Volvo Penta MD7A - Reverse Gear Box

[jmaue]

Who has winterized their MD7A and drained the water from the reversing gear box? I found the Screw?? on the bottom side. Did you refill with winterizing fluid? Do you refill with water in the spring?
This unit appears to be a device on its own, requiring its own oil chamber and cooling chamber. Do I understand this correctly?

[mgphl52]

The MSB (aka: reverse gear) is, in fact water cooled. It is the "first" recipient of fresh water, even before the raw water pump! I have never done anything special for, but alas, KAYLA & I live in the Northwest Florida Panhandle and rarely if ever have major freezes.

[jbenagh]

I simply flush it with fresh water, about 8 gallons for the whole system, including the engine. Then put in a gallon of pink antifreeze. I do try to drain the strainer prior to each flush and fill it with the next stage fluid (fresh water then pink antifreeze).
Not that failure to have a problem is an indication of proper procedure, but it gets pretty cold here (Boston area) and I've never had an issue.
Jeff

[jmaue]

Thanks to the both of you. I removed the inlet hose from the thru hull and submerged in a 5 gallon bucket of water, then ran the engine for about 25 min. Could never get the temp as high as I wanted but am certain the thermostat had opened. Then put a gallon of winter fluid in the bucket and let it draw until I saw blue being passed out of the vessel.
As stated, the gear box sees the fresh water first in the system.
Expect it's good to go for the freeze.

[JD-MDR]

I will flush out my MD7A again soon. I wonder if the 7:1 ratio Muriatic acid and water will hurt the rubber on the impellar or the thermostat.
Also on a side note I've always wanted to comment on this engine. I think the MD7A gets a bad rap. When I bought"Leoma" The appraiser commented on the very low hours on the engine. I thought it was inaccurate that a 40 yr old engine would only have 400 hrs
But the way it runs ,maybe it's true. I have over 1000 hrs on it now and it hasn't used a single drop of oil and starts right up first revolution. I have gone thru everything except the crankcase and the cylinder head and the injector pump. I love this motor. I haven't had problems getting most maintenance parts and as long as I don't break anything I don't expect to need the discontinued parts. Also in these four years I've come across 4-5 of these engines for next to nothing. Yea it would be nice to update with a lighter more efficient engine and next time I have $30,000 to spend maybe I'll splurge, if diesel isn't outlawed

[jbenagh]

jmaue,
I try to winterize shortly after I pull into the dock at the haulout marina. In our neck of the woods I will have definitely exercised the Volvo enough to open the thermostat. Even if I don't she's fresh water cooled so clean water and antifreeze go through all the time. Getting to temp is more useful for the oil change that happens about 20 mins after the engine flush: fuel filter, bleed fuel system, coolant flush, oil change, oil fill -- did I get that right?
Jeff