Do your big engines have exhaust steam?

[Larry Exum]

While most of the engines running time has been at the dock since we began restoration on this Chris Craft in late January this year (2002), and the temperature was rather coolish (35 -45 degrees), we never encountered any visible evidence of exhaust smoke or steam. However, since we have progressed to the point of taking her for long lake cruises recently for some relaxation between marathon refinishing, two weekends ago, with weather dry and 75 degrees, I kept noticing steam clouds rising from my exhaust above the wake. I ran at different engine speeds and it did not increase or decrease, and it dissipated within 20 feet of the transom. But to see it for the first time made me want to drag my engine mechanic out for a cruise to check...

Before I go through that expense, what do you other big boat owners notice with steam rising from exhaust. What should I check. The engine temps were both spot on 150 degrees at higher rpm.

Any comments ?

[ken mcclure]

No experience, but at a guess I'd say it's just because the exhaust system is up to temperature.

[John B]

However, the first sign of an impeller on the way out is steam. Check your impeller in the water pump if you haven't already.

[norske2]

Blown head gasket..water jacket leaking into a cylinder is a possibilty

[THE VICTORIA]

I have owned two chris crafts in the past 25 years one a 58 catalina and newer 1972 catalina I dont know why but they both smoked a little whiteish from the exaust{especially in coller temps }never had a problem someone told me once it was a chris craft thing good luck

[ken mcclure]

Yah. I first thought of the head gasket, but he said it doesn't steam when he's idling at the docks.

If there's no water in the oil, the temp gauges are both nominal and you're not leaving an oil slick in your wake I'd think the steaming was normal. Now if the steam was coming from INSIDE the engine room, I'd worry a bit....

[Phil Young]

I'd replace the impeller. You are getting enough water through to keep the engine temp right, but maybe not enough for the exhaust. My 120 HP diesel is at the same stage, but I've just sold the boat so its the new owner's problem (he knows about it, in fact he told me)

[Ruaridh]

Its definitely not a head gasket. With enough water getting into the bores to make exhaust steam there's NO WAY your engines would hold their temperature for any time under full load. Plus the engine would probably sieze when left sitting at the dock for a week!!
The main reason for exhaust steam like you have is that the amount of raw water going through the system is only just enough and so by the time it gets to come out the other end some of it is starting to boil off.
Remember it removes all of the heat from your heat exchanges plus soaks up most of the heat from the exhaust gasses as well.
Changes in sea temperature and weather can make a noticable difference on a boat that's a bit marginal anyway.
I've seen a few semi-planing diesel fishing boats that make lots of steam all the time with no apparent ill-effects, but it can be disconcerting.
I'd say check everything that could possibly be slowing down your raw water flow: sea-cocks, inlet strainers, raw water pump impeller, oil cooler, main heat exchanger cores, exhaust manifold cooling channels, gearbox heat exchanger, anti-syphon arrangement if any. If you've recently replaced a shot impeller, be wary of bits of the old one blocking channels. Also watch out for hoses that look OK from the outside but are collapsing inside.
If all this fails and you still want less steam you'll be looking at having to up-spec something on the system.

If the problem is worsening, don't ignore it because while you might not cook your engines, a rubber exhaust hose burning through because of over-hot exhaust is potentially much more dangerous.

Hope this helps you some.
Best regards,
Ruaridh.

[ 05-16-2002, 04:59 AM: Message edited by: Ruaridh ]

[nedL]

As I remember, what you are seeing is routine. I don't think you have a problem (quite normal I'd say). Lets remember, the cooling water is being dumped into the the hot exhaust gasses (300 deg.+) right behind the manifold; some of the water is going to turn to steam.
As for a possible water pump problem, if we were to say that a couple of veins from the impellor were missing, (in this situation)it would have no effect, as the pump is still putting out more water than is needed. If it were not putting out sufficient water the temp under load would rise above the thermostate regulated 150 deg. - I'm not saying don't check the impellors, as good practice you should do that if you haven't yet. I'm just saying that I don't think they are an issue here.
Are yor engines raw water cooled? 140-150deg thermostates are what you would have in raw water cooled (salt water) engines. As I remember you are on a large fresh water lake there in GA. If the water is fresh, you might consider putting in hotter thermostates (170-180 deg) as the engines will run a bit better. Typical fresh water cooled engines (heat echanger, keel coolers, etc.)will have 180 deg. or hotter thermostates - just like a car.
I did find this pic. which if you look off the transom you can see the steam coming up out of the exhaust as you are describing.
http://www.imagestation.com/picture/sraid16/p1e531b39e6d825915ce1656356c1c642/fdf21d4e.jpg

[ 05-16-2002, 08:02 AM: Message edited by: nedL ]

[Cedarhill Boatworks]

If you replaced the impeller recently you may want to check the cam that deforms the impeller blades and makes the whole thing work. If it is worn doen it will decrease the water forced through the system.
Check the ehaust riser and mixing elbow for carbon buildup. It can be lots of fun chiseling out the carbon buildup.

[Andrew J. McGrorty]

a properly operating engine should not steam...everytime this has happened to me, on several different boats, there was something a miss in the amount of raw water passing through the system. you need to go through the entire raw water system 'til you find the cause. start at the seacock and work your way through the system. is it most likely the seawater pump, either the impellor or the pump needs rebuilding, sure. but i discovered a half open seacock on one boat too. heat exchanger tubes get fouled up,
exhaust elbows get restricted due to corrosion, sea strainers get filled with junk. for the past 2 months we have been experiencing very low water condidtions here. if you don't have enough water under the boat you can pick up enough silt to completely fill the system with muck, (i did that too , once). good luck andy

[Larry Exum]

Excellent advice gang. I will be replacing at spring layup all through hulls with new units anyway, and will this weekend check the condition of the impellers. Since I had just had both engines rebuilt heads up in October, I would have thought they would replace impellers anyway, but you never know unless you look yourself.

[brad9798]

Every inboard, through hull exhaust engine I've ever been around will steam when your are pouring 150+ degree "water" into lake water that is probably around 60 degrees.

It's NOT a Chris Craft thing, because Larry's boat has newer Chrysler 440s.

You'll notice in the summer months, when your lake water approaches 90 degrees that the "steam" will all but disappear.

It's nothing more than what you see in the winter time with cars- car exhaust is highly visible when the air is cooler ... so is boat exhaust.

Do freak the man out by telling him his impellers and/or engines and/or water pumps are shot ... good Lord.

OBVIOUSLY, Larry, you want to make sure they are all okay, though.

Do a little test- heat water to 150 or 180 degrees F. Watch the "steam" form as it cools in the air ... that's all.

Good luck, Larry. My twin 283s in my Chris Craft will "steam" 'til June ... and have for 38 years, with NO rebuild of ANY kind.

[Ken Liden]

Most of the replies have merit but the one single thing that has not been mentioned is the risers. More often than not the small water ports at the risers or riser gaskets are plugged resulting in an inadequate water flow. Often this shows up initially at higher speeds but will progressivly get worse and show up at lower speeds. I am presuming of course that your 440s are freshwater cooled and that you are running a 180 thermostat. A freshwater cooled 440 should never be allowed to run at 150 degrees. Check your thermostats and your senders or gauges.