Steam at WOT

[RJJ]

Hi folks

Her engine otherwise starting and running perfectly, but a small amount of steam was noted at wide-open-throttle, on one of the slightly cool days recently. Nothing at cruising revs (2200).

Based on the following Steam out of exhaust

...it doesn't strike me as a matter of concern?

A slightly odd one in that we were on a seatrial as I am selling the boat. I don't wish to treat the buyer unreasonably but nor do I want to accept there's a significant problem...if there isn't.

He also noted there were bubbles being drawn up the raw water inlet...I have always seen bubbles being drawn up the raw water inlet under water and assumed they are a combination of turbulence and the impeller working well (given no leaks at the seacock or any of the hose junctions/strainer).

He is getting an engineer to check it over, but I wanted the view here first. Thoughts welcome, thanks.

Engine is D2-55. I replaced the exhaust elbow 2 years ago, plus c.250 hours, so it really shouldn't be that. She was relaunched with a clear saildrive leg the day before the seatrial.

 

[Stemar]

A bit of steam when flat out strikes me as pretty normal, especially on a cool day with high humidity. As long as there's plenty of water coming out, it wouldn't bother me if I were buying.

 

[dankilb]

He also noted there were bubbles being drawn up the raw water inlet

Strange thing to comment on, IMO - that’s one of the ways I know ours is working (if my head’s in the engine compartment and I can’t be bothered to climb out and check the exhaust!)

(… that’s assuming he means the strainer? We also have a section of clear hose in the siphon loop and that normally runs bubble free, but if it didn’t - and wasn’t leaking water - I’d still think nowt of it)

 

[RJJ]

Strange thing to comment on, IMO - that’s one of the ways I know ours is working (if my head’s in the engine compartment and I can’t be bothered to climb out and check the exhaust!)

(… that’s assuming he means the strainer? We also have a section of clear hose in the siphon loop and that normally runs bubble free, but if it didn’t - and wasn’t leaking water - I’d still think nowt of it)

Mmm....not sure if he meant the siphon loop....but I agree, I am comfortable with bubbles in the water flow. if there's plenty of water at the exhaust and the alarm isn't going off, and no steam at cruising revs....I am struggling to see the concern.

 

[Refueler]

Is it really steam implying large amount or just the small wafts that generate from the warmer manifold at higher revs ??

My exhaust always has some 'wafts' of white vapour once you increase out of mid throttle.

This is at about 40% throttle .....

Yes I have a large water volume passes through my system - I have inlet full open instead of controlling flow as manual advises. Reason being that I do not wish to risk running at higher than the RAW WATER advised temp. Running higher can cause RAW WATER to deposit salts and other in the cooling channels.

 

[RJJ]

Is it really steam implying large amount or just the small wafts that generate from the warmer manifold at higher revs ??

My exhaust always has some 'wafts' of white vapour once you increase out of mid throttle.

This is at about 40% throttle .....

Yes I have a large water volume passes through my system - I have inlet full open instead of controlling flow as manual advises. Reason being that I do not wish to risk running at higher than the RAW WATER advised temp. Running higher can cause RAW WATER to deposit salts and other in the cooling channels.

It's about the same as your photo.
. But at full whack after a minute or so. Nothing seen after 30 mins of cruising revs.

My usual (hugely experienced) engine guru thinks it's fine, his view "you're not supposed to use WOT except to e.g. get out of the way of a ship, and then for a short time. If no overheat, and nothing seen at normal revs, it's not even nothing to worry about. It's nothing".

Thank you all for your responses. I am close to 100pc persuaded there is zero concern....anyone disagree?

 

[vyv_cox]

It's about the same as your photo.
. But at full whack after a minute or so. Nothing seen after 30 mins of cruising revs.

My usual (hugely experienced) engine guru thinks it's fine, his view "you're not supposed to use WOT except to e.g. get out of the way of a ship, and then for a short time. If no overheat, and nothing seen at normal revs, it's not even nothing to worry about. It's nothing".

Thank you all for your responses. I am close to 100pc persuaded there is zero concern....anyone disagree?

The notorious steamers are Bukh DV20, probably a combination of elbow design and only having a 1/2 inch raw water supply seacock. They steam at only moderate revs but are renowned for their long life.

 

[roaringgirl]

Sounds like a tyre-kicker to me.

 

[Stemar]

Either ignorant, but has read a few things that have scared him, or, as roaringgirl says, a tyre kicker

 

[colhel]

The engine takes the coldness from the water to keep it cool. What your left with is warmer water than when it went in, and that can produce visible steam.

 

[Refueler]

Either ignorant, but has read a few things that have scared him, or, as roaringgirl says, a tyre kicker

Probably read a few YBW posts !!

 

[jwfrary]

Perfectly normal, cat c18s produce so much steam on thier exhausts in some installations, you can see the steam before the boat!

 

[neil_s]

My DV20 does it if the bottom is fouled - temp gauge says normal, though.

 

[Stemar]

My DV20 does it if the bottom is fouled - temp gauge says normal, though.

Figures. The engine's working harder, so it's producing more hot exhaust gases, but much the same amount of water flowing through, so it gets heated more in the exhaust, but it isn't working hard enough to get noticeably hotter