Am I hurting my engine?

[Stumedic]

I'm running a 175 Johnson crossflow on my center console. As fuel and powerheads are expensive, I've been running it very conservatively. I just made a 120 mile round trip, burned 55 gallons of fuel, and averaged about 22knots. I kept the engine at no more than 3200 rpm. My friend tells me I'm killing my 2 season old powerhead with kindness, as it isn't happy at low rpm's. Is he right? Stu

 

[clint]

Am I hurting my engine?

You have to open it up in spurts. You will have carbon build up if you dont run it a little hard. Dont be afraid to open it up and run to 4500 or a little higher for 5 minutes or so. My 140 evenrude engine runs at 5500 at top end and I run it steady at 4500 when cruising. I worry more about a long lasting engine than worrying about my fuel cost. What is your top end on the rpm's?
Clint 8)

 

[jtexas]

Re: Am I hurting my engine?

If you hit the top of your max recommended RPM range at WOT, then it's not lugging. If you're running surface gap plugs, your manual probably suggests an alternative...use that one. Increasing spark plug gap by 005 or 01 will offset carbon buildup.
And decarb regularly.

 

[Stumedic]

Re: Am I hurting my engine?

The boat will turn 52-5400 wot, depending on the sea, and yes I'm using surface gap plugs. I have run it at 4500 for 10 min staight here and there, and it seems very happy at that rpm. Problem is here in the northeast most days you can't run that fast. Stu

 

[Stumedic]

Re: Am I hurting my engine?

And I recently started running SeaFoam in the fuel. Seems to have improved my idle.

 

[Silvertip]

Re: Am I hurting my engine?

I agree that a steady diet of 3200 RPM is not conducive to longevity in an outboard. Open it up now and then to clear things out. By all means, continue using SeaFoam. It's almost like having a "mechanic in a can". Does a great job of keeping the fuel system clean.

 

[wilde1j]

Re: Am I hurting my engine?

If motor setup is OK, you should consider propping for 5800 to 6000 RPM @ WOT. 5200 to 5400 is way too low if you want the motor to last. That translates to ~ 4'" lower pitch than you're currently running.