Hi Volks, Doing a strip and rebuild or an engine I’ve had stored for a long time. Engine suffered a catastrophic failure on the M1 about 12 years ago. The car had aircon and the rubber vibration damper on the pulley failed causing a huge momentary imbalance force which snapped the M14 bolt holding all the pulleys onto the crank, including the timing belt pulley (I saw all my belts and pulleys departing in different directions in my rear view) luckily this was before the arse-hole genius who invented the “SMART MOTORWAY” concept was catapulted in greatness/infamy, so I lived to tell the tale. Anyway, stripping the motor down I’ve found some piston damage. Looks to be caused by oil starvation caused by fouling of the oil control ring which was pretty much blocked by carbon deposits from a lack of oil changes (maybe previous owner was the “SMART MOTORWAY GENIUS”). This crust of black crap is all over the inside of the engine. (Worth noting here for doubters, it’s definitely true what they say about the importance of regular oil changes). So this piston damage, I’ve mic’d the piston and it’s still round and in tolerance. Scoring isn’t as bad as it appears, it’s mostly superficial. Do you guys think if I can clean it up with some 5000 grit the piston will be useable again? This is the worst piston. Input and opinions greatly received. Cheers.
If I couldn't get replacement ones easily, I'd probably try clean them up. You'll have to start with something a lot coarser though, like 500. Are the liners scored?
Thanks Tristan, replacement pistons are proving hard to source but I’m looking.. one pot has some visual marks on the bore but running my nail over it can’t feel anything so should come out with a hone. I’ll get my bore dial gauge on it and see if that picks anything up. I’ll post then..
They're an incredibly resilient engine, last one I rebuilt for a mate looked absolutely awful inside, the bores were worn to hell , even the cam buckets were pitted! Budget was tight so I put it back together with just a good clean up, new rings, valve seals, big ends and an oil pump. It's running like a new one since, pulls like a train and low emissions.
I’ve got to agree. All four oil control rings on this engine have been 90% blocked for the lord only knows how long and damage is minimal. Engine ran fine and pulled well until the M1 debacle.
