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post #16 of Old 08-31-2013
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Re: How hot does your diesel run?

Originally Posted by tspooner View Post
The new thermostat is sitting on my nav table while I try to sort out whether I have a problem or not. Back to the boat yesterday to take some infrared readings and notes so I wasn't relying on a poor memory. The gauge has no increments between 180-240 degrees so it's a guess to what it is actually reading. After 20 minutes of running the engine @ 2000 rpm under load the gauge read approx 185, the infrared reading at the base of the thermostat housing was 175, cylinder head was 175: After 25 minutes gauge was approx 190, thermostat 181, cylinder head 180: After 30 minutes gauge was approx 210, thermostat 187, cylinder head 187. That was enough for me. I idled the motor for 5 more minutes and shut her down. There is steam coming from the exhaust and although I've noticed this in large cruising powerboats before I've never noticed much if any from my boat in the past. I've removed all hoses and ensured they are not blocked. The impeller checked out OK as did the FW cooling pump. The only thing I haven't removed is the cast iron riser where the exhaust gasses and spent salt water combine. I imagine there must be some blockage at that point. I'm convinced from what others have reported for temperatures and my own readings that I definitely have a problem.
you are getting steam from the sea water at the exhaust elbow this means it is starting to get plugged. the exhaust gas temp is constant, sea water temp is constant so the only way to make steam is to slow down the flow of sea water. if something was plugged on the fresh water side the sea water would be cooler when it reached the exhaust elbow and would not make steam. when ever there is cooling problem check the impellers first and then the exhaust elbow.


Last edited by overbored; 08-31-2013 at 12:45 PM.
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