Exhaust Steam

[salfd]

Hi folks - My boat has twin Crusader 270's ( 350 Chevys ) - they are FWC and run strong in my 28 foot Scotty Craft boat. I have no running issues with them or the boat except I do get steam from the exhaust - now on both engines but much more on my Port side engine - I am just getting a little steam from starboard engine.

I checked the Heat Exchangers and they are full with antifreeze - no salt water. There is no water in the oil either. The exhaust gaskets were installed new last year and the plugs are dry. Basically the engines start on first turn warm or cold - they is no sputtering or hesitation etc.

I see plenty of water from exhausts and the salt water impellers were replaced at the end of last season.

I notice it more starting at about 2400 RPM which is my usual running speed - I don't push these engines and never run at WOT.

I did notice that the amount of steam increase a bit with higher RPMs.

The engines are mounted for V drive - the exhausts from the elbows to the transom are less than 24 inches - a very short run - and there are mufflers in that tight space.

The risers are 4" high and are on their second season - the elbows are a bit older - I figure about 3 years on them. They all have the proper Crusader gaskets.

Both engines are running at about 165 degrees according to gauges and 157 degrees according to a laser heat gun with 160 degree new thermostats.

When I take a reading with the laser gun - the elbows on the steamier Port engine, it reads about 20 degrees more that the starboard engine but they are not overheating.

So - what's the deal ? What could be causing the steam? How do I troubleshoot this?

Thank you.

 

[jtybt]

Re: Exhaust Steam

The only trouble with FWC is that your engine can read normal temps when you risers are clogged up with rust and not getting enuff water to keep the exhaust gases cool.

You may be close to having a fire in the engine compartment from the robber connectors burning up.

It's worth a check to pull the risers before something like that happens.

Just had to do an emergency fixit on the water for the same problem on a friends boat just outside of the GG bridge.

 

[salfd]

Re: Exhaust Steam

Thank you jtybt - I was kinda of thinking about the Elbows attached to the risers too. The risers are 4inches high and were brand new last year - however - the elbows are a bit older. I just reinstalled the gaskets on all riser/elbow connections.

I originally installed them wrong by punching out all the water openings in the gaskets - so this season I pulled all the elbows off and installed new "one hole" gaskets according to Crusader manual.

Last year I got very little steam - now with the the gaskets properly installed - I see more steam than ever. I also noticed a lot of boats throw steam - so I am not alone.

While the engines are warmed up - 160 degrees on the gauges - I can touch the risers and elbows and keep my hands there - although one engine is noticeably warmer than the other. The sea water returns to the risers from beneath the riser - that area of the riser is actually cool to touch.

The only other real difference this year is that I installed mufflers - I used to run straight pipes - a little load !!

What I did not do yet - it remove the heat exchangers and clean them out.

As long as I run under 2400 RPM I am ok ( it's a good running speed for me ) - very little steam and the engines are running at 160. When I crank it up to 2800 - 3000 - that's when I get the most steam and the engines start rising in temp.

What would you look at next - ( I am guessing a complete raw water check out :>(( )

 

[jtybt]

Re: Exhaust Steam

OK! For clarification...what you call risers are the spacers and what you call elbows are the risers.

 

[salfd]

Re: Exhaust Steam

jtybt - Let me try to explain my set up. The exhaust manifold on my Crusader 270 engines are of the End Type - off each engine to the rear of the engine is what I was calling a riser which is 4 inches high. Off the "riser" is what I was calling an "Elbow" and this is where the flexible exhaust hose is attached to go to the mufflers then out the transom. The set up looks like an inverted "U".

I included a link to a site showing the parts.

http://marineengineparts.com/shopsite_sc/store/html/page14.html

The raw water circulates through the exchanger then hoses to a fitting on the bottom of the "riser" ( what I was calling a riser ) then travels through the "elbow" where it meets the gases and runs through the flexible hose.

This is the best way I can describe it - With this "picture" in mind - can you determine where and why the steam is being created ? or where should I look to pinpoint the problem ?

Thank you

 

[salfd]

Re: Exhaust Steam

OK-- this seems to be a tough call - anyway - I was talking to someone at the marina about this ( he's not a "boat person" ) he mentioned that a friend had the same sort of issue - His was fixed buy pulling the boat and finding a whole colony of barnacles on or near the raw water intakes - power-washed them away - did some cleaning and re-paint and this fixed his steaming.

OK - pulling a boat out is an option but I would like to know if this is a distinct possibility that barnacles would cause the steaming - maybe due to restricted water flow ??? Any thoughts guys ??

 

[bruceb58]

Re: Exhaust Steam

It could be a water flow issue but if you can touch the risers you should be ok. Can you touch them right after running at speed?

 

[futz]

Re: Exhaust Steam

yes very mush. before you do anything have that checked.

 

[salfd]

Re: Exhaust Steam

On the Port engine - the one that seems to be throwing most of the steam - the riser/elbow combination does get warm at RPMs under 2000 - over that - I get a lot of steam and the riser/elbow combo gets pretty hot and the exhaust water is very warm to the touch - unlike the starboard engine - the riser/elbow combo is on the "cool" side and the exhaust water is pretty cool to the touch.

One thing to mention is that - last year I didn't have the issue so much - but I unknowingly modified the gaskets between the riser and the elbow - I punched out ALL the holes in the gasket. This year - reading the Crusader manual - it says to install the "ONE HOLE" gaskets between the riser and elbow - which I did - now I get more steam than I ever saw. I don't fully understand why you wouldn't want all the holes open to get maximum water out the exhaust elbows but I followed the Crusader manual anyway and installed new ONE HOLE gaskets this year - yes the hole is on top of the elbow.

I know the raw water pumps are OK - I gauged them at over 20 gallons per minute.

I had a diver friend look at water intakes for barnacles - said there were a few - cleaned them but made no difference.

Could this all be due to the rusted or clogged elbows - which is where the raw water meets the exhaust gases after going through the engine ???? - Just a guess - I am learning a lot just by going through this all with you folks.

 

[salfd]

Re: Exhaust Steam

Guys - After much back and forth - I believe we have light at the end of this tunnel..
We ( A very good mechanic/friend I should have called in the first place ).

First of all - we found clumps of seaweed in the oil cooler just after the raw-water pump - and also found a little in the heat exchanger !! Cleaned that all out. Then we pulled the Elbows and found white salt deposits in the exhaust tubes and it was wet !! This had to be where the steam was forming.
I have new Elbows coming - I will pull the heat exchangers and oil coolers and have them cleaned - I will also install Raw water strainers ! Yep - this boat don't have them --- YET !!

I am confident this will take care of the issues !! :>)

 

[jtybt]

Re: Exhaust Steam

Sorry I didn't get back to you. I guess your thread fell off the first page.

The reason the single hole gasket is used in raw water cooled systems or exhaust manifold cooled FWC systems is so the Highest point of the riser/spacer will fill with water before being discharged. At low engine speeds if the full flow gaskets were used the water would drain from the lower water passages and leave an air space at the top of the riser which would get extremely hot.

It also makes it even more critical to keep the raw water passages free of rust build-up. just a little FYI

 

[jack cameron]

Re: Exhaust Steam

Did you get to the bottom of this?
I have the same issue with inboard Stamas that does not offer much room for anything other than a little bit of hose and mini max mufflers.
I don't think there is enough distance between riser and transom of boat.Also my mufflers are not horizontal they are about 22 degree angle and i don't think they are mixing up the water and 1300 degree exhaust enough before they reach the outside air.

 

[cooter2506]

Re: Exhaust Steam

JAck start a new thread dont bring up an old post to raise your question.