Top End Rebuild ?

[timlit]

Advice Please,

Car has done 107k miles, smokes quite a bit on start up from cold, no smoke on hard accleration or lift off.

Have just added 1 litre of oil after 800 miles, since having a 24k service.

But having just installed a chip, which only gave +10 bhp, the dyno reading only gave a reading of 175 bhp before chipping.

So am down 50 bhp on original, car feels a bit sluggish uo to 3 - 4 k rpm and them goes well.

Have got the money for rebuild, but do I need to ?

 

[chas3.2]

Do you have a 3.2 Carrera or a 911 SC what year???

 

[chris.hevey]

I suspect a simple compression test may reveal a great deal....

 

[vic cohen]

+1 compression test, next stop .................try coing on Impact bumpers site.................u ll be swamped with ideas

 

[timlit]

Hi Charles,

Put post in wrong slot. Car is 3.2 Carrera 1988

 

[dij999]

Do you have a 3.2 Carrera or a 911 SC what year???

Couldn't be an SC anyway - no chips!! Just the old reliable K-jetronic.

 

[chas3.2]

First thing is a cylinder leakege test could be piston rings, valves or valve seats, valve guides, broken head studs, costs from £3k-£4k

Charles

 

[chris.hevey]

ORIGINAL: Charles Marsland
First thing is a cylinder leakege test could be piston rings, valves or valve seats, valve guides, broken head studs, costs from £3k-£4k
Charles

(makes sucking-in-air mechanic's "it's gonna cost you" face with sorrowful headshake)

In my case it was all of the above. The pistons were flopping about like cotton reels in a toilet roll tube (well, nearly[])

Normally the only serious treatment for this is a new set of cylinders from Porsche at around £3,800. Luckily we found an engineering company that could bore them out a bit, re-plate with a fancy high tech ceramic / metal alloy, then bore them back to the original diameter but with less friction and better wear properties (apparently.) About £110 a pot including a set of matching piston rings, which seemed reasonable in comarison to a new set! I can supply details if anyone's interested.

Of course, as Phil suggests, while the engine's in bits it makes long term economic sense to replace the big end bearings etc. Extending this logic to slightly bonkers levels, I also had a recon oil pump put in, balanced the crank, polished the cams.....

At the end of it all it might have been cheaper to buy a cutesy little few year old Cayman.....