Running the engine with no fresh water in the system - harmful or not?

[dawntreader]

I have emptied my tanks for the winter but have found out that the water in the storage yard is not fit to drink. I therefore do not want it in my system and intend to leave the fresh water tank empty until I can refill at the marina next year. However, the trip to the marina is a 2-hour sail or motor. Question is: will it do any harm to run the engine for those 2 hours without any water in the fresh water system?

Your advice on this matter would be much appreciated   

[Salty]

Assuming you are talking about the engine fresh water system, my advice is "Don't do it."
With no water in the engine fresh water system the engine will not be cooled at all, and will overheat probably within a matter of ten minutes or so resulting in seizure and distortion, and a very large bill for engine repairs or renewal.
If you are unsure of the water where your boat is kept, then fill some containers with fresh water from home and take them to your boat in readiness for when you need to refill your cooling system.
The raw water pump will take suction from the water your boat is floating in, but it only passes that water through the heat exchanger/exhaust manifold before it is discharged into the exhaust system and then overboard. The fresh water cooling passes through a separate part of the heat exchanger where it is cooled by being in contact with, but separated from the seawater section of the heat exchanger/manifold. But if there is no water in the engine fresh water system then the rest of the engine will not be cooled, and it will overheat leading to seizure if you don't stop it fairly smartly.
I can't stress the point too much, don't do it.
If you are only worried about having no water in your drinking water tanks, that is not a problem so long as you don't get thirsty.

[MarkTheBike]

Hi Dawntreader (and Salty, of course)

If you have a look at my recent thread, http://www.bavariayacht.info/forum/index.php/topic,733.0.htm , about our recent fun and games, you will get an idea of what happens after 2-3 minutes running without coolant. We developed a crack between the heat exchanger and the exhaust manifold last Sunday (thus allowing all the coolant to drain away) and, although I was able to moor up and kill the engine in a couple of minutes, we are now faced with a minimum bill of about £2000. Leaving it running dry for longer and it's probably a new engine. As Salty says, on the assumption you are talking about the coolant, rather than drinking water, you MUST have it filled up. If there's no danger of freezing temperatures and you're draining it immediately after then use ordinary tap water but if there's any chance of a cold snap or you're leaving it in then you have to use a water/antifreeze mix. I actually use Volvo's own pre-mixed. It's not overly expensive (surprisingly) and is good quality. Bon chance...

[IslandAlchemy]

I think Dawntreader's talking about the drinking water tank.

Assuming that's what you mean, I can't see it causing any problems.  You'll be pumping how water through an empty calorifier, but I can't imagine it would do any harm.

[dawntreader]

Thanks for the responses so far but just to clarify: I am talking about the fresh [drinking] water supply only - not the engine coolant in the sealed system nor the raw sea water drawn in by the impellor. I am familiar with the dangers of the other two failing but unsure how much reliance Volvo have put on the circulation of the 'drinking' water for supplementing the overall engine cooling (if at all).

[MarkTheBike]

Aha! Actually re-reading it all, looks like I jumped to a wrong conclusion. My apologies, Dawntreader. Does your calorifier have an isolator tap on the hot feed? If so then I would have thought just keeping it shut should do the trick.

[Murphy]

In the summer we ran out of fresh water and had to run the engine for over an hour on an empty tank to get into the marina prior to filling the water tank back up. No damage occurred to any of the systems, they are still all working fine.

[Lazy Pelican]

When we bought our first Bav in 2004 we were specially warned not to run the engine with the calorifier empty. Unless you've run the hot taps there will still be water in the calorifier, regardless of the tank status.
If the calorifier is empty isolate before running the engine.

John

[dawntreader]

Thanks for all the replies. I will take a 'safe' option and use jerrycans to partially fill the tank (and calorifier) just before we relaunch. Also, a good way to use Christmas calories by hauling the water up top 

[tiger79]

You don't need to add water, no damage can occur.