Why is my HD25 overheating?

[gjonz]

Take the front of the gear case off and remove the prop shaft. IIRC though once the front of the gear case is off that grommet should come out, but the lower unit must be off and water tube out of the grommet.

It’s all kind of interlocked.

[shane-r13]

Ok I will give that a try. Thank you

[shane-r13]

Well I just cant figure this thing out. Took it all apart bottom end off, head off, removed water tube and grommet. All looks clear and blowing air in all passages is non-restrictive. Also ran a small wire through the passages i could. When removing the screw below the head it is pumping water. Just a small dribble. Honestly my new impeller i have does not seem like there is alot of play side to between the housing. hard to explain i guess but the passages seem very small. Although the impeller it self is smaller than the old one and actually fits snuggly onto the concentric rotor. I guess i’ll just keep farting away slowing until i figure it out or smash it into pieces from frustration for scrap metal. I’ll post some before and after pictures of the mew impeller if i can remember to take phots when its apart again.

[nabmd]

Not to overlook the obvious, but does the cam have the pin in place? It is small and easily lost/forgotten.

[shane-r13]

Yup cam pin is there and locks it in place as it should.

[gjonz]

Great thought!

Too bad that wasn’t the answer.

So the water tube grommet has a hole all the way through that is about a 1/4 inch diameter?

Did you pull the flush out pug at the back of the power head base to see if water is pumping there? While it’s out, blow air in that passage to make sure it’s going out all the other holes.

Greg

[shane-r13]

quote gjonz:

Great thought!

Too bad that wasn’t the answer.

So the water tube grommet has a hole all the way through that is about a 1/4 inch diameter?

Did you pull the flush out pug at the back of the power head base to see if water is pumping there? While it’s out, blow air in that passage to make sure it’s going out all the other holes.

Greg

My grommet has been trimmed shorter because it was mucked up. But it has a hole that size right up into the Copper/Brass Coloured water tube. I have taken the flush plug out and while its running it will dribble water. When I has the bottom end and head off of it i was able to blow through the flush hole and had air come out the bottom end at the grommet. Anywhere else i should feel air from? All passages seem clear and I have been able to pass air and a wire through them.

I suppose all this could possibly be because the grommet is now slightly shorter. I don’t suppose they are readily available?

The ONLY thing i haven’t taken off is the carb since its combined with the exhaust i believe it its. I have had it off once when i rebuilt the carb and noticed nothing wrong that stood out but i also wasn’t exactly looking. I think that will be my next step.

I also have to upload pictures here because one is worth a thousand words and i haven’t taken any since first disassembling.

Unfortunately I’ll be heading out of town fishing for a week soon and then I’ll be starting my schooling as a machinist so this may go onto the back burner for a few weeks. Thankfully its not my main kicker motor or anything.

Shane

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[aquasonic]

" I have taken the flush plug out and while its running it will dribble water."

Ok, so if everything is right with the pump, grommet, elliptical/pin, water pump housing, and water tube, the motor should spurt water out of the flush plug for several feet. That should happen regardless of any possible blockage in the powerhead or exhaust cover. The flush plug is the "first stop" for incoming water.

After having problems in the past, with the water tube grommets swelling up and blocking cooling water, I now make it a practice to always change the grommet when changing the waterpump on HD and TD models. After all, the old grommet is also around 70 years old. A new grommet will remain open, and also seal better within the channel that it sits in. It makes a big difference. The part number is 300582. http://www.marineengine.com/newparts/pa … OMC0300582

The only other thing that comes to mind is that some of the aftermarket pumps are made too thick and can bind up in the housing. I have also seen pumps where the "piston" at the top of the pump binds up in the channel. Hope this helps.

[shane-r13]

Thanks for the link. That’ll be ordered ASAP. Cant hurt to replace everything you can as like you said its 70 years old.

How do you know if a piston pump is to thick or too tight in the channel? To me it seems snug, it will slide up and down but with a bit of force though. I always thought the gaps side to side were not that large but have been afraid to modify it since the original is crap and this is all i have. Maybe I’ll order another pump so i can experiment with one of them.

Shane

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