Steam in Exhaust

[linedoctor]

I'm new to diesel powered boating, with about 10 hours on my Cutwater with the 6BY2 motor. The last time out I noticed a fairly large amount of steam from the exhaust at higher RPM's. It disappeared at lower RPM's/idle. I'd never noticed steam at all up to that point and there was enough that I'd be surprised if I'd just missed it before.

There seemed to be a decrease in power as well. The engine temp seemed about the same as always...195 give or take. Andrews wants me to run the boat and check some things for him, but it may be a few days before I get the chance. Is a lot of steam normal? Thanks!

 

[trailertrawlerkismet]

Steam in your exhaust water could be a sympton of an impeller that has broken up, however it may also be something else. A quick check is to close the water supply off to the engine, take the cover off of the impeller housing and physically inspect the impeller. I'd suggest having a flash light and a mirror so you can get as good a look as possible at the impeller fins, they should all be intact. If you've not done this before either hire someone and watch them or find a boating friend who has and have him supervise you doing the inspection. If the impeller is damaged it will need to not only be replaced but it is imperative that all the broken off pieces are collected from inside the housing. You'll want to know how to do this in the future and it's a good practice to carry a spare impeller. When the job is finished turn the water supply back on. Please let us know the end result.

 

[commander bill]

One thing I have done is buy one of these small hand held infrared "guns" from Harbor Freight. Cost less than $30 and provide accurate temp readings. I have learned to us this valuable tool when checking the engine while operating. It will tell you instantly if the plastic muffler is warmer than it should be. My Tug is the 75HP (one of kind) so my usual readings would be of no value to others on this website but scaning various engine/components while operating can give you a quick feel if something is operating out of normal values. Of course you would have to mentally factor the engine RPMs and ambient water temps into your considerations.

My tug came with the small cheap strainers on the Genset & AC. They contrasted much from what appeared to be a well made high quality strainer on the main engine. The locations were also hard to access. But with 3 1/2 years I have yet to have one clog. I found that you could buy replacements (Sea Dog brand with clear housing, stainless strainers, and hose nipples) for under $10 each from Boatfix.com . I am probably lucky because th eupper Tennessee is fairly clear water but I did operate my boat on Florida pandhandle for 3 weeks and 80 hours underway with out problem. I would suggest that someone that has no way to avoid seagrass (or other water growth such as the heavy grass found on lower Tennessee River might want to install better strainers in a more accessable location.

 

[trailertrawlerkismet]

Linedoctor:

Have you had any luck determining the source of the steam in your exhaust? If you have or when you do please make a post to let us know what corrected the situation so we all learn what to look for. Hope it is or was nothing serious.

 

[linedoctor]

Since my last post, I ran the boat and got all the readings to Andrew that he asked for. He said everything was where he wanted to see them, and suggested the steam was just from the difference in exhaust water temp vs. the lake water/air temp where I was running the boat.

When I ran the boat yesterday in 80+ degrees weather, there was very little steam and I had to actually be looking for it to see it at all. Before, there was quite a large consistent cloud, but the air temp was in the low to mid 60’s. This backs up Andrew’s evaluation pretty well I think.

I believe my perceived decrease in power was just a case of paranoia when I assumed something had to be wrong to cause all the steam.

It is interesting that no one else here mentioned seeing large amounts of steam at times.

 

[gozer7]

I have steam in my exhaust. I did destroy the impeller but replaced it. I got all the pieces I could see out, suspect some went into the heat exchanger. Someone told me they will just disintegrate over time? I bet I should try to get them out. How do I go about that?