Beta Marine 20 hp BD722 engine over heating

[gary3029]

I have a problem with this engine in that the temp warning alarm comes on if I work the engine a little harder than normal. I have checked the amount of water coming out of the exhaust to ensure no blockages in the system. The book says anything less than 6.5 litres per min would indicate a problem. I managed to get about 10-12 litres/min so the drainer, pump and heat exchanger seem to be working fine. I think the problem lies in the movement of air in the engine compartment....there is none!!
It would be a simple job to put an air in/out duct into the engine compartment and fit a car radiator fan so as to move some air around.
What are the thoughts of the forum on this. Does anyone else have a problem with beta 20hp overheating?

 

[chippysmith]

To the letter... ever since new. Am fairly resigned to the fact its the ambient temperature of the the housing, albeit a very large space it will eventually get to hot. With the door slightly ajar prevent it happening. We get lots of blackening around the belt area which apparently due to the belt temperature being to hot... another indication of high ambient temperature.

Have not looked into ducting as yet, am worried about the risks of breaking the containment with regard to fire

 

[Peterduck]

Diesels consume an enormous amount of air; just multiply the capacity of the engine [around 1.2 litres?] with the R.P.M and you'll get an indication of the amount of air that your engine should be getting drawn easily into its compartment. This should help to keep it cool. Is there any point at which the engine freshwater could form a bubble which could restrict the flow around its normal path?
Peter.

 

[kds]

I would look at ventilation of the engine space. Improving this has certainly made all the difference to mine - albeit the 13.5 hp BETA.
I simply added 8 holes about 1" diameter at the top and the bottom of the engine bulkhead. (if you use a fan - don't forget you still need a suitable exit for the air.)

Ken

 

[TrueBlue]

I have similar challenges -

- with my 50HP Beta. Work it reasonable hard (up to 1900 rpm) it gets very hot; knock it back to 1750/ 1800 rpm and it's fine.

Beta deny it but methinks the heat exchanger is too small. I have two girt big 8" fans and plenty of space for the air to exit. Thinking of activating my keel cooling arrangement, though faced with obscene fuel prices later I'll probably cruise a bit slower.