^+1....what he said
in addition........you bought a 470? much less one that didnt have glycol in the HX?
with any new to you boat, you must do all the maintenance and assume that the prior owner did none.
this includes drive maintenance (impeller, bellows, gimble, raw water pump, alighment)
engine maintenance (service the points, cap/rotor/wires/plugs, fuel filter, fluids change, etc.)
trailer maintenance (bearing service, brake service, coupler service
In addition to that, the 470 has some unique issues
first, its an open deck aluminum block with an iron head. any over-heat more than 10 degrees will guarantee you need a new head gasket
second, the cam snouts were never hardened, so the impeller used as a circulating pump tend to wear the cam snout and leak coolant into the oil
there was an upgraded heat exchanger that came out to try to help with the first issue.
since you bought a 470 that is leaking coolant somewhere, you need to find out where (before you ever think of using the boat again). you should drain the cooling system, then do a pressure test. you may need to get the HX repaired. you may need to replace the head gasket. you may have a lot more things to do.
