The walnut blast job was done over Christmas break. Due to holiday events, the project spanned several days. Little bits that had seeped through the valves during my work, had an opportunity to drip down to the crankcase and work their damage for days (the fumes alone will start the degradation; starting the engine finished it). After 10 minutes of running, the problem reared its head. (note that the valve seal was already possibly gunked up some from valve coking, which is the reason I started blasting to begin with; thus, the valve sealing face probably leaking a smidge more than a clean face)

So you are telling, that you let the cleaner seat in there for several days?

I did one or two cylinders on a given day. Then came back a few days later and did another cylinder. Finally after about a week, all cylinders were done. So yes, bits of the cleaner seeped through the valves during the work and laid in the crankcase for several days, wreaking havoc. I had no suspicion that any damage was being done.

Here's my obvious question ....Why not just change the oil and filter before starting ??

SF

Changing oil would not have changed the outcome. The drips that made it to the crankcase sat in there for several days while I completed the job. Their fumes were enough to start the damage.

My question, how much cleaner do you need to get mixed with oil, to get such a dramatic results? If that is the case I would be thinking about replacing the engine. Running it on the mixture that melts rubber, would destroy a much , much more than just a seals.

The engine is fine aside from the rubber/plastic. I have it stripped down to the bare block. Bearings and crank look practically brand new. Cylinders have very, very small ridge at the top. Cams, lifters, rockers all look great. There's a little bit of rubber in the turbo, so I'll tear it apart and throw a rebuild kit in it.

I'm rebuilding this baby and getting it back on the street! And it'll have more spunk than before! Good as new!

Yup! The initial realization of the problem really clobbered me pretty bad! But after the shock settled, I decided to tear into it and do what had to be done to make it run again!