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Old 07-02-2013, 06:37 AM
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JimN JimN is offline
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Originally Posted by jessejames View Post
Anyone know if you can run your boat without the MDC plugged in?? Obviously the gauges won't work.

I got one from Medallion, but I forgot it at home and already drove up to the cabin for the week. So just wondering if I can drive without it for a day until my wife comes up and can bring it.....Anyone try it??

Also...check this thread out.
It sounds more feasible that the air leak allowing water up to diaphram is cause for failure than the freezing. It just doesn't make sense why some years and some boats are fine with not draining, and then 1 year you aren't. It also makes more sense that the tubes are full of air and the air gets compressed by the water at the pickup. This would also mean that they drain on their own and if they didn't, then the MDC still would not be affected.

Question is now....Why do they leak, and how do you prevent that? Especially if I'm putting on a new one, how do I know the leak is fixed and not going to happen again?
They leak because they DON'T always drain on their own. It's not a thin tube going from the transom to the dash, there's a larger brass cylinder called a ballast that kind of softens the pressure from the pitot(s). If it isn't drained, and this IS part of general maintenance whether anyone wants to think it should be necessary or not, the water can eventually fill the ballast. When that happens, the thin diaphragm in the speedo or MDC fails and at that point, there's nothing keeping it from working its way to the MDC or speedo. The part in bold type above is accurate WRT the principle behind these.

The only way around this is to use an electronic pickup that never sends water to the speedo or MDC.

The only way to prevent this is to purge them of water, periodically. Since it takes almost no time, I don't understand why this is such a common problem. Blow out the lines from the front, connect the MDC and it will work as long as the diaphragm in the MDC is intact. Until you install the MDC, stick a golf tee in the end(s) of the lines so water doesn't fill your shoes (drip on the floor under the dash).

You should be OK if you don't have the MDC.
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