2006 F250TXR - Copper Tube in Lower Unit

[HMBJack]

I changed my water pump impellers yesterday on my 2006 F250TXR's (~2,400 hours).

I noticed on both Lowers, a copper tube, about the diameter of a pencil and "L" shaped. It is about 9" then bends to about 2".
In each case, the copper tube was heavily corroded and broken off and laying loose in there.

It is part #20 in this drawing >>> https://www.boats.net/catalog/yamaha...g-drive-2-f250

My engines have been running for years without this copper pipe working as designed.

What is it's purpose and should I install new ones? Thank you...

[HMBJack]

Update on the above:

I phoned a Yamaha Mechanic friend on this and he tells me the purpose of the copper tube is it cools exhaust water in the lower unit.

He says it basically keeps the lower unit cool.

I suppose I haven't had any issues since I operate my boat in 55 degrees of water 12 months a year.

Nonetheless - he suggests I replace the tube. Agreed?

[boscoe99]

Yes. Agreed.

[HMBJack]

For my own knowledge, can anyone comment on why the F250 has this copper cooling tube and the F225 doesn't?

Is it's purpose truly for cooling the gear area in the lower section of the lower unit?
For years, my engines have been running without this darn thing in place and how would one know if it has caused harm to anything.
My Lower Unit gear oil comes out clear after every 100 hours (no burnt oil).

Perhaps it is more important in warm water? Like Florida?
Curious. Thanks

[99yam40]

I do not know on those F250s, but I have read some motors had special anodes on them that directed water to help cool the hub to stop them from melting/failing from heat from exhaust I think
probably motors being run with jack plates and jacked up high

[fairdeal]

When Yamaha introduced the F250 for 2005 -
(derived from the 3.3 F225 which had been introduced in 2002)
they detailed its new features, including:



AFAIK, "propeller damper" means the rubber prop bushing...

[HMBJack]

Thank you very much FairDeal. That educates me on the purpose of the tube...

[boscoe99]

Exhaust gasses from an F250 are presumed to be higher than from the F200/F225 models. Possibly due to the variable intake can shaft mechanism.

Someone that is using their F250 at low power levels won't need the extra propeller cooling as much as someone that runs around at WOT a considerable amount of time.

The pitching of the propeller will also possibly have an effect on the exhaust gas temperatures as well.

The tube is there to help protect maybe only 10% of all motors. Yamaha does not know who that 10% is. So all motors get the tube.

[HMBJack]

Excellent Boscoe. Thank you for that explanation. This helps me understand the purpose of that little tube.

I operate in 55 degree water year round.
30% of the time I'm cruising at 75% load on the engine (4,400 RPM's) and 70% at slow speed (600-900 RPM's).

I will surely install the new tubes in my lowers but I'm not gonna be in a major rush to do so.
Seems non-critical in my case - I'm in the 90% : )

[boscoe99]

As a side note just the hellavit, early F250 gear cases has a single pair of water inlets. Ala the F200/F225 gear cases.

Ostensibly to solve a problem that a few had, Yamaha decided to change the F250 gear case so that it has a dual pair of water inlets.

And guess what, a few were unhappy with the updated gear case design.

You can please some of the people some of the time but not all of the people all of the time.

[Keithbaja]

Bosco is the man. Good info guy. As a mech/Tech with 45+ YRs in the biz. I always flush with a dual muff/Flush unit. I can write a book about Volvo penta drive flushing... LOL

[pstephens46]

Bosco is the man. Good info guy. As a mech/Tech with 45+ YRs in the biz. I always flush with a dual muff/Flush unit. I can write a book about Volvo penta drive flushing... LOL

How often would a mechanic flush a motor?