Saturday, July 11, 2009
I've been rebuilding the wrong motor...
The piston from the motor we bought after some cleaning. There's no manufacturers part numbers. The edges and surfaces are indistinct, like somebody used a genuine piston to make a casting and came up with this knock-off.
I've been taking apart the engine from the 1986 VW Westfalia because it failed on the way up from Barra de Navidad to San Carlos (about 1,000 miles- see previous posts). As I get further into this motor, I'm finding some specific things: the pistons and cylinders don't have a manufacturer mark, and that tells me that the last rebuild of this thing was done with cheap, generic parts... the oil pump cover/seal showed signs of being reused after getting scratched up and scored... a big no-no. The cylinders are deeply scored, suggesting to me that the work in the crankcase was done with less-than-perfect attention to alignment, bearing dimensions, etc. The rebuilder smeared sealant at the bottom of the cylinders (which didn't work, and peels off to clog the small oil ports in the engine, as well as clogging piston rings and oil pumps). Disgusting.
The spare engine, however, indicates tight tolerances in the crankcase, smooth bores, clean pistons (all with the all VW parts numbers) and proper sealing procedures. So, I'm shifting my attention to the motor the rebuilder was supposed to have picked up (and refunded us $600) for the core return. It appears to be a much better engine.
The piston from the original motor. No cleaning done. Notice manufacturers part numbers. The edges and surfaces are clean, clear and distinct.
Why was it replaced to begin with? The ground strap failed to conduct enough voltage between the engine block and frame, so when the high voltage spark plugs fired (at about 1000 times a minute, each) the spark arced to the aluminum heads. Most of you know that aluminum is smelted with electricity... and that's what happened to the heads.
Below: The aluminum heads from the original engine showing melting of areas around the plugs and valves. These will go to recycling.