Urgent advice needed-Universal steaming

[Quadrille in JB]

Just left the dock on first leg of Bahamas cruise. Heading for Lake Worth prior to crossing.
The M-30 Universal is steaming out the exhaust. It’s never done this before. Engine temp is normal; 170 F on gauge and temperature gun shows 155F over engine. Water flow looks good. Sea strainer is clean, just checked it. Boiled out the heat exchanger 2 months ago and we use the boat every week.
Any ideas? The admiral is pretty concerned about this abnormal behavior. If there’s something I can do to remedy this, now would be a good time.
I’m a decent mechanic, but I haven’t had a lot of problems with my small marine diesels so not a lot of experience here.
Thanks in advance.
Bill

[jkishel]

Are you sure the engine is producing steam? That can’t happen with the engine and exhaust at normal operating temperature as you indicate. Could you be seeing white smoke, not steam? White smoke is unburned fuel. Unburned fuel is most often caused by contaminated fuel (water), low compression (engine often doesn’t start easily or run well), or a restricted mixing elbow (symptoms similar to low compression). Did you recently buy fuel?

[Quadrille in JB]

Thanks for the prompt reply
We just bought fuel from a new source but siphoned in from jerrycans. We don’t fuel directly from dock anymore since getting ~2gal of water ln WPB.
No water visible in Racors so it must be small amount.
Do you think it’s ok to run like this? We cruise at 1500 rpm when not sailing

[gonesail]

do you check the exhaust elbow?

[Quadrille in JB]

Another possibility
How can I check it without disassembly.
At this stage I don’t want to break any bolts off
What’s the downside of a slightly plugged elbow?

[GordMay]

It’s first necessary to clarify the difference between steam and white smoke.
White smoke will linger behind the boat for several boat lengths, while steam will dissipate quickly - normally within 5 to 10 feet.
White smoke is almost always caused by oil entering the combustion chambers and burning along with the fuel mixture.
Steam will normally be caused by one of the following conditions:

1) In the cool part of the season, it's rather common within our northern operation locations for people to report a "vapour" coming out with the exhaust on their boats. This vapor is simply a matter of warm moist air cooling and condensing behind the boat. The problem goes away as soon as the weather warms up a bit.

2) Early model cooling systems will create a small amount of steam until the engine gets fully warmed up. While an early model engine is still cool, most of the cooling water is being recirculated, leaving an insufficient amount of engine cooling water to be discharged into the exhaust system to cool the hot section, and what water does enter the exhaust system turns to steam. As soon as the engine warms up, more water will be discharged to cool the exhaust system, and the steam should dissipate.

3) In both early and late model engines, cooling water flow may have reduced due to a defective water pump or a restriction in one of the cooling hoses, so that there is no longer sufficient water flowing through the engine to keep the hot section of the exhaust system cool, and a small amount of steam may be developing in the part of the hot section where the engine cooling water enters the system.

4) Steam will sometimes be created as the hot section slowly clogs with precipitate, where the engine cooling water enters the hot section, usually just above the inlet to the water lift muffler.

NOTE: In both (2) and (3) above, the creation of steam may be somewhat exacerbated if the hot section was recently wrapped with an insulating material, since the insulating material will result in a hotter temperature within the hot section.

5) The most serious scenario would be steam caused by a small amount of water leaking into the exhaust manifold through a crack in the block, head or manifold. Steam created by a small crack in one of these cooling water jackets will usually elevate exhaust back pressure within the manifold or the rest of the exhaust system, which will, in turn, cause a very thick caramelized brown goo to form on the stems of intake valves. We have several cases on record where intake valves have stuck open in only 5 to 10 hours of operation.


Sorry, I don't recall from where I 'stole' this explanation.

[Quadrille in JB]

Thanks Gord.
I think we’ll motorsail to WPB and see how it goes to there.
No bubbles in the coolant and no change in coolant resivor level

[jkishel]

Originally Posted by Quadrille in JB

Thanks for the prompt reply
We just bought fuel from a new source but siphoned in from jerrycans. We don’t fuel directly from dock anymore since getting ~2gal of water ln WPB.
No water visible in Racors so it must be small amount.
Do you think it’s ok to run like this? We cruise at 1500 rpm when not sailing

I would first go through the cooling system to eliminate that as the cause. Make sure the raw water through hull is clear (we’ve had lots of seaweed in FL lately). Check the raw water pump impeller (just replace it if it’s been a while). You say the heat x has been cleaned out recently, check the mixing elbow for restriction. Check fresh water pump belt tension. With normal engine temp, thermostat is probably OK. If cooling is OK and problem persists, run engine from a jerry can of known clean fuel to see if your tank is contaminated.

[Quadrille in JB]

Recent impeller
Thanks

[Quadrille in JB]

Thanks to all for your advice
We’re about 5 miles offshore now and there’s no more smoke.
Self-curing Universal. ��
I’ll pull the exhaust elbow and inspect/clean it when we get home.

[boatman1]

Perhaps you experienced this early in the morning (getting an early start?): dew point and temperature close so you got condensation from exhaust saturated with moisture? That’s what it appears to me.

[Cpt Mark]

Originally Posted by GordMay

It’s first necessary to clarify the difference between steam and white smoke.
White smoke will linger behind the boat for several boat lengths, while steam will dissipate quickly - normally within 5 to 10 feet.
White smoke is almost always caused by oil entering the combustion chambers and burning along with the fuel mixture.
Steam will normally be caused by one of the following conditions:

1) In the cool part of the season, it's rather common within our northern operation locations for people to report a "vapour" coming out with the exhaust on their boats. This vapor is simply a matter of warm moist air cooling and condensing behind the boat. The problem goes away as soon as the weather warms up a bit.

2) Early model cooling systems will create a small amount of steam until the engine gets fully warmed up. While an early model engine is still cool, most of the cooling water is being recirculated, leaving an insufficient amount of engine cooling water to be discharged into the exhaust system to cool the hot section, and what water does enter the exhaust system turns to steam. As soon as the engine warms up, more water will be discharged to cool the exhaust system, and the steam should dissipate.

3) In both early and late model engines, cooling water flow may have reduced due to a defective water pump or a restriction in one of the cooling hoses, so that there is no longer sufficient water flowing through the engine to keep the hot section of the exhaust system cool, and a small amount of steam may be developing in the part of the hot section where the engine cooling water enters the system.

4) Steam will sometimes be created as the hot section slowly clogs with precipitate, where the engine cooling water enters the hot section, usually just above the inlet to the water lift muffler.

NOTE: In both (2) and (3) above, the creation of steam may be somewhat exacerbated if the hot section was recently wrapped with an insulating material, since the insulating material will result in a hotter temperature within the hot section.

5) The most serious scenario would be steam caused by a small amount of water leaking into the exhaust manifold through a crack in the block, head or manifold. Steam created by a small crack in one of these cooling water jackets will usually elevate exhaust back pressure within the manifold or the rest of the exhaust system, which will, in turn, cause a very thick caramelized brown goo to form on the stems of intake valves. We have several cases on record where intake valves have stuck open in only 5 to 10 hours of operation.


Sorry, I don't recall from where I 'stole' this explanation.

I love your explanations! Always learning. Thanks

[deblen]

Originally Posted by boatman1

Perhaps you experienced this early in the morning (getting an early start?): dew point and temperature close so you got condensation from exhaust saturated with moisture? That’s what it appears to me.

I agree. Suggest you run at 22-2500 RPM for a bit & see if temp stays under 190F. Is ther a normal amount of water coming out the exhaust? Check the suction line from the seacock thru the filter & to the raw water pump intake.Sometimes the hose can collapse or kink./ Len

[Quadrille in JB]

Update
We motorsailed to Lake Worth Inlet without a problem at about 4.5 kn against the gulf stream. No problem. The IR temp guns (2) never read above 166F.
Fuel consumption was 15 mpg. Not bad, I don’t think.
Off to West End tomorrow I hope.
Thanks again for your all’s help.
Bill in JB

[jmschmidt]

Stick you hand in what you are calling steam. Does your hand become oily feeling? Slightly oily could be a bad injector or two. Not too bad a thing. Heavy oiliness could be blow-by lub oil. Not good.