proper way to take outboard temp.

S

so

Petty Officer 2nd Class
Joined
Feb 12, 2007
Messages
170
hi all,

the clymer service manual says I should run it in gear at around 2000 rpm for at least 5 min. before taking temp at slow speed(temp should not be < 125 degree) and run it at high speed and take temp. again(should be < 163 degree).

my question is if I run it with the earmuff at high speed, wouldn't it make it runaway? what about at 2000 rpm? can you estimate rpm if without a tachometer? How do you guys really do it?

thanks
 
Pony

Pony

Rear Admiral
Joined
Jun 27, 2004
Messages
4,355
Re: proper way to take outboard temp.

You shouldnt run any engine above high idle on muffs. Most of the manuls I have read state 2000rpms on muffs as a maximum. Its difficult to measure rpms with out a tach exactly, but you dont have to be exact in this case. If it were me I would just bump the throttle A LITTLE past normal idle and let is run for the 5 minutes. Just make sure you dont walk away and always be aware of the muffs. They can slip off the lower unit. Also if they arent tight on the inlets you can leak air in and the pump will lose its prime.

After that, test the temp with temp sticks or a heat gun. Temp sticks are rated for a specific temperature and will melt only above that.
 
S

so

Petty Officer 2nd Class
Joined
Feb 12, 2007
Messages
170
Re: proper way to take outboard temp.

this may be a stupid question, but how do I find out what/where my normal idle is? is it by sound or tach?

thanks
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: proper way to take outboard temp.

Idle is whatever the engine rpm (revolutions per minute) are when the engine is running in neutral. That's normally 650 - 750 RPM give or take a little depending on engine.
 
S

so

Petty Officer 2nd Class
Joined
Feb 12, 2007
Messages
170
Re: proper way to take outboard temp.

that's what I've always thought, idle means running low rpm in neutral. But I've read a lot of posts here where people talk about idling in gear, so I guess that just means running in low rpm in gears, right?
 
S

Solittle

Fleet Admiral
Joined
Apr 28, 2002
Messages
7,518
Re: proper way to take outboard temp.

Idle is idle whether in gear or not. Many if not most OMC engines have an operating temp of around 140 degrees +/-. That is with the engine warmed up and the t-stats open. The best way to measure is with a temp gun so that you can quickly measure the temp at each cylinder and spot any hot spots - - which would indicate a restriction or possibly a non firing cyl if cold.
 
D

dsinger

Chief Petty Officer
Joined
Aug 6, 2004
Messages
424
Re: proper way to take outboard temp.

Idle will be different on ears then in the water no back pressure. You can buy temp sticks for cheap or just use your finger , one mississippi two mississippi then it hurts you are good, one miss then if hurts to hot d:)d:)d:)d:)d:)d:)
 
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