Exhaust Pipe Steam

[4900bruce]

hi ,my boat has a 48 hp thornycroft diesel,fresh water heat exchanged.
I cruise at 21-2200 rpm .temp gauge comes upto 90 degrees as it should and stays there while motoring.all good so far
the salt water coming out off exhaust pipe is more steam than water,for some reason this worries me ,I would rather see a steady stream of hot water coming out as it has with all previouse boats.
The gear box is water cooled and exits via a seperate outlett .gear box water is warm only so have been thinking of restricting gearbox outlet so more salt water will go to heat exchanger.
any thoughts or suggestions-thanks.

[imagine2frolic]

Sounds like you need to look at your cooling system. It could be as bad as a bad head gasket, or worse. I could be as easy as an impeller too. Restricting the gearbox will only create it's own problems......i2f

[David M]

Check the flow and check your riser. The diameter may be shrinking as the metal oxidizes.

[Rex Delay]

I had a similar situation last year. Thought it was head gasket as I had gone through everything else, limped it home and it siezed on final approach to my slip. Turned out to be the impellor pump seal. Sea water contaminated the engine oil (makes for very poor lubricant), and I now have a new engine.

[4900bruce]

thanks everyone for thoughts,yes david I will check riser.salt water injection pipe going into riser may be restricted .
impellor is only ten engine hours old and flow must be good as salt water is cooling fresh water via exchanger as engine temp gauge sits perfectly on 90 degrees.
dont have a problem with engine cooling but dont like seeing steam coming out of exhaust.

[Rex Delay]

Get your oil tested for water contamination.

[fred]

Does the engine consume coolant?
If so it could be a head gasket.

After checking the coolant for oil and the oil for coolant....
Check the riser elbow, where the raw water enters the hot exhaust pipe.

Perhaps not 'enuf' water is entering the pipe to cool the gases.

Disconnect the raw water feed to the elbow, start the engine and measure/check the flow...
It should match the water coming out the exhaust pipe after reattaching.

If not the riser is corroded and clogged; holding back the raw water from the pump.

The riser may have to be replaced.
I've ever had much luck cleaning/scraping/boiling them to clear the flow....

fred

[Highlander40]

Check the raw water intake strainer and clean it.