over heating

[beatnick]

I have an 1996 grady with a 1996 mercury 225efi. Just changed the thermostats &water pump.Heading out fishing in the morning the boat runs normal.Troll til the afternoon then when running back in starts to over heat then alarm goes off.This has happened the last couple of days.I flush the motor out when i get back to the dock. Same thing happens the next day.Basically run @4200-4400 for 20 to 30 min. runs fine. Troll for about 6 hrs.runs fine . Go run in over heats.Turn motor off for couple min. the alarm will stop. Put boat in gear& run at low rpm. cools back down. If anyone has any suggestions would appreciate the help. Thanks Nick

 

[JT73]

Did you change the poppet valve on the stbd side of the engine. Also check and see if both heads are at the same temp, if one is hotter replace your head gaskets.

 

[Boats Rock]

Did you check inside the water intake grate? I found a piece of plastic bag inside mine. The mechanic at the marine said he finds everything from bags to grass in the intakes.

 

[beatnick]

Thanks for the input . Going to have the poppet valve serviced this week.Hopefully thats the problem. Thanks Nick

 

[plymouthgrady]

OVERHEATING

I had the same problem w/ my 97 Yami. After they changed the water pump, my engine would over heat at idle and while trolling. They never changed the "High Pressure Grommet" where the water enters the block. I am almost certain it is the Merc. version of the grommet which is causing your overheating.

 

[JUST-IN-TIME]

poppet

 

[gradyfish22]

I agree sounds like the poppet is shot...that typically is the cause, especially if water pumps or thermostats have been changed out.