S4 Cylinder liners

[cross-eyed-twit]

During the stripdown we noticed some unusual pitting on the sides of the cylinder liners and couldn't work out what caused it. Any ideas?

[cross-eyed-twit]

Also, its amazing what results you can get when you scrub and sandblast a filthy old engine...

[lotusse89]

My liners had the same.


scratches here


I had decided to have mine recoated with Nikasil, though that didn't exactly work out since one of my cylinders came back with pits on the inside (they said it was porous). They probably exposed internal voids in the forged metal when they stripped off the old Nikasil plating.

The outside corrosion is probably burned and caked on adhesive (mixed with oil), rather than corrosion.

Edited by lotusse89 on Saturday 17th February 19:58

[cross-eyed-twit]

Interesting '89, I wasn't overly concerned as they were on the outside but one in particular was quite deep. The insides were in ok condition other than a not unsurprising small lip where the cylinder reached its zenith and the combustion had eroded a little of the surface.
Other than that they are fine and will go on ebay at some point.

The crank was in exceptional condition and after 89000 miles there were only two main bearings showing a little copper under the white metal. Geoff said its down to regular oil changes with Mobil 1. All the new stuff has gone off to be dynamically balanced and this should make for smooth runnings for the next 100,000 miles hopefully.

Edited by cross-eyed-twit on Saturday 17th February 16:25