AD31 overheat

[studgies]

Well we got the head gasket all done and dusted last weekend and took her out for a quick spin only to find that the temperature alarm on the engine we had worked on was coming on after running at 3200rpm for a minute or so. We did not think too much of it as we thought maybe there was an air lock or something. We got the boat back and checked for oil leaks (the reason for doing the head gasket) and found none...yeahh!!

We notice that there was no pressure when we remover the fresh water reservoir cap which was a little odd so we got a new one incase that was one of the faults. The raw water side of the system is fine, lots of pressure there!

So we took her out today to see if things were improved but alas no, engines fine at anything under 3000 rpm but as soon as you go over the port engine heats up to about 200F and the buzzer starts. We decided to remore the thermostats and give her another run but we had the same results. At the beginning of the year we took off the heat exchangers and the exhause elbows and gave them a quick clean out, I think we did a reasonable job??

So have you got any ideas for me, you lot have always come good for me in the past!! Anyone got AD31's, if so what temp do yours run at under heavy load at about 3200rpm?? The reason I ask is that we spent ages trying to source the problem with low oil pressure last year to find it was only the sensor!! According to the gauge the ports engine is running a little over the 200 mark and stbd just under according to the tech specs the thermotats only fully open at about 200F so is the over heat temp realy that close??

On the up side I now have oil free bilges!

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[muchy_]

A friend of mine just had similar problem on a Ford 6 cylinder. Would run ok at lower revs but as soon as it was opened up a bit it over heated.
He did all what you have done to cure it but to no use.
He checked the engine water pump and all looked fine until he spun it by hand and noticed that the impeller shaft had snapped, thereby not pumping the coolant around the engine.
I think he got someone to weld it back on and the engine is now fine.

Might not be this but worth a look anyhow........

Also, can you connect a hose from the water main onto it somewhere and flush it through?

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[studgies]

checked the water pump today and was fine so removed the heat exchanger and the elbow again and gace em an acid bact and a prod, all working well now, infact better than the other engine so will have a look at that one in a week or so.

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