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How much steam is normal

R

rmm

Regular Contributor
"Twin 1988 454s the exhaust po

"Twin 1988 454s the exhaust ports are about half in half out of the water at rest. We have owned the boat about 2 years and have always gotten the smae amount of steam from both engines, even before and after a riser and elbow change.

At cruise of 3000rpm the steam exits the ports and dissipates after about 20' or so, easily visible. Is this normal? Have scanned engines with laser temp guage and all seem to be normal.

Thanks"
 
I have 1987 350's. When I

I have 1987 350's. When I see steam coming out of mine it means they are over heating. Only exception may be when air is really cool and water is warm. Normally in the summer it indicates need for water pump impeller.
 
"Had the same problem early th

"Had the same problem early this spring, riser temp. was around 170 deg. replaced the impeller in raw water pump, problem fix. 454 FWC (closed system.)
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"Our 454 twins do the same thi

"Our 454 twins do the same thing as do my friends 454's. Seems like the cool sea water against the hot water passages causes the steam. On a damp humid day at speed, I can get a steam facial just by looking astern. My temps are a steady 160 from the reading at the thermostat housing. As for the impeller, I have 2 new Sherwood E35's installed, very clean heat exchangers and a new U-cooler port side. Both steam the same amount about 20 feet back or so on a steam producing day. I have been out enough to Barnegat Ridge in NJ about 45 miles from my Marina one way and back with zero difficulties. While I have asked this steam question before myself, it is apparantly normal for this vintage FWC engine"
 
"In the spirit of preventative

"In the spirit of preventative maintenance, how many hours should one expect to get on the impeller before replacing. I don't want to wait until it falls apart and little rubber parts get sucked into the engine. Any thoughts?"
 
"I remember that the paperwork

"I remember that the paperwork that came with the new pumps I have from Sherwood have a note on them that defines pleasure or commerical use. It further divides the separation by HIGH hours and LOW hours with no definitive designation. For light duty low hours and impeller kit is installed every year. For severe duty low hours, every 6 months. Additionally they have a MINOR kit and a MAJOR kit using an impeller and seal with a few gaskets with the Major kit being bushing, bearing, cam and a few other small parts. They recommend that these be used as little as every year to every 4 years depending on use.....Now, does'nt that clear that up?
"
 
"Thanks all. Just changed star

"Thanks all. Just changed starboard impellor and the metal piece inside, which was so worn it was destroying the impellor. Anyway that din't change the steam. Also backwashed the oil cooler.

Going to assume it is normal. Have put about 120 hrs on the boat so far with no real change in the steam. Also doesn't burn a drop of oil or coolant."
 
"RM, Sounds like everything is

"RM, Sounds like everything is normal. I wouldn't worry about the steam. I even get some here in West Florida. As long as you are checking engine temps and temps along the exhaust route and everthing is within specs thenn don't worry about a little steam."
 
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