Assuming the engine is recovered on a platform at sea similar to SpaceX, could it be refurbished and reflown at a low cost? Would the coking, corrosion, and other problems be any worse than that in Merlin 1? Could they deal with them in the 60s and 70s? Have any detailed studies been done?
I found a definitive statement from one of the engine designers, Robert Biggs:
The only reason this was a non-reusable engine was it was non-recoverable. If we could have recovered it after a flight, it would have [been] reusable.
During testing, one engine was started 20 times, another 34 times.
According to Henry Spencer on this yarchive.net posting:
almost any regeneratively-cooled liquid rocket engine is reusable, even if it was built for expendable vehicles. The design requirement for the F-1 was 20 starts and 2250s of firing; as part of the test program, six of them accumulated over 5000s each.
That design requirement would allow for 15 full-length Saturn V first-stage burns. Between-flight cleanup might be more difficult and expensive than the Merlin since it wasn't designed specifically for reuse, and the engines are individually much larger and thus more expensive to handle, but it would have been feasible.
I can't find a reference now, but there was a proposal for a Saturn V derived booster to have the four outer engines of the first stage drop off partway through the first-stage burn to reduce weight once enough fuel had burned off. Those could have been parachute-recovered, refurbished, and reused.
fectin has it- Physically reusable, practically, not worth it.
Physically, the metals involved were pretty much kept within their operating limits, and the bearings might also be within their lifetimes (or overhaul-able).
Practically, the assembly was not intended for long life, streamlined field ops, and TCO (total cost of ownership). The Apollo unspoken motto was “waste anything but time”, and anything that did not help the mandated schedule was de facto hurting the schedule, and was to be cut.
In particular, fuel was wasted. This was the Sixties, peak US light oil had not happened yet, and the Arab nations were still getting their footing after World War II/decolonization. Therefore the petro-fuel was (in the grand scheme of things) cheap, and treated no better than monopoly money. This was also a first-stage engine, so the payload penalty of less-than-perfect efficiency was tolerable if not desirable.
The wasted fuel (partial combustion) kept the engine cool, but left carbon deposits on surfaces. If you think scrubbing the grill is annoying, try scrubbing an assembly of multiple, giant garbage disposals and a giant fireplace. There’s a reason chimney sweep was a profession. A limited amount of deposit thickness is insulating, and tolerable if not perhaps beneficial. So running an engine test of limited duration produces tolerable carbon ‘fouling’, if understood and controlled. A long engine run, however, implies an engine teardown and scrubbing, since the consequences would be staggering.
Nowadays, we have higher-temp alloys, and tighter tolerances on the kerosene. Engines can now run more efficiently, leaving less soot and gunk. Not so in 1967.