DF20ATL overheats in reverse!

[Zabbaskeema]

Hi knowledgeable people!
One of my two engines overheats when I go reverse.

The pilot hole still piss in reverse.

Then if I don't wait too long I can restore peace by putting it in fast idle or forward.

Any RPM no problem with neutral or forward.

Reverse is the opposite. low or high it overheats!

Is this a known symptom of something you know about?

Cheers!

Patrick

[Moonlighter]

Never, ever heard of such a thing, or seen it reported on this forum in the past 10 years Ive been a member.

You win the prize for weirdest problem ever!

Anyway,…..

what have you done so far to try to fix it?
Could it simply be trimmed out too far and be sucking air in reverse?

[briscoe]

Or, how long are you in reverse? Backing out of slip or boat trailer should be no problem. There are slots on the front side below the prop where it pics up water. Going in reverse may cause the other motor to somehow block thatvwater pick-up. When you're traveling the water is pushed into the inlet. Just a thought...

[Moonlighter]

Or, how long are you in reverse? Backing out of slip or boat trailer should be no problem. There are slots on the front side below the prop where it pics up water. Going in reverse may cause the other motor to somehow block thatvwater pick-up. When you're traveling the water is pushed into the inlet. Just a thought...

Could be onto something there….

Twin 20’s arent going to be counter rotating. So if both are in reverse, its possible that the props are pulling the water away from one of the legs???

[Murray]

To test the above theory pull the prop. off the engine that doesn’t overheat and see what happens.

[briscoe]

That's a brilliant idea, pulling the prop off for test.

[2014DF25ARS]

You said "Reverse is the opposite. low or high it overheats!" What do you mean by "low or high"? Are you referring to RPM, or to the trim level? My DF25A began overheating at idle or low RPM, but was fine as soon as I raised the RPM. Turned out that one of the vanes on the rubber impeller was broken, so the water pump wasn't producing the pressure it was supposed to at low RPM. Most people don't run engines in reverse at high RPM for more than a second or two. Could it be that you're just running lower RPM when in reverse, and a broken impeller isn't doing the job at low RPM?