Anti Freeze, and Closed cooling system.

[tommyt]

C34MKII, 2004

Checked the boat in preparation for splash in a couple of weeks. When put away for the winter engine systems were all in great shape, oil and transmission fluids all fresh, etc. Coolant was at proper level after checking both engine and overflow tank.

When checking levels this week I find the overflow tank empty which surprised me. More surprising was when I pulled the radiator cap off and had pressure in a cold cooling system. Enough that coolant would come out if I did not replace the radiator cap.

Thoughts??

[Ron Hill]

 Tom : Hmmm !!  The WX could have changed enough to cause the coolant to flow out of the internal tank when the cap was opened.  However, I don't believe that the WX change would have emptied a full reserve reservoir.   I'd look for a leak in that coolant recovery line. 

[tommyt]

Ron,

Thanks for the response. I have checked most of the line and cannot find anyplace where it looks to be leaking. The resovoir is in the lazarette and I have traced it back.

But, how would you explain the pressure behind the radiator cap. I could understand some pressure with a hot engine, but a layed up engine. When I removed the cap I had flow that only stopped when I put the cap back on.

Thanks,

Tom

[Jon Schneider]

Is it possible that when you checked the coolant level in the overflow tank last year, you did it after the engine had been warmed up?  In that case, you were seeing the "normal" low level actually when it should have been high.  As to the pressure, all I can think of is that you've got a blockage in the overflow tube or the coolant cap on the engine is broken (frozen closed).  Just guesses.

[Stu Jackson]

Check the connection to the hot water heater, too.  See: http://c34.org/bbs/index.php/topic,3769.0.html

[tonywright]

I found exactly the same on mine this weekend.  Coolant full under the "radiator" cap, and reservoir empty.  Have plannned to call the mechanic to see if we can find any problem.

Tony

[tommyt]

Tony, I am also contacting my guy, but they are so busy dropping boats in the water right now, it may take a few days for them to look at it. With the current temp at 35 degrees F, you have to wonder why.


Just a thought, and this may be out in left field. Is it possible that the overflow tank flowed back into the radiator as temperatures dropped over the winter, as it is designed to do, and now that anti freeze has expanded and needs to be heated to open the radiator cap and let it flow back up to the overflow tank.  This may be way out of line, but I have never checked the levels with the temp in the 30's before, and therefore am trying to figure it out.

[tonywright]

Tom

I am hoping that it is exactly that, and nothing else. Last year when I brought the boat up for the winter the system had never been properly bled, so there was no real connection between the overflow tank and the engine, and hence no drop over the winter. I opened the bleed valve once the engine was warmed up last year, and vented the air, and it suck a fair amount of additional antifreeze from the overflow tank. So this was its first winter where the coolant was at a proper level in the engine. Here the temperature drops below zero Fahrenheit in the winter, so if the coolant shrinks it will shrink a lot!

Once my mechanic has had a look, I will let you know what he says.

Tony

[tommyt]

Tony,

Although they have not looked at it yet, the yard says they do not think it should be a problem. Hopefully will know before they splash her on Monday.

Tom

[tonywright]

Tom

My mechanic could not find anything wrong today. He reckons to run the engine after we are in the water and then we might see something, or most likely not. I sure would like to know what caused it though, and where all that antifreeze went!

We tightened the alternator belt today. I had noticed some squealing at high RPM last year, which I thought was coming from the dripless stuffing box. The rep at the baot show said not possible: it's your alternator belt. Didn't seem slack, but we could tighten it a bit, so we'll see.

Tony

[Ron Hill]

The idea behind a coolant recovery system is that you don't have to open the cap to check your coolant level.  All you do is look at the coolant level in the recovery bottle.
Even with a cold engine - if you open the cap you will get some overflow of coolant.  

[tonywright]

Hi Ron

That's exactly what my PO did. He didn't realize that he had an airlock preventing the flow of coolant from the tank. When I opened the cap, the collant was a couiple of inches below the cap. I bled the system, which then made proper connection with the overflow tank. Moral of the story: check under the cap from time to time.

Tom and I both separately discovered the overflow tank was empty this spring, so opened the cap to see whether all the coolant had drained out. It hadn't. The system was full. So where did the coolant from the tank go? This is still the mystery. 

Thanks

Tony

[Stu Jackson]

How do you get an airlock in what is essentially an open tube between the reservoir and the manifold?

[Momentum M]

Guys, we've had numerous discusions on the subjet and I'm posting the link to one discussion.

At that time I tough that the problem had solved itself but I've notice that no matter what...that overflow bottle wants to stay empty.

Like mentioned, I've refilled to the mark quite a few times and one of those mystery of boating...it always disaper and I still don't know where!!!
There is no sign of leaks and the bilge is dry and no sign of the green stuff.
My motor is still fairly new so I doubt that it's going through the lining or else.

So from now on...I check now and then the level under the cap (it's always to the rim) and keep an eye on the gage when motoring.


http://c34.org/bbs/index.php/topic,2947.0.html

[Ron Hill]

Guys : I'd keep an eye on the coolant recovery reservoir.  That coolant is going somewhere!! - if not a hose to the water heater, maybe an internal leak in the heat exchanger???