I have a 200 Merc that I believe is overheating. The temp gauge is at the 3/4+ mark after only a little while (I just recently got the boat so I have not idea if it ever ran at a lower point). I am in Florida (it is about 90 deg. here) and I took a few temperature readings off the heads right below the top spark plugs using a digital meter with a temperature probe. I got readings of about 180 - 190 when the temp gauge was at the 3/4 mark and the heads are too hot to touch by hand for anything more than a second. I have worked part time as an outboard mechanic and I always thought that 160 was about the right temp for an outboard but the Mercury service rep. said 180-190 was o.k. I still believe the motor is getting too hot so I attempted to troubleshoot the cooling system. I have a new water pump kit (impeller and upper housing) in it and the lower housing looked to be in great shape. The motor also has new thermostats (I have tried running it with them gutted as well but this wasn't any better). With the thermostats removed there is a good full flow out of the top of the heads. Also, the pressure relief valve is staying closed. Sorry for the long description but here are my questions. Is 180-190 acceptable in hot weather or will this slowly destroy the motor? If not what is the appropriate temp. and do you have any suggestions before I end up pulling the heads for further inspection? Thanks
