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Crusader 350 steaming issue

foxsurf

New member
I have a 350 crusader that I recently changed the risers manifolds looked okay when I did the risers. It recently has begun to steam at higher rpms. No difference in engine temp. impeller is fine bypassed the raw water strainer to make sure it was not clogged changed out all the raw water hoses. Heat exchanger is not clogged. Still having the issue. Just not sure where to go from here. Engine runs fine just lots of steam at higher rpm(over 2800).
 
did you change the risers, the elbows, or both?

which item measured @ 175 deg?

When was the last time the oil cooler was cleaned out?

To reemphasizes Chris' point - the only way to assess the health of the raw water pump is to MEASURE its output. Looking at it is a bit better than guessing.
 
Love this one ! Took me a while to get the idea, so I can pass this along. The cooling system is not just based on the elbows and impellers. As mentioned water flow volume makes a big difference. Imagine trying to cool an iron used to press clothing by spraying water on it from a spray bottle. All it is going to do is cool to "X" level and turn some of that water to steam. If you were to flood it constantly with larger volumes of water, the likelihood of you substantially cooling the iron becomes greater and the steam effect is minimal.

Add that thought to the 3 elements of a fresh water ( assumed) cooled engine. Pumping thru the transmissions, the u-coolers and the heat exchangers all add to the potential flow reduction for the water to remove heat.

I have changed parts and pieces all over the place when I first was dealing with this kind of issue years back but it wasn't until I had a better grasp on the mechanics of the system that I have run for years, never having a cooling problem. Once certain days we do get a bit of steam but I am willing to believe it is more atmospheric conditions than cooling that becomes the root cause. At one point the steam trails were over 20 foot long and temps around 180...too much
 
Steam means the raw water flow is less than it should be. Marks call on the U cooler is right on. Its a frequent item to get blocked by zinc. Also, there are more wear items in the pump than just the impeller. The cam and the cover can each cause low flow, if worn.
 
Our '87 Tolly 34 with 7.4 Crusaders always trails a little steam at cruise. We've had the boat for 10 years and I was really concerned about it at first. Boat runs great. Even when all elements of the cooling system are fresh it will trail a little steam. IR gun shows 165 at thermostat housing and risers are cool enought to leave your hand on. Dash guages read around 165-175 depending on ocean temp which is around 55 in winter, up to about 72 in summer. Good water flow out the exhausts. I don't worry about it any more.
 
Me neither though, like you, I was once concerned. At this time of year (up north) it's normal for the exhaust to steam due to condensation.

Jeff
 
yes, I see. I'm a FL guy and never see cars with "steamy" exhaust, like up north in the winter. I suppose the same with boats. I can't detect any steam with my 454's.
 
Also, there are more wear items in the pump than just the impeller. The cam and the cover can each cause low flow, if worn.
Ditto that one!
Don't forget that there are two thrust surfaces..... (the cover flat surface and the interior housing flat surface that mirrors the cover), and these must be in near pristine condition.

When we look at/check the sea water transfer ports (the ports between man/riser), we must also look at the ports where the spent sea water enters theexhaust flow.
These too must be free flowing, and sometimes require as much or more attention.


Risers should be warm to the touch, not hot, when running on plane. I take it that the 175* was the manifolds????

.
 
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