motor heating up at higher rpms
 

the motor runs fins at full throtle but after a few minutes the engine starts to heat up a little to much and then i back it down and it colls back down again
the engine is a 72 mercruser 188
i did notice there is a 1and a half inch hole in the flex hose going into the lower unit could this be a problem??

sounds like your flow is being restricted somewhere, follow the loop. Including poss bad t-stat

Also check your heat exchanger. I know that the early 3.7L's came with a smaller heat exchanger that had problems with overheating. Also how old is your exhaust elbow where the raw water dumps out? If it's more than 3 years old it may be getting blocked up. Check for leaks first, and then look for flow restrictions. Also check your impeller in the outdrive, they are known to spin the hubs at high RPM's.

is it hard to get to the impeler

Not real hard, just a few basic hand tools and some muscle power.

Tell that to MJ and Bigshrimpin!

That's hittin below the belt for old MJ.:clap:

:cen::cen::cen::cen::cen::cen:

188's are 302 Ford engines, make sure the belts are OK, if the belts get loose on a ford, the engine will over heat at higher rpms. Obvioously, check the impeller in the lower unit if the problem persist

there is a little residue from the belt

how would i go about back flushing from the thermastat

Spare is right, I was thinking the 488 4 cylinder. My bad guys, I'll take my beatings now.

thanks for the help guys i got the impeller done but the trick was to get the shift linkage hooked up right the first time i thought i had it was all reverse the second nothing the third lower unit wouldnt go on the last time an employee i call rusty bucket thought it would be easier to just go in from the transum side of the lower unit to line up the shift linkage