seen only low mileage services and the owner had no idea that these £150 services did not include any filters or fluids being changed!!

I had a headmaster when I was at infants school who had a moto of "Accidents do not happen, they are caused" I think this sums up Porsche engines, if looked after they just do not wear out, if some expert eyes see them once a year and their advice followed, Porsche engines do not suffer "accidents."