Problems with Boxster 3.4S engine?

[nickw00d]

hi all ... I'm new at this, so go easy on me please.
I'm looking to buy a 2007 (ish) Boxster & had my heart set on a 3.4S. I've driven several & it ticks all the boxes!
I've just been told that the 2.7 is a much better option as the 3.4 can have problems with con-rod shells? Is there any truth in this? Also, is there much noticeable difference in performance? Thanks.

[tr7v8]

OK there are various problems with the M96 engine as is used in this era of Boxsters, Caymans & 911s
Very early 2.5 engines suffered other various issues, but the general issues are:

RMS, Rear Main Seals these weep & very rarely cause a major issue. When the gearbox is dropped for a clutch change then the seal can be changed.

Bore scoring: this is where the plated alloy bores suffer scuffing & suffer excessive oil consumption. Normally bores 4, 5 & 6 which is the hotter side.
Various ways of reducing this risk. A. Drive it harder, cars that are tracked & raced don't tend to suffer this. B. run a heavier oil than Porsche spec 5W/30 Hartech recommend 10W/60 & I run 5w/50 Comma Motorsport which is also a lower API spec than the current oils used. C. Don't let the engine lug in low revs/low gears. Tiptronics are bad for this as they pull away in 2nd gear unless in manual mode.

IMS (Intermediate Shaft) Bearing: Crap design by Porsche, the flywheel end of the intermediate shaft is supported on a skinny bolt & by a bearing which is shielded. It starts off grease filled & after a while debris gets trapped behind the shields & eventually the bearing collapses. Or the bolt breaks. The bearing can be replaced whilst the RMS is being done, although some do not recommend this, others recommend a complete strip down to replace. If the bearing lets go then the damage can be immense. At the very least all the meal debris goes through the engine & needs clearing out. Running the heavier oil as detailed above helps.

Bore distortion: This is at its worst the bigger the engine. At high miles the unsupported cylinders distort & again massive oil consumption is the outcome.

[nickw00d]

Thanks Jim ... much appreciated!

[JasonGibson]

Whereabouts do you live ?

[WazzerM]

There's a thread or two on here somewhere about my Cayman engine saga (M96) that might be worth a read. Before purchase check the contents of the oil filter - for debris (as Jim says). If clear / clean you at least you know IMSs's doom is not imminent. It is rare though remember. Also, check the coolant - it should be clear, if it's muddy brown run away! Great cars though, oh yeah - just need to be careful on choice. I bought a 2.7 too and love it - and tis less risky all round. Good luck.