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Discussion Starter · #1 ·
My 1984 Yanmar 3GMF has always been easy to start and reliable. Went to start her a couple of weeks ago and got nothing. Noticed seawater dripping from the air intake on the engine. The mechanic blew the water out of the engine and said he felt it was most likely a bad exhaust elbow, but possible a bad exhaust manifold or Vernalift. We decided to replace the exhaust elbow, but it still seems to be back-siphoning seawater. Next, we replaced the hose going from the exhaust manifold to the exhaust elbow (which was only slightly above the waterline) with a longer hose and vented loop. Still, the problem lingers. I am closing the seacock before shutting down the engine to blow out as much seawater as possible and then I have an easy start after opening the seacock. My oil and coolant appear very clean. One mechanic says it is most likely my exhaust manifold and that I should remove and test it (but also says it might be the Vernalift). Another mechanic insists it can''t be the exhaust manifold because I''d have water in my oil and thinks I should increase the height of the loop after the Vernalift in the engine compartment (it''s barely above the waterline -- but it''s been that way for 17 years and I have a very high loop at the stern). A service mechanic at Mack Boring said it sounded like a cracked head or cracked exhaust manifold or blown head gasket. He said I''d need to test the exhaust manifold and head on the engine -- without taking them off. I think if it were the head I''d have bad oil and or coolant. Another mechanic thinks it''s most likely the Vernalift gone bad. Are there any engine exhaust/Yanmar experts out there who can help a damsel in distress with this dilemma? What should I replace/test first? (Labor is so expensive I''m tempted to just start replacing things until it''s right/ does this seem like a reasonable approach?)
 

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Discussion Starter · #4 ·
Thanks for the input Rob...I''d be curious to know how long the boat had the hose low to the waterline before the problem developed. In other words, could a hose be low to the waterline for years without any problems and then all the sudden it is a problem? In any event, I think I''m going to buy a 180 degree return and 15" of exhaust hose to raise the loop coming off my Vernalift muffler about 18" above the waterline and cross my fingers.
 
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