Question on getting rid of air locks in coolant

wolfe10 wrote:
The answer as to whether you have an air lock depends on two primary things:

How much coolant was lost.

Whether your engine/chassis has a bleed line from the thermostat housing.

If there is any line from the thermostat housing that you can loosen and verify that there is coolant there, the risk of damage goes away (or if there is one from housing to overflow in which case it is "self-bleeding").

OK Thanks. I couldn't find a bleed line yesterday but will check again. . .

The answer as to whether you have an air lock depends on two primary things:

How much coolant was lost.

Whether your engine/chassis has a bleed line from the thermostat housing.

If there is any line from the thermostat housing that you can loosen and verify that there is coolant there, the risk of damage goes away (or if there is one from housing to overflow in which case it is "self-bleeding").

wolfe10 wrote:
There is a difference between a low coolant light (i.e. level in the reservoir is low) and low enough that there is an air lock in the thermostat housing.

If the latter, do NOT start the engine until it is addressed. Hot air will not open a thermostat and you could crack a head.

Getting rid of an air lock really depends on how the chassis is set up. Some have a bleed hose from thermostat housing to reservoir, some do not.

On our last coach, I had to loosen the coolant line that went from the thermostat housing to the air compressor to bleed out the air.

On some, it is better to remove the thermostat housing and fill SLOWLY until the coolant is right up to the thermostat level.

I suggest you check for the specifics on your chassis/engine.

I need to pick up some more coolant today and then I'll work on this tonight. What I'm not clear on is how to tell if I have an airlock or not. My plan is to fill the reservoir (which is low now) and see if it drains.

Any thought?

There is a difference between a low coolant light (i.e. level in the reservoir is low) and low enough that there is an air lock in the thermostat housing.

If the latter, do NOT start the engine until it is addressed. Hot air will not open a thermostat and you could crack a head.

Getting rid of an air lock really depends on how the chassis is set up. Some have a bleed hose from thermostat housing to reservoir, some do not.

On our last coach, I had to loosen the coolant line that went from the thermostat housing to the air compressor to bleed out the air.

On some, it is better to remove the thermostat housing and fill SLOWLY until the coolant is right up to the thermostat level.

I suggest you check for the specifics on your chassis/engine.

Twomed wrote:
196 degrees open 185 close. :)

Thanks. I need more coolant so will be trying that tonight.

196 degrees open 185 close. :)

Matt_Colie wrote:
Darryl,

I do not know the specifics of your cooling system, but there are very few that can be filled in a single thermal cycle. If the reservoir you filled is not a de-areator, then you have not filled the system. If the actual radiator has a cap, try filling it there next. it will still probably take three or more thermal cycles until it is truly full.

Matt

By thermal cycle I assume you mean run the engine until it warms up enough to open the thermostat? How hot is that?

Darryl,

I do not know the specifics of your cooling system, but there are very few that can be filled in a single thermal cycle. If the reservoir you filled is not a de-areator, then you have not filled the system. If the actual radiator has a cap, try filling it there next. it will still probably take three or more thermal cycles until it is truly full.

Matt