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salty
Member
Username: salty
Post Number: 5
Registered: 06-2015
| | Posted on Thursday, July 23, 2015 - 01:44 am: | 
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I have a new installation of a rebuilt MD2B in a new boat that overheats. It is a fresh water cooled system with a heat exchanger (HX). The raw water side of the system works well with good flow through it. The problem seems to be air getting into the system and air locking the manifold. I don't know where the air is coming from and I have burped and blead the system until there shouldn't be any air in it. I even built a small 3 inch dia. x 11 inch header tank that mounts just ahead of the valve cover and tees off the thermostat housing to extract any air at the highest point in the system.The thermostat has been tested x2.
After running under load for awhile the water will get displaced and overflow and the engine overheat.Up until this time I can feel the cooled water in the pipe between the pump and the manifold. The water left in the tank doesn't smell of combustion gases nor is there any sign of oil or carbon.Also there is no sign of steam in the exhaust or water in the crankcase. The HX has been pressure tested x2.
Where could the air be coming from? Why doesn't it bleed off at the header tank? Will try to upload photo
Thanks |
salty
Member
Username: salty
Post Number: 6
Registered: 06-2015
| | Posted on Tuesday, August 25, 2015 - 12:04 am: |
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Update: Well I finally pulled the injectors and put compressed air to the cylinders and heard some bubbling in the header tank. I got away with retorqueing the heads which was to be a maintenance item once the engine was running but never got around to because I was chasing this other problem.Now it runs too cool with the salt water thermostat in it. |
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