25MSHC water output from upper exhaust ports at WOT

[eight_weight]

2004 yamaha 25hp 2 stroke 25MSHC

testing out a new prop today.

don't know if i just never noticed with the old prop, but fairly sure this was not happening

turning about 5800 RPM look back at the tell tale, nice and strong, same as before. However today i noted 4 streams coming out of the relief ports. perhaps not as strong as the tell tale, but they were shooting out a couple of feet.

not doing it at idle to 3500 rpm, just coming out of the pisser... punch it and get the output from the four ports.

is that normal?

pulled cowling, was able to hold finger on top, back and sides of the head for 2 seconds, spit on it, no sizzle but evaporated quickly

I am able to run this prop an inch or so higher than the old one. prop internals are the same so i dont think that i am restricting any flow...


thoughts?

[eight_weight]

So anybody have an idea of how much water should be coming out if the exhaust relief ports at WOT?

[99yam40]

I know the old Johnsons and others dumped lots of water from the idle relief ports while running, but have no idea what the 25 Yam is suppose to be doing.

I do know my Yam C40TLRX has nothing coming out of there since I got it used and it is still running OK

[zenoahphobic]

So anybody have an idea of how much water should be coming out if the exhaust relief ports at WOT?

Could be restriction lower down, from corrosion build up, or sand/ mud. Water will push out where it has least resistance. I got know idea how much should flow out at WOT namely because it is hard or not easily casually observed.

If you get no further answers I would only worry if engine is overheating, as that water discharge would not affect anything else. To investigate you will need to do a lot of dismantling and you will need to weigh up the necessity in doing this as it is not easy.

[bajakeith]

Props

I would take a close look at the inside of you "new" prop and see how much if any venting around the center hub,,,,Some of the smaller props are solid and with no venting would do what your describing......BTW,,mostly called idle relief ports

[eight_weight]

Thanks for the input guys.

The prop is identical to the one i took off. It is designed for that motor so i don't think that is causing any problem.

This engine has 6-7 hours on a total rebuild by a certified Yamaha shop. It was a 100% freshwater engine. All of the new hours have come in clean water and have not been running where it would have picked up sediment of any type...So i don't think corrosion or blockage due to sediment is the issue.

I ran it on the muffs last night and water and exhaust was coming out of the hub. if i put a piece of foam rubber over the hub, i would get a sputter of water along with exhaust from the idle relief ports. the lower casing was also draining freely around the foot.

Engine is not overheating as best i can tell, but i have a new IR thermometer that i will start to get some temp readings with.

I am beginning to think this is normal for this engine when it has a new, strong water pump, and i Just did not notice it before. Most times i would just have a guick look back at the tell tale bu the other day i was craing y neck to look at the AV plate multiple times so that is when i noticed it.