I just bought a 2001 Elwell Parker 18k capacity forklift with a Vortec 4.3 motor that has a lot of rust in the block. I was thinking of flushing it in reverse with a expanding hose nozzle then hooking up a coolant pump and circulate some CLR through it for a few hours. Any better ideas?
I needs to be warm, so you may as well run it, use its own water pump and save the third-party plumbing and the cost of hot water. I HAVE that hot water, and handy. Few do.
Water.. to reduce the amount of crud the chemical has to deal with.
Packaged radiator flush, ELSE Arm & Hammer "washing soda"
Water again. Have a care not to chill-crack.
Repeat if need be. More time, each of more times is better than stronger chemistry.
Expect probable leaks, radiator or white-metal parts, such as water pump and thermostat housing. Also heater system on passenger cars, but not here. Transmission lube or hydraulic oil heat exchangers can also develop leaks - if even it has such.
Repair or replace those, the thermostat itself, relevant gaskets, and all hoses BEFORE going over to anti-freeze.
Less mess as well as cheaper that way.
NB: Oil & trans fluid changes are best done hot as well, but be wary of scalds. Very wary.