Purging a Cooling System

[Jon Wehrenberg]

On another thread Brian questioned the protocol for bleeding the cooling system when refilling, especially with the Webasto and all its heat exchangers.

In the past when changing my coolant I have run the engine, eventually burping the coach. That method works, but it seemed to ultimately involve 50 miles of driving before it was filled properly.

The next coolant change I used the circulating pump on the Webasto. That worked much better and even after taking the coach on the road I did not have to add any more coolant so evidently the Webasto circulating pump will purge air from the system.

But when I do my scheduled coolant change this August I am going to use this tool which I intend to buy:

http://buy1.snapon.com/catalog/item....group_ID=12500

When I change coolant this time I will likely not have any coolant in the entire system because I will also be changing hoses. I have spoken to someone who uses this tool and he swears by it. With a vacuum on the entire coolant system he states that coolant is literally sucked into every cavity and all air is purged.

[Jon Wehrenberg]

Here is another tool....Doesn't have the Snap-On name but looks to do the exact same thing.

http://www.sjdiscounttools.com/uv550500.html

[Ray Davis]

The next coolant change I used the circulating pump on the Webasto

When you say you used the circulating pump, did you just fire up the Webasto? Or did you somehow engage the pump without firing up the heater?

[Jon Wehrenberg]

I filled the system as much as possible through the big header tank. I fired up the Webasto and watched the tank level. I kept the tank filled, and was looking for the engine and the various heaters in the coach to get warm. That would indicate circulation.

Alternately I could have run the engine, but neither was was perfect because it involved a lot of playing around. I am going to use the vacuum refiller this summer.

[BrianE]

Thanks Jon. That question deserved its' own thread. What is the relationship of the driver heat circ. pump to the webasto system? Does it circulate coolant through the same plumbing? And to add to Kevin's comment, my Liberty also has the individual bleeders and I was hoping Jon could confirm I didn't need to deal with them. The access is not great.

[Jon Wehrenberg]

Yes in the case of a Webasto system. The coolant circulating through the bus air and heat the engine and the Webasto toe space heaters is one and the same. Not so with Aquahot. I don't know enough about Espar to answer.

[wrongagain]

I have to ask, what is the total gallons of water and antifreeze in the system, yes, I know they are all differant.

[Jon Wehrenberg]

A good range is 22 to 24 gallons. Different factors affect the total system volume such as the house heating system (Aquahot will differ from Webasto), and how much coolant remains in the system even after all valves have been opened.

[gmcbuffalo]

Brain I think you will have to bleed the toe kick heaters. I had one that was not working well and and its neighbor was working . I thought it was bad, but something told me to check the individual heater for air. I bleed a small amount of air out of the toekicker and presto it started putting out heat. This was with a fully filled system that hasn't been worked on for a long time. once an area is air locked I think it will need to be bleed somehow.
GregM

[Jon Wehrenberg]

I watched a Prevost tech whose name and location will not be revealed change the antifreeze on a coach. This was on a model year that had the big gate valve behind the rubber flap behind the radiator door. He closed that valve.

When I questioned him about that his response was that it traps the coolant in the heating and house systems. I later found out that it virtually eliminates any need to purge air from the system. The downside is that you can only get about 18 gallons out of the bus so some old coolant still remains in the system. I am not recommending this but passing on an observation. I will stick to doing it the hard way, mainly because I am replacing all the hosing and need it completely drained.