View Full Version : maristar 200 overheating

06-14-2013, 07:17 PM
My maristar, 350 engine, vdrive, overheats when under load. idleing it will stay around 160. I have replaced the impeller, cleaned all debri. It ran great for approximately 20 hours. then it started this. Anything over 1200 rpm it starts to overheat. Ive never let it get over 200, but cant figure out. replaced the thermostat. the old one looked suspect. still occurring. I just pulled the hose to the tranny cooler, raw water pickup. no screen that I can detect. Do I have to open the trainny cooler for the screen. Is it on the port side of the tranny... stumped

06-15-2013, 08:38 AM
Not sure you're looking at the tranny cooler on that boat. The cooler is inline with the 1 1/4" raw water intake hose before the raw water pump itself, and not on the transmission. You should be able to pull both water hoses (not the smaller transmission lines) and look straight through the brass cooler tubes to check for debris. Flush with a garden hose and/or use a piece of wire to clean out any lake garbage. Usually ends up being a good bit of junk and hard to miss.

Your problem does seem to be an obstruction somewhere (likely before the raw water pump) versus damaged raw water pump vanes, but check for those anyway as it being starved for water will cause them to deteriorate fast. If the intake is clear, keep tracing the path throughout the motor. May help to used one of those infrared temp sensors from Lowe's or HD to detect hot spots if you need to find a blockage in the motor cooling path (ex. headers running cool but motor hot), but hopefully you find it on the intake side of the raw water pump.