I've got a '78 300SD with 130,000 miles on it. I bought it a year ago. It hadn't run in 6 years. I replced the starter and retimed it. Someone had removed the injection pump and installed it WAY out of time. The compression on the #5 cly was a low (under 300 psi) and the compressor wheel showed signs of being run without proper air filtering. I assumed the engine had been dusted at some point but didn't investigate further. It ran well, with a miss on the #5 cylinder at cold idle. I drive it approx 1100 miles/week on a sustained high speed commute. Yesterday on thay way home my oil pressure started dropping in short bursts. I shut it off to find it had consumed all the oil in the pan in just 90 miles. I refilled the oil and started it. There was an impressive amount of blowby observable with the oil cap removed. I just rechecked my comression and there isn't a single cylinder over 200 psi. Oiling the cylinders brings it over 300 psi. So...it looks like it's time for an engine. I've found a few used ones, but was wondering how cost probihitive it is to rebuild them. I've got access to a boring bar and a hone tank where I work(I teach automotive). Will it cost me $500.00 in special tools and untold hours of aggravation, or are they a straight-forward rebuild? Any advice appreciated.
Thanks,
Joebiodiesel

__________________
1978 300SD
Running Biodiesel/SVO, 2 tank system
127,000 Miles