www.iFourWinns.com

My 1988 4.3 OMC runs real cool at lower rpms. When I plane it off she will warm up after about 5 min and run at normal temp. I did put a new thermostat in at start of the season. Is it possible it's stuck open?

Whats "real cool"? Under 140? Depends where you boat too, cold water can make temps low. Doubt a new t-stat is stuck open on its own, of course there could be something stuck in there, forcing it to stay open. Did you ever have an impeller failure? Sometimes pieces of impeller can get stuck in there.

_________________

1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

Well, those are symptoms of a thermostat stuck open. How it's open is another story (bad or something lodged in there).

_________________
1981 Columbia 8.7
2015 Yamaha FZR - 87mph - sold
2006 Yamaha GP1300R - sold
2003 Chaparral 215 SSI - sold
2009 Stingray 195CS - sold
2000 Four Winns H180 - sold
1976 O'day Daysailer II - sold
Rick's Four Winns H180 Mods/Upgrade Thread

Its a chronic problem with raw water cooling and cast iron engines. A flake of rust (could be sand too) gets stuck in there and it won't close. I have done this to see if I can free it: run it up on plane, slow to idle, before it cools off too much tap around the thermo housing with a small hammer. That might dislodge whatever is keeping it from closing.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II