Posted: Thu Nov 13, 2008 5:47pm

ON MY BOAT i HAVE A VETUS M,O6 ENGINE 16 H.P.i AM THINKING OF FITTING A EXTRA EXPANTION TANK ON THE ADVISE OF A FITTER, AFTER A HEATING PROBLEM WITCH NEEDED A NEW CYLINDER HEAD GASGET, WHAT DO YOU THINK, THANKS

Posted: Thu Nov 13, 2008 7:04pm

Dear John, what I think is that I would want a good technical explanation as to why an extra expansion tank is now required. If this is a narrowboat with a large skin tank then the manifold/header tank might well appear to empty itself of water as the water expanded due to heat and then contracted again as it cooled so it appears as if the engine is then under filled. However if you then ran the engine with the pressure cap OFF until hot you would see a full header tank of water. If its a heat exchanger boat I can see no good reason for fitting an additional header tank. If you want to experiment then take the engine filler cap to a motor factors (Brown Bros/Partco/Unipart) and ask for the same cap but with a rubber seal under the cap. Then fit a long hose to the small pipe stub that is fitted into the engine filler neck. Run this hose into the bottom any container - say a lemonade bottle. The rubber under the cap forms an air and water tight seal so as the expanding water lifts the pressure valve the water flows into the bottle. As the water contracts it opens the vacuum valve an draws the water back into the engine. If you have a skin tank and seem to constantly dump water I suspect the mechanic has not bled all the air from the system. Tony Brooks