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Perkins Overheat Problem

ldavis

New member
Have a overheat problem with the Perkins 4236 on my Brewer sailing vessel. Have about 5000 engine hours. My exhaust elbow was getting clogged with mineral deposits, so I just finished a fairly extensive maintenance process where I changed out the exhaust elbow, installed a new exhaust manifold, replaced all hoses, replaced the raw water impeller, installed new belts, installed new thermostat and coolant, and acid washed the heat exchanger. Have gone over both the raw water and fresh water circuits pretty thoroughly. I have excellent raw water output from the exhaust now and the header tank coolant remains at the full level (not losing coolant). When I run the engine under load, engine temp will slowly rise for about 15 minutes until the overtemp alarm sounds (temp indicator shows under 180 degrees). I back off the throttle to idle and let it run for around around a minute or two and then then thermostat will kick in and water temp goes to 160 degrees (currently have a 160 degree thermostat installed) and the overtemp alarm will die out. I can then run the engine for hours at full load and the engine will never show an overheat condition again. But if I turn the engine off and let the engine cool down, the overheat process will occur again until I idle for a couple of minutes, etc. This happens every time.... have duplicated it around 10 times now.

So... it seems like the themostat is not kicking in soon enough to prevent an overtemp alarm. I have tried another 160 degree thermostat- same results. I have monitored the engine temps with an IR themometer. It seems that the rear of the engine is hotter than the front of the engine by 10-20 degrees. I think the overtemp alarm sender is at the rear and the engine temp gauge sender is at the front (not 100% sure of this as I haven't traced out the wiring yet).

Maybe I have air in the freshwater system ? If so, not sure how to check this or bleed it out.
Maybe I have some blockage in the freshwater system ? If so, not sure how to check this and remove the blockage.
Or something else entirely ?

Any ideas would be greatly appreciated.

Thanks,

Lee Davis
S/V Head Out
 
Did you ever figure this out ? I have almost the exact same problem on my sailboat too. About to start replacing expensive components so would love to learn from your experience.

Have a overheat problem with the Perkins 4236 on my Brewer sailing vessel. Have about 5000 engine hours. My exhaust elbow was getting clogged with mineral deposits, so I just finished a fairly extensive maintenance process where I changed out the exhaust elbow, installed a new exhaust manifold, replaced all hoses, replaced the raw water impeller, installed new belts, installed new thermostat and coolant, and acid washed the heat exchanger. Have gone over both the raw water and fresh water circuits pretty thoroughly. I have excellent raw water output from the exhaust now and the header tank coolant remains at the full level (not losing coolant). When I run the engine under load, engine temp will slowly rise for about 15 minutes until the overtemp alarm sounds (temp indicator shows under 180 degrees). I back off the throttle to idle and let it run for around around a minute or two and then then thermostat will kick in and water temp goes to 160 degrees (currently have a 160 degree thermostat installed) and the overtemp alarm will die out. I can then run the engine for hours at full load and the engine will never show an overheat condition again. But if I turn the engine off and let the engine cool down, the overheat process will occur again until I idle for a couple of minutes, etc. This happens every time.... have duplicated it around 10 times now.

So... it seems like the themostat is not kicking in soon enough to prevent an overtemp alarm. I have tried another 160 degree thermostat- same results. I have monitored the engine temps with an IR themometer. It seems that the rear of the engine is hotter than the front of the engine by 10-20 degrees. I think the overtemp alarm sender is at the rear and the engine temp gauge sender is at the front (not 100% sure of this as I haven't traced out the wiring yet).

Maybe I have air in the freshwater system ? If so, not sure how to check this or bleed it out.
Maybe I have some blockage in the freshwater system ? If so, not sure how to check this and remove the blockage.
Or something else entirely ?

Any ideas would be greatly appreciated.

Thanks,

Lee Davis
S/V Head Out
 
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