View Full Version : 1988 Wellcraft 350 Merc./260hp overheating issues.

09-28-2010, 09:21 AM
I can't figure out why the motor is overheating. I changed theromstat,impeller had out drive gone through. The boat will run fine for about 3 minutes and the temp will spike to 180+. I flushed all the lines to look for impeller pieces. Very few pieces of the impeller were found. This boat has never been in salt water.The motor only has 225 hours on it. When the outdrive was taken apart there was alot of sand in the bottom half of the outdrive. Does any know or think there could be sand in the block?

Any suggestions would help.:(

09-30-2010, 02:17 PM
risers ever been checked?

10-15-2012, 12:53 AM
Well there are a fewe things that could be going on. I would pull the lower half of the lower unit and check to make sure that the housing is good on the Impeller. (Me, I would just change the entire Impeller and housing). What happens there is the engine exhaust will melt the plastic and cause the housing to leak past. I would also pull the drain plugs and flush the block. It might also be full of sand. I just found this out with my own motor that I pull out to rebuild. It was 3/4's full of sand... Good luck!