White smoke from diesel engine

[killick]

My 12 horse power two cylinder Westerbeke diesel motor is emitting white smoke at full power but reverts back to normall at lower revolutions. The propeller is fouled witch may possibly have an effect. Do I have anything to worry about and if I do, can someone please suggest what is to be done.

 

[Marsupial]

Is it smoke or is it steam? The fouled prop "should" result in black smoke at high RPM unless there are timing issues, so we need more info.

First CLEAN the propeller.

 

[sailorman]

My 12 horse power two cylinder Westerbeke diesel motor is emitting white smoke at full power but reverts back to normall at lower revolutions. The propeller is fouled witch may possibly have an effect. Do I have anything to worry about and if I do, can someone please suggest what is to be done.

Its working harder, what is the coolant temp, is it higher than normal if so the raw water injection will be higher & with lower ambient you might notice this as mist / steam

 

[jimi]

It probably means the engine has elected a new pope, stand by for a change in behaviour!

 

[Cappen Boidseye]

White smoke normally means unburnt fuel, as in neat deisel vapour, some really old diesel engines through out white smoke until they warm up and start to burn the oil. That is very unlikely, it is probably steam. As somebody else mentioned, diesels tend to belch black smoke when working very hard as too much fuel is injected and ends up being burnt badly.
Blue smoke is burning engine oil and is a bad thing.

 

[stuey_two]

A restricted flow of raw water through the engine can give the symptom you describe - the water can boil in the exhaust system.
Happened on my boat when the exhaust inhection elbow got clogged!

 

[theoldsalt]

It is important to determine whether it is white smoke or water vapour as the cause and therefore cure will be different.

Water vapour (commonly and incorrectly called steam) is common in cold weather but especially in raw water cooled engines if there is restiction in the water, and even in the summer. As previously stated due to water tending to boil in the hot exhaust. The restriction can be in the exhaust injection point (easy to cure) or in the engine water jacket (far more difficult to cure)

Flow restrictions in indirect cooled engines usually result in raw water being blown back into the fresh water system and eventually overpressurising it to the point of blowing out of the pressure cap. This symptom is usually more noticeable that water vapour out of the exhaust.

I had that on my boat a couple of years ago resulting in a mixture of hot salty and fresh water mixed with antifreeze in my bilge.

 

[KellysEye]

We used to get what looked like white smoke but was the hot water condensing in cold air. If you are also getting it in warm air there may be a problem as mentioned above.

 

[quimby]

Check to see if inlet is restricted, this could show up with the pipe being compressed as the pump struggles to pull the water through, don`t ask how I know about this!

 

[NormanS]

It is important to determine whether it is white smoke or water vapour as the cause and therefore cure will be different.

Water vapour (commonly and incorrectly called steam) is common in cold weather but especially in raw water cooled engines if there is restiction in the water, and even in the summer. As previously stated due to water tending to boil in the hot exhaust. The restriction can be in the exhaust injection point (easy to cure) or in the engine water jacket (far more difficult to cure)

Flow restrictions in indirect cooled engines usually result in raw water being blown back into the fresh water system and eventually overpressurising it to the point of blowing out of the pressure cap. This symptom is usually more noticeable that water vapour out of the exhaust.

I had that on my boat a couple of years ago resulting in a mixture of hot salty and fresh water mixed with antifreeze in my bilge.

"Incorrectly called steam". That's real nitpicking.

 

[pampas]

Flow restrictions in indirect cooled engines usually result in raw water being blown back into the fresh water system and eventually overpressurising it to the point of blowing out of the pressure cap. This symptom is usually more noticeable that water vapour out of the exhaust.

Could you kindly explain HOW, as the two systems are seperate? or am I missing something!!!

 

[penfold]

Flow restrictions in indirect cooled engines usually result in raw water being blown back into the fresh water system and eventually overpressurising it to the point of blowing out of the pressure cap. This symptom is usually more noticeable that water vapour out of the exhaust.

Could you kindly explain HOW, as the two systems are seperate? or am I missing something!!!

The blockage causes the SW side of the intercooler to pressurise, which it is not designed to resist; this may force SW past whatever seal keeps the SW and FW apart, mixing SW with coolant and eventually causing an overflow.

 

[theoldsalt]

pampas,

The two systems are in the heat exchanger and usually separated by rubber end fittings attached by hose clips (see link below). The salt side can blow back to the fresh side via a failure at these rubber ends. It can also be caused by corrosion in the heat exchanger tubes causing them to fail at the higher pressure. Remember the raw water pump is a positive displacement pump which can generate extremely high pressures if a restriction occurs on the outlet. The fresh water pump is a vane pump and generates very low pressure being primarily a flow pump not a pressure pump.

http://www.ejbowman.co.uk/products/MarineHeatExchangers.htm

 

[nimbusgb]

Low flow resulting in steam or water vapour at high revs may also be a failed or worn impeller.

 

[Marsupial]

pampas,

The two systems are in the heat exchanger and usually separated by rubber end fittings attached by hose clips (see link below). The salt side can blow back to the fresh side via a failure at these rubber ends. It can also be caused by corrosion in the heat exchanger tubes causing them to fail at the higher pressure. Remember the raw water pump is a positive displacement pump which can generate extremely high pressures if a restriction occurs on the outlet. The fresh water pump is a vane pump and generates very low pressure being primarily a flow pump not a pressure pump.

http://www.ejbowman.co.uk/products/MarineHeatExchangers.htm

SO the two systems are not connected UNLESS there is a catastrophic failure of the heat exchanger seals what a surprise, the way the above is written is a very very poor description, lucky I am not marking this work it would n't pass!

There is not enough pressure in these systems to "blow" anything anywhere. Bowman should and do know better.

and for the record this is steam:- "the vapour into which water is converted when heated, forming a white mist of minute water droplets in the air."

 

[Stork_III]

and for the record this is steam:- "the vapour into which water is converted when heated, forming a white mist of minute water droplets in the air."

I thought true steam was invisible, only when cooled slightly is it visible as water droplets form, when it is actually then water mist not true steam, . Am I wrong, I usually am these days.

 

[theoldsalt]

Stork_III,

Quite correct.

Marsupial,

There can most definately be enough pressure in the raw water cooling system to "blow" raw water back into the fresh water if the raw water outlet is resticted either past the seals or via a corroded heat exchanger core.

 

[Marsupial]

Stork_III,

Quite correct.

Marsupial,

There can most definately be enough pressure in the raw water cooling system to "blow" raw water back into the fresh water if the raw water outlet is resticted either past the seals or via a corroded heat exchanger core.

NO - and because we seem to be pedantic today - you cannot blow something back that was n't flowing in the first place. IF there is a failure then there could be a flow into the fresh water side IF the raw water pump was capable of producing enough pressure and there was an obstruction in the raw water system beyond the heat exchanger. Very contrived and very rare but it does happen. MOST fresh water sides pressurise at around 1 bar some far less (and that's NOTHING to do with the fresh water "pump" or circulator as we used to call them) its about expansion as the water - oops coolant, heats up. The raw water pump - yes we can call it a pump - on a good day might produce 2 bar so there could be a flow IF this IF that and IF the other.

as for steam - well look at a few dictionaries - I did, you can cherry pick any definition you like.

As for OP we need to know if what id coming out of the exhaust pipe is oil or water - is that OK?

this is worse than trying to converse with academics - must find another forum.

 

[Melleman]

We used to get what looked like white smoke but was the hot water condensing in cold air. If you are also getting it in warm air there may be a problem as mentioned above.

+1

It slowly increase from below+12C watertemp.
On our Perkins 4.108
First time in +3C watertemp I thought it was the head gasket.

 

[vyv_cox]

NO - and because we seem to be pedantic today - you cannot blow something back that was n't flowing in the first place. IF there is a failure then there could be a flow into the fresh water side IF the raw water pump was capable of producing enough pressure and there was an obstruction in the raw water system beyond the heat exchanger. Very contrived and very rare but it does happen. MOST fresh water sides pressurise at around 1 bar some far less (and that's NOTHING to do with the fresh water "pump" or circulator as we used to call them) its about expansion as the water - oops coolant, heats up. The raw water pump - yes we can call it a pump - on a good day might produce 2 bar so there could be a flow IF this IF that and IF the other.

The conditions for seawater to flow into the coolant are encountered quite frequently, most commonly on various indirectly cooled Volvos in which it seems it is easy to misplace the O-ring seals in the heat exchanger. There have been many threads on this topic over the past few years. Coolant pressure is typically 12 psi or so, seawater is nominally at atmospheric pressure, although maybe a couple of psi to allow for system resistance. However, if/when the manifold becomes clogged with salts, a regular occurence on these engines, the pressure in the seawater side quite readily exceeds that in the coolant and the seals are overcome. The seawater pump is well capable of generating pressures ove 14 psi. Ultimately it will generate no more when the vanes deform so much that they pass but very similar pumps are used for chemical dosing at well over a couple of bars pressure.