Valve on the cooling line, what is it?

[Dima]

I have something looking as a valve on the cooling line on the top of the engine on the hose going from the engine to the water heater. I found somewhere mentioned that there should be "bleeding valve?". What it is for and how it works? Looks like it opens when you turning it clockwise (?). I'm asking because I changed water heater and getting overheat alarm now. I thing I have an air somewhere, but not sure how to fix this. I'm going to flush cooling line and replace antifreeze, but I need help to understand this valve and a way to blow out potential air pockets.

The boat is 1991 Hunter Legend 35.5, engine is Yanmar 3GM30F.

 

[justsomeguy]

Sounds like a bleeder valve to me. When pressurized, try opening it slightly to allow trapped air to escape, and when it spits coolant, close it.

 

[Dima]

Thank you, justsomeguy! Just to be sure: it should be normally closed, right? In my case, turned counter-clockwise, right? Than, when engine is running and get to proper temperature, open it a little (turn clockwise) till it starts spit antifreeze.

 

[justsomeguy]

Thank you, justsomeguy! Just to be sure: it should be normally closed, right? In my case, turned counter-clockwise, right? Than, when engine is running and get to proper temperature, open it a little (turn clockwise) till it starts spit antifreeze.

Correct, normally closed. You're very welcome.

 

[Stu Jackson]

If you do a search on "Burping" - your engine, that is , on this board, you'll find many discussions and links. The issue is an air "bubble" in the line from the engine to the water heater and back to the engine. You need to get rid of the air pocket to avoid overheating. There are a few different ways to do this. Good luck.

 

[Dima]

Did search here and didn't found anything for "Burping"... However, google show nice article here: http://forum.woodenboat.com/showthread.php?113589-Yanmar-engine-overheat-problem

Thanks a lot to everybody!

 

[Stu Jackson]

Try this:

Engine Overheating 101 - How to Burp Your Engine (Reply #6) http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462

 

[sailaway78]

Turn clockwise

If you have a valve that you have to turn clockwise for off, you have a gate valve. That has absolutely no place on a boat. Get it out of there. Replace it with a ball valve, and you will be much better off.

 

[Dima]

I'll make a picture tomorrow. I don't think previous owner had something wrong installed, he is very serious sailor. May be it is my English - it is not turning, it is screwing (?), spinning a handle probably dozen circles. I think picture will explain better

 

[tkanzler]

Does it look like this?

 

[Dima]

Yes, it looks similar, thank you!

 

[tkanzler]

That's an old-school radiator drain valve, probably used for burping the water heater line, as has pretty much been established.

 

[Ron20324]

Did you burp the water heater?