Re: Onan MDKAV vented loop
Danny and Yvonne SIMMS
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Hi Paul, I had the same issue with valves needing replacement. The cause was in the exhaust elbow where the salt water cooling line entered the elbow. I dont know if the elbow on my Kubota was original Amel install. A previous owner replaced the Onan with another genset which uses the same Kubota power unit. The elbow is of stainless steel and the water enters through a tube on top of the elbow. The elbow looked fine but I didn't realise that the tube was supposed to continue internally an inch or two to carry the discharge away. This internal part had corroded off. In my innocence I replaced the valves and happily carried on. In an incredibly short time the valves had rotted again. I then looked further and took advice. When a diesel engine stops it give a little cough sucking exhaust gasses back. Because that tube had corroded off that cough carried salt water back into the cylinder head. I replaced the elbow and some years later all is still well. My venting loop is as yours is. I would suggest you check your exhaust elbow.