Has any one seen or experienced the type of corrosion to cooling system parts as in these photos?
This is from a engine I built. And sold about a year ago.
I had run the engine in on a engine stand because I did not trust anyone else to run in the cam properly. It did a total of 10hrs running as I also tuned the carb and sorted out some ignition problems.
I ran it with rain water in the cooling system and when I drained the water for shipping the water came out as clean as it went in.
The guy that bought it recently contacted me with these photos of corrosion and accused me of selling him a junkyard motor repainted to look nice.
He said he put "Quality Fluids" in the engine as soon as he got it and started it the following week and it overheated like crazy.
(I do suspect he ran it without a fan on the radiator)
But he said the thermostat (which had only 10hrs service) was caked in rust and so was the inside of the water pump.
These were like new when I put them on.
In the photos the water pump is super corroded which what looks like crystals growing on the cast iron and the brass thermostat has deep pitting into the brass.
The pump backing plate had been totally cleaned, primed and painted with engine enamel which had been on there for years before I built the motor so was well and truly hardened.
The paint on the plate looks like it was attacked by strong acid and is almost stripped off.
He told me he only ran the engine with this "Quality" coolant only a couple of times and only briefly as it overheated.
Has anyone come across corrosion like this before in a barely run engine?
What is going on? 
