Hi Dago By and welcome to YF
Sorry to hear of your motor problems.
Capt J ran some numbers for you, to which you'll have to add a rebuilt turbo.
Now, what's to prevent the same thing from happening to the other
engine? Need to double the dollar figure?
BTW, in 1998, Cat came out with a three-valve head (with much improved breathing and hence able to meet stricter emission standards) and a host of other improvements--including a totally electronic governor--for the 3126B which supercedes your engines.
If it were me, I'd call your local Cat distributor service dep't. and ask for some friendly advice regarding parts interchangeability between the 3126 and 3126B...at least as far as the heads go...if I were to keep the boat long-term.
Or do the least work required per Capt J and sell the boat.
See link: http://findarticles.com/p/articles/m...64/ai_21201302