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Old 17-08-2012, 22:32   #1
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At what temperature should my MD2B be running ?

My Volva MD2B quit on my the other day. It restarted right away but I let it cool for about 30 minutes before really using it again (to get back to dock). The prop was a bit fouled by crusty growth ( could that extra load cause a heating issue ?).

Now that I've been searching around for typical operating temperatures for this engine I'm a little bit alarmed because a lot of them see very low in comparison.

I've been running this engine for a couple of years now and the typical water temperature on my gauge is around 190F, sometimes going right up to the 212 mark. I recently bought an infrared gauge to see what other parts of the engine were up to. some parts around the cyclinder were up to about 220 F, while the thermostat cap rarely goes over 100 F.

Have I been slowing killing my engine with heat ? It's been very rock solid and has been run in this condition for up to 8 hours at a time with no apparent problems.

Any thoughts ?
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Old 18-08-2012, 00:34   #2
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Re: At what temperature should my MD2B be running ?

Salt precipitates out of seawater forming a rocklike accretion on the internals of the engine. Not sure what the temperature is but definitely below 160 degrees, with 140 degrees being a good temperature to run the engine. My MD2B ran so cold it wouldn't heat water in the heat exhcanger hot water tank.

You may have a buildup of this salt accretion in your engine. The temps you are reading would be an indication of blocked or severely restricted passages. I don't know if it's possible to get rid of these deposits once they occur. Seems there would be some chemical that would eat the stuff though. There is a product called SaltAway that the local fisherman swear by to keep their outboards running.
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Old 18-08-2012, 10:05   #3
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Re: At what temperature should my MD2B be running ?

My md2b ran alot hotter before i removed the exhaust manifold, cleaned it all out of all deposits and replaced the rubber hosing. I also cleaned up the head water chambers as best i could. I also replaced one of the heads, so its water passages was thoroughly cleaned.
My engine now will not register a temperature on the gauge. And when i place my hand on the cylinders after running they are barely warm.
I think that just a manifold off the engine thorough cleaning would always give a big benefit to keeping hte engine running cooler.

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Old 18-08-2012, 10:23   #4
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Re: At what temperature should my MD2B be running ?

Assuming you are raw water cooled.... mine ran very cold... like 160 degrees or less.... something wrong if you're running that hot.
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Old 18-08-2012, 13:51   #5
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Re: At what temperature should my MD2B be running ?

Your engine is running hotter than it should, normal operation would be under 80 degrees C. Clean the exhaust passage water ways (a mechanical task) and check all hoses for build up of deposits. The thermostat housing generally has the thermostat bypass running over it so it stays cool even with the thermostat in the closed position. Check the housing and thermostat for deposits and clean out.

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Old 18-08-2012, 19:33   #6
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Re: At what temperature should my MD2B be running ?

There is a passage in the manual where it says how to test the thermostat. Test yours and you will know if it kicks in right. Remember your gauge MAY be off. If the Thermostat is fine then you most likely run your engine fine. Unless alarm lamps/sounds tell you otherwise.

If your prop was seriously fouled then power loss is obvious and you may too see the engine stop the moment you go in gear - especially if your idling revs are set very low.

Otherwise suspect some other issue like fuel line blocked or similar.

Cheers,
b. (MD7A)
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Old 18-08-2012, 19:45   #7
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Re: At what temperature should my MD2B be running ?

That's hot. Can't remember the thermostat temperature, but well less than that in the raw water cooled version. As you run hotter stuff precipitates out even faster, making a vicious circle.

Haven't tried this yet myself, but giving it some thought.

Barnacle Buster

There are a number of other similar products, gets further into many channels than physical can.
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Old 24-10-2012, 08:27   #8
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Re: At what temperature should my MD2B be running ?

Quote:
Originally Posted by Acushla View Post
Your engine is running hotter than it should, normal operation would be under 80 degrees C. Clean the exhaust passage water ways (a mechanical task) and check all hoses for build up of deposits. The thermostat housing generally has the thermostat bypass running over it so it stays cool even with the thermostat in the closed position. Check the housing and thermostat for deposits and clean out.

Acushla
on my boat I spend the same tato defective thermoses volvo2d75
repair after you install the following device


Alarma temperatura motor programable embarcacin - NAUTICA SEYMO
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