New boat running hot

[Homebrew72]

I just got my first boat, it's a 72 fiberform with a 120 mercruiser I/O. Just learning about boats and want to make sure this thing is safe before I put it in the water for the first time. It is currently running hot(muffs and water connected) about 200 on the gauge. The temp seems to stay the same at idle or higher rpm(revd it to 2500 no change) where should I start trouble shooting? Impeller/tstat? Want to minimize unnecessary work/cost. Any help is greatly appreciated.

 

[bspeth]

Don't rev that high on muffs,I only go 12-1400 at most.Does the water stop spraying out of the muffs when the engine starts?Do the impeller first and go from there.Thats way to hot by the way.

 

[ktbarrentine]

After your impeller change, recommend you follow the guidance of mercruiser service bulletin 99-09 for proper operation while on muffs.

 

[alldodge]

I just got my first boat, it's a 72 fiberform with a 120 mercruiser I/O. Just learning about boats and want to make sure this thing is safe before I put it in the water for the first time. It is currently running hot(muffs and water connected) about 200 on the gauge. The temp seems to stay the same at idle or higher rpm(revd it to 2500 no change) where should I start trouble shooting? Impeller/tstat? Want to minimize unnecessary work/cost. Any help is greatly appreciated.

:welcome: to iboats

Did you replace the impeller in the outdrive? If not start there, if you did, what did the old impeller look like?

 

[Homebrew72]

Water continues flowing with the engine running, I'm going to check out the impeller tomorrow

 

[Homebrew72]

How do I make sure I order the right impeller kit? And doing some reading some say 90w oil in the out drive? Thanks for all the help so far.