Why is my HD25 overheating?

[shane-r13]

I have replaced my impeller with a new one. I’ve blown out all tubes and passages. Also removed bottom end and head and ran I wire through the passages. No blockages. When I take the screw out of the bottom of the head water does flow out but not a great amount or a constant stream. Water is also misting out the ports on the exhaust housing but not to any great amount compared to my td20. I also have added the pin in the bowl and high speed adjustment through the clean out screw. Nothing has helped. It runs for 30-60 seconds than dies and won’t start till she cools down. I can hear the fuel bubbling in the carb and it overflows when it’s heated up. What’s next? Thanks!

[gjonz]

These motors run hotter than most. BUT…

The carb is cast into the exhaust housing. There was a bulletin that certain motors…probably early ones…get vapor lock because the fuel gets hot going into the carb due to an over-sized passage at the bottom of the carb. Instructions state to put a small wire pin inside that passage and it should clear the fuel issue.

BUT…

I would pull the exhaust housing and check for a plugged water passage. Is there charred paint on the motor?

There is a small grommet that the water tube seats into at the lower unit above the water pump. I have seen them close up and seriously restrict water flow. It should be open to a 1/4 inch or so. If it’s closed up even slightly it can cause issues.

And at the back of the powerhead there is a flush port that you may want to unscrew and blow air through. It looks like a drain plug for a lower unit.

Make sure the wobbler pump is tight on the eccentric on the prop shaft too.
Hope this helps!

Greg

[shane-r13]

I’ve done all of that as stated in my first post. No charred paint. Ive removed the exhaust/carb housing go service the carb but didn’t pay particular attention to the water passages. I’ll have to pull it off again. As for the grommmet I don’t see one. There was a rubber piece that came from the water tube that was all buggered up, I trimmed a bit and can see the tube so it’s not blocked by anything.

[shane-r13]

I’ve trimmed the rough looking iece at the bottom of the water tube slightly to clean it
Up.

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[cajuncook1]

Your rotor in the picture is either wrong size/part or it has swollen over the years from grease and oil. Because it is so swollen, it does allow gaps to gulp enough water to cool your motor.

[cajuncook1]

Look at the picture I have provided for you from a manual. You see the water flow pattern and see the rotor is smaller and not swollen. The "wobbler" or rotor is moved around and gulps water forward. Your rotor is too large/swollen to allow for proper water flow and volume.

The original part number for the rotor was 300583

[shane-r13]

That’s my old rotor. I’ve since ordered a new one and yes it’s smaller and fits much better. Hasn’t helped.

[gjonz]

That wedge shaped grommet is what I was speaking of. I know you trimmed it at the bottom, but look up through it and make sure it has not swollen closed a bit. Every little bit helps. The tube may still go into it, but the hold may be swollen partially closed. Should be the same all the way through the bore of the hole.

Greg

[cajuncook1]

Ah, sorry that lead to my assumption. Did not realized you changed it out.

[shane-r13]

quote gjonz:

That wedge shaped grommet is what I was speaking of. I know you trimmed it at the bottom, but look up through it and make sure it has not swollen closed a bit. Every little bit helps. The tube may still go into it, but the hold may be swollen partially closed. Should be the same all the way through the bore of the hole.

Greg

Ok I’ll take a look up inside. I did run a wire up it and it went. How do you peer up it? The prop shaft seems to be in the way. Should I remove the foot from the mid section?

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