Apologies for the double post... I picked up a 743 a few months ago. It always smoked a bit when starting up(dark), I just chalked it up to an old diesel... Last week after 5 minutes of use, I turned it off and heard the rad bubbling. The next day I added fresh coolant. A couple days later i was running for a few minutes and the engine quit., then I heard the coolant jug spitting out coolant and bubbling. Had it towed to a shop and they said the entire engine was full of coolant! Shop said the injectors were plugged and that caused it to quit, not the temp luckily. Head gasket? Thermostat? water pump? They're quoting $1200 just to take out the engine and diagnose what it needs and then go up from there, saying it'll likely be $4k after all is done. I picked it up for $4000 and am prepared for some work, but is this a typical issue? Are there other underlying issues usually? Is there anything else I should be doing at the same time to ensure it runs well going-forward? Any help or insight would be appreciated.