# How hot is too hot for an outboard?



## Wasteman

Apologize for a probable dumb question but........ I am playing with a 1993 Evinrude 25HP. Engine fires up and runs, has a strong stream of water (off of a garden hose) but after running for a few minutes the power head is Hot to the touch. Not warm, but hot enough that you want to remove your hand after a second or two, would definately be uncomfortable if you forced yourself to keep in contact. Is this normal or a precurser to another issue? Compression is 115 and 118 respectively.

Thanks and again sorry if this is a stupid question

Waste


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## Quackrstackr

An outboard is just like any other internal combustion engine on gasoline... it is going to get hot.

They don't run cool to the touch.

I'm sure you are fine.


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## crazymanme2

You should be ABLE to touch your head without burning yourself.I have various outboards & I can touch the head on any one without getting burnt.Sounds like a water pump issue or pluged cooling system.


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## crazymanme2

Left out thermostate :roll:


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## cajuncook1

Wasteman said:


> Apologize for a probable dumb question but........ I am playing with a 1993 Evinrude 25HP. Engine fires up and runs, has a strong stream of water (off of a garden hose) but after running for a few minutes the power head is Hot to the touch. Not warm, but hot enough that you want to remove your hand after a second or two, would definately be uncomfortable if you forced yourself to keep in contact. Is this normal or a precurser to another issue? Compression is 115 and 118 respectively.
> 
> Thanks and again sorry if this is a stupid question
> 
> Waste




Your question is not stupid at all, the question and subject you bring up is always on the mind of a outboard owner. We all worry if our water pump is working and cooling the head and preventing overheating and damaging the cylinders, pistons, and ruining our precious piece of machinery.

A good investment and a piece of equipment that will give you peace of mind is a *laser digital thermometer* that you can get at Harbor Freight and other places of that sort for about $20 to $30 dollars. You can measure the temperature of the heads on side and near the sparks plugs (basically around the cylinder head).

**Some people say that you if you can hold your hand to a cylinder head for about 3sec then you should be ok......Well to me that is not a reliable method, because we all have different heat tolerance of touch. I'll tell you 140 to 150degrees feels hot to me, but it is acceptable running temps. Best bet is just to get a temp reading with the old temp sticks or a laser digital thermometer....(they or cheap enough for a peace of mind and they can also be use to measure the temperature of cooking oil when frying a turkey(but that is another story).***

I would say that the above statement is probably the case, but here is some more information if it is actually running hot.

The thermostat(T-stat) partially opens around 140 degrees and is fully open around 160 degrees. The thermostat opens and allow water to circulate around the water jackets around the cylinders to maintain temperatures less than 163 degrees.

Pee hole or water indicator is an indicator that your water pump/ impeller is working only. It does mean that your engine is properly being cooled and water is circulating around and through the water jackets.

*Things that can cause an powerhead to over heat even though you have a good stream of water coming out of the engine pee hole or water indicator.*

1. Stuck or obstructed Thermostat from salts, to junk, gunk and sand. Just bad T-stat

2. Obstructed passage to the cylinder heads caused by foreign material (bits of an old impeller), salts, and sand.

3. Sand, salts or foreign material occluding the water jackets prevent water from circulating around both cylinders.( This happened to me and I removed the the cylinder head and cleaned out the passage ways and a new T-stat. My Evinrude 6hp was back in business)

4. Swollen water deflectors in larger motors and can be caused by an overheating situation. (these are never mentioned in service manuals)

5. Blown head gasket between cylinders that allows heated compressed air in the water jacket systems and prevent water from circulating.

6. Lean carburetor adjustment and not enough lubrication to inside the cylinders, pistons and rings.

If your engine is primarily used around salt water or sandy environments then chances are that statements 1, 2, or 3 are a high possibility. (So flush your motor well after a salt water run with fresh water)

If the motor is used but new to you, any of the situations could apply.


I hope this helps you out and good luck!!!

cajuncook1


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## Zum

Good read above my post.
Umm,you say off a garden hose.(sometimes not the greatest flow)
Are you running the outboard at wide open for any length of time?
Normally you shouldn't,atleast for not that long with a hose.
You probably will get better cooling when running the outboard on your boat,not just because of the wind/air but better water flow than with a garden hose.
140-150F is pretty hot.


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## Wasteman

Thank you all for the insights. I think everything is probably OK, but I'll get her checked out anyway as well as see if running in the river makes a difference vs. the hose. I do not think I ran it long, but was not really paying attention to the clock.

Thanks again!


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## Pappy

The engine was designed to warm up at idle and cool down at higher throttle settings. A warm 2-cycle engine will idle better than a cold one any day of the week. The thermostat will usually run the engine somewhere around 135f at idle if operating properly. Have found through the years that the statement about holding your hand on it for about 3 seconds is usually correct. That's usually around 135f!


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