Exhaust steam

[Capt Ron]

I'd appreciate a few comments on this. The last couple of trips I've noticed some steam coming from the exhaust of my 28 TE with the 300 hp Yanmar. This occurs when operating above 3,000 rpm.
I've had the boat for four years and don't remember seeing this before (I don't look behind the boat that much, usually looking forward trying to avoid boats with unpainted bottoms).
Do you think it's time to inspect the cooling system or is this a normal condition I haven't noticed?

[JackK]

I'm no engine expert but are you sure it's steam? I get a little white smoke depending on the temperature and more importantly humidity. I notice it mainly when it is very humid.

Steam would indicate to me that things are way too hot. I'm sure one of the more technical guys here will chime in.

Jack

[Mariner]

Gosh, I feel like someone asked this same question not long before.

Well, I know that seeing steam off the exhaust is pretty much the norm here in the winter. Not quite as common in the summer, but in the morning when the humidity is high, and the temperature low, I do sometimes see it.

I would be concerned by it if it's a large amount. Otherwise, I'm sure it's normal. Always check your fluids, watch your temperature, and listen for anything out of the ordinary and you should be fine.

[Maye Marie]

I am running the Yanmar also and have noticed steam out the exhaust. The white vapor will dissipate quit quickly were smoke will linger a little longer. I think a certain amount of steam should be expected. You are pumping in your raw cold cooling water directly into the exhaust. If you had a problem other indications would be added to your list. You would be either running hot or your engine coolant would be disappearing.

[Merry Kate]

Capt Ron -

I've always had a substantial amount of exhaust steam, even in the hot summer. I think it has a lot to do with the sharp 90 deg turn of the exhaust plumbing directly after the raw water injection, at least on my V-drive 28 with the 5" Cummins factory elbow.

Different configurations probably behave differently, but if you've never had steam before it usually indicates reduced raw water flow. Check your raw water pump and both your engine & marine gear heat exchangers for obstructions if you suspect a problem.

Forgot to say: the couple of 28 TEs I've ridden on seem to bury the exhaust outlet in the water (and create a shower of spray) unless she's really up at the stern - seems to take 17 or 18 kts - more with a full fuel tank. When the stern's up out of the water and clears the exhaust port, you notice the steam a lot more. Maybe that's what you're seeing.

[jcollins]

Forgot to say: the couple of 28 TEs I've ridden on seem to bury the exhaust outlet in the water (and create a shower of spray) unless she's really up at the stern - seems to take 17 or 18 kts - more with a full fuel tank. When the stern's up out of the water and clears the exhaust port, you notice the steam a lot more. Maybe that's what you're seeing.

I have the Peninsular TA. I've always had steam and unless I put my tabs down my exhaust is buried as well. Much more noticable in the Fall but last weekend the water temp was 85. I still had some steam around 2900-3100 RPM. When I back down to 2500 the temp drops to around 150-160 and no noticable steam. Worried me a little at first, but seems to be normal.

[Capt Ron]

Thanks for the responses. That's what A.O.G. is all about!

[Capt Ron]

I'm replying to my own question as I found the source of the steam. Last fall when winterizing I found the antifreeze wasn't being taken into the sea strainer as fast as previous years. This spring I decided to change the raw water impeller. Half the vanes were missing! One new impeller later the steam is gone. The moral of this story...If something changes investigate and repair!

[jcollins]

I'm replying to my own question as I found the source of the steam. Last fall when winterizing I found the antifreeze wasn't being taken into the sea strainer as fast as previous years. This spring I decided to change the raw water impeller. Half the vanes were missing! One new impeller later the steam is gone. The moral of this story...If something changes investigate and repair!

Capt Ron,
Thanks for update. You just reminded me to replace mine.