MD6 thermostat

Oct 30, 2019
62
Motored 5 long hours yesterday. That's 25 miles plus or minus,
compared to 700 miles motoring (more or less) coming home from
Mexico. . .I think I must have built up a bit of an allergy to
motoring, though I didn't come down with the hives or sneezes or
anything. . .just spent the day remembering how much I like sailing.
Anyway, I noted again that the thermostat must be sticking closed on
the MD6. Every now and again she would come off the steady running
temperature (around 50C ) and bump up over boiling for a second or
two (100 to 120 C) and then cool back down to 40C. Very nerve
wracking and presumably hard on the cast iron. So I'll shortly
undertake to correct the problem. Any and all (good) advice
cheerfully accepted. Please someone start by commenting on the
location of the thermostat. A quick glance didn't convince me I knew
where to look. Thanks, Ken Preston, Seattle area.

PS--ordered the letters for her new name. It won't fit on the
transom with all the other stuff (wind vane, exhaust hose etc) so
I'll put it on the stbd quarter. I keep hearing I must do something
about a renaming ceremony. H'mm. Just scraping off the old letters
isn't sufficient?
 
Oct 30, 2019
77
Your engine is probably heating up just because you are thinking of
renaming without the ceremony! Don't risk it!

Come to think of it...maybe my boat was re-named without a ceremony
at some point. Maybe thats why my stern gland is leaking.

RE location of the Thermostat. Which engine do you have. if its an
MD6a I'm sure someone here will be able to tell ya. I don't have my
manual with me (at work) or I could.

Do you have the Manual? I could Photo copy one and send it to you
if you give me an address. I also have a repair manual (sort of
like a shop manual for cars, it's not real extensive but it's
helpful.) I could find that section and send that as well.

Note: My Temp Guage isn't working so I don't have to be bothered
with such concerns.
 
Nov 8, 2001
1,818
Hi Ken

The thermostat is at the end of the heat exchanger/exhaust manifold on the starboard side. If heat problems then you can always take the thermostat out totally. It engine will not get to full temperature but at least you will not boil the engine. Might be an idea to take the exhaust manifold off and clean all the cooling waterways, this is a common problem and is the usual cause of overheating MD6/7 engines.

Is it still ok to serialise your article in the VAGB newsletter over the next three or four? You will off course be sent the NEwsletter free of charge.

Great way to rename the boat is buy a case of good red wine, good friends, many glasses and celebrate. When the wine has gone I am sure you will have renamed your Vega.

Hope all goes well.

Steve Birch Vega "Southern Comfort" V1703
 
Jan 28, 2001
694
Hi Ken, About the re-naming. You're supposed to run aground first. If you
change the name without doing so it's supposed to be bad luck. I think just
touching the bottom with the keel is good enough.
If you haven't done so yet you can have one mine. I had numerous meetings
with the mud in San Francisco bay. What's the new name going to be?
Walt, Lyric