Years ago I got defrauded by a guy selling a 1 ton chevy with a 400. He had bad rings, not bad enough that it smoked a lot but still bad, it fouled plugs every 3-4K. So he just replaced the plugs before listing it for sale. Also the 2nd fuel tank would leak out in a steady stream….
Naive me didn't think about a compression or leak down test (most people don't) and who would fill the back gas tank to check it?
So I got taken and ended up selling for a multi thousand dollar loss when my mechanic said it needed a rebuild.
It happens. Sucks but thats the used game…
I'm thinking I'd have gone with a used engine for a few hundred rather than losing thousands on selling the truck with a bad engine. I don't know how long ago that was but used Chevy small blocks used to be a dime a dozen in my area.
That was 2 of about 5 issues he hid. Before OBD2 and not easy to identify.
The alternator was going out so he just charged the battery before I test drove.
It had been repainted and within 3 months rust started appearing on all the typical chevy square body places… both sides.
The main leaf spring on the drivers side was cracked in half and skillfully concealed with a generous amount of spray can undercoating.
The truck was dual fuel, propane and gas, but the propane hoses ended up leaking and one of the two tanks was too rusted (under the paint) to pass the necessary certification.
It went on and on… wasn't worth keeping it and I had no mechanical skills to change out engines.