Anti Freeze, and Closed cooling system.

[tommyt]

Tony,

My yard guy says that I worry too much. It is normal to have pressure in the system. Let's start her up and see what happens! There may be a leak from the over flow to the engine, but if there is no coolant other than what came out when you opened the radiator ( there was none, I had already checked) then it probably just drained back because it could.

Now, this all sounds great. However, if STUFF happens, his balance increases and mine decreases. Bottom line, I don't think there is a problem. I have never found a leak even though I think there must be one.

Let you know some time next week. Hopefully it gets to the 50's for the splash.

[Craig Illman]

When I had some disappearing coolant in the engine, I rented a radiator pressure tester from the local tool rental outlet. Confirming my suspicions, I had a failed heat exchanger. Later, when I was loosing coolant from the overflow tank and finding it under the engine, I thought it was the hose/clamps and replaced them. It turned out to be leaking from the cap.

I agree with Ron, it's going somewhere! The bottom line is that the engine needs an adequate level of coolant. You can either periodically top it off or chase the leak.

Craig

[tonywright]

I'm thinking maybe radiator cap. The coolant is full under the cap. I wonder whether the super cold temperatures do something to the pressure under the cap, forcing the cap open, and allowing the coolant to leak out all the way from the overflow tank. (since it is higher than the cap).  Once the temperature rises, the cap seals again, and so the reservoir is still full when we open the cap in the spring. Is this crazy?  Could it be due to the coolant not being mixed strong enough for the colder temperature in Canada? (Down to -25 or -30 celsius).

I did see a drop or two of coolant under the engine. The rest probably disappeared into a location in the bilge that will not drain into the main bilge until the boat is back into the water, since the boat is tilted aft on the hard.

Maybe nothing will happen once the boat is in the water. But then my plan then would be to drain the coolant, add a stronger mixture, and replace the cap.

Thoughts?

Tony

[foursailing]

Noticed this weekend that there was a small crack in the plastic overflow reservoir - right in the groove where the metal band / wire attaches the unit to the inside of the locker.  It was a very slow leak, but as soon as I removed the metal wire, the leak was quite noticeable - worth a check

[Stu Jackson]

Bill's point is well taken.  This is not some supernatural occurrence or voodoo or magic.  If the liquid is disappearing, it IS going somewhere.  The linked reference earlier in this thread dealt with possibilities:  hose clamps, hoses, leaky HX, connection to hot water heater, etc.  If it was my boat, I'd make a thorough list of each one, and then I'd carefully check each and every one of them and not believe some boat "mechanic" who says I worry too much.  It's my boat, and my safety, not his, out there.

[Jack Hutteball]

I too had a similar problem.  Took a while to find the problem, which turned out to be hose clamps, a number of them throughout the system.  the major leaks were the hot water tank connection, and a splice that was made for the heater when the boat was commissioned.  All of them dripped just enough to drain the expansion tank, but not enough to easily show up.

Jack

[tommyt]

Stu, I think that you may have read my reply a little to literally. He did say I worry too much. This yard has done work on my, and many other boats, for quite some time. They did not see any big issues, there was pressure and therefore coolant in the tank, and until we started it up we would not know if and where a leak was because there was little evidence of coolant in the bilge or otherwise.

Splashed the boat today, started the engine, and as it warmed the overflow tank filled back up. Not completely full, but about where it would allowing for the coolant that came out when I opened the radiator cap. We ran it for over an hour and found no new leaks. They believe that I should replace the cap as the seal might be bad as the weather cools or the spring could be bad....both of which could allow the overflow tank to drain back into the radiator as the temperatures get below zero and the coolant condenses.

Is that the end...is it ever? Of course I will continue to be vigilent and see what happens with the system. I will change the cap. I will make sure it is topped off. If it goes down it has a leak. We will see.

Tony, I hope yours is similar to mine. Good Luck.

Now wet and cold in northern Michigan

[Ron Hill]

Tomm : Sounds that all is OK.  Keep your hands off of the coolant cap and check the level by examining the reservoir level.  Every time you open the cap - you screw the coolant recovery system up.  Good Luck!!

[tommyt]

Ron,

You are going to have to explain how I replace the cap without taking the old one off. Am I missing something?

[tonywright]

Thanks for the update Tom. Sounds as though I should take some of the coolant out that I added to the reservoir already. Otherwise it could overflow if it fills back up like yours did.

I have been thinking about the hose leak theory some more. Here's the question: if the hose clamps are leaking, how come the tank is full under the cap? A theory has to explain all the facts...

4 days and counting.

[tommyt]

Tony,

Remember, that like me, you must have pulled the radiator cap to see that it was full and under pressure. In doing so I lost some coolant. When my engine heats up the coolant only comes back to the add mark, not the full mark.  Somewhere in between is proably safe.

Tom

[tonywright]

Launched Saturday, and engine started first attempt. No sign of any issues at all.  I had reduced the overflow tank to the add mark. Has not moved from there. No sign of any antifreeze in the bilge, or anything else.  If I discover anything new, I will post. Right now we are still busy doing spring commissioning. The tanks still have antifreeze in them, and the water heater is still drained.

Tony 

[Ron Hill]

Tomm : Sorry, I didn't see your question. 
Replace the cap and then let Physics do the rest. 
As the engine heats the air/coolant expands and goes into the reservoir.  When the engine cools the vacuum created inside the engine reservoir will suck the coolant it needs back in.  It will take a few of these cycles to stabilize the outside coolant reservoir and get all of the air out of the system. 
I remove my cap when I need to bleed the internal system ie. changing the exhaust riser, changing coolant hoses or changing the coolant every 4/5 years. 
Otherwise I check the coolant level by looking at the reservoir and NEVER take off the cap just to see if it's full !!!