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`72 Evinrude V4 Problem
The tip-off was a LOUD buzzer going off in the control unit. Then I
smelled something when I stopped (old oil burning off the power head) when I took off the outboard cover, I could tell it was hot. I let it sit for a while and cool off (buzzer stopped buzzing), and then idled back in (about 1/4 mi.) to the marina. Good thing it was a pretty cold day. Immediately I assumed it was the water pump. I didn't hear any predetonation - it was like someone was killing two of the spark plugs - on and off - until the boat got on plane (took a bit) and then it ran ok (not great, but acceptable.) I just replaced the spark plug wires and spark plugs, but it's getting dark and I am getting tired so I'll let you all know tomorrow if the problem was solved. JM LD wrote: What was the tip off that the engine was overheating? It sounds like you know what you're doing and have thought about several possible causes. I agree with you that it may be time for at least a new set of plugs. You may have gotten it hot enough to deposit a little bit of metal in the plugs that allow them to "pre-ignite" under load. Also, with the high temp, you may have broken some of the deposits off the cyl head that must be there after years of running. A good coating of deposits may not cause a problem but with high temp, you may have cracked deposits with glowing edges. In short, if the plugs and wires don't do it, I'd be ready to pull the heads "Chehalis Jeff" wrote in message ups.com... But he said all cylinder compression values were very close. If they aren't leaking down, then how is that water getting in? This is something that I have and are still considering as a possible problem. I called a local OMC repair shop and that's what they suggested - that when the engine gets warm enough and with enough "suction" on the down stroke it could draw in just enough water (from a 'partially blown head gasket') to affect how it runs under load but not enough to effect it otherwise. It's a possibility, however I would think that there should be a way to tell if that's happening without removing the head(s) and replacing the head gaskets. On the other hand, that's not really a big, expensive or difficult job so maybe it's worthwhile doing as a precaution. JM |
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