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Refilling engine coolant

HeavyOp

Member
Joined
May 18, 2012
Messages
10
Location
Halifax, Nova Scotia, Canada
I don't understand refilling engine coolant. Do you refill it in the overflow tank that gives a reading? Or is there another main engine coolant tank that you fill? Or is the overflow tank what you use? I don't get how that works exactly. Does the overflow tank fill and empty itself from the main tank depending on how full the main coolant tank is?
 

joispoi

Senior Member
Joined
Mar 1, 2008
Messages
1,284
Location
Connecticut
Fill the overflow tank. If you've emptied the system for service, refill the system at the radiator (do not open it when it's hot) then fill the overflow tank to the mark.
 

Bala

Well-Known Member
Joined
Mar 19, 2011
Messages
191
Location
Qld Australia
I don't get how that works exactly. Does the overflow tank fill and empty itself from the main tank depending on how full the main coolant tank is?

Yes it is a recovery tank, as said above you need to make sure the coolant level is full in the radiator " Dont open when hot". Then add the correct amount in the overflow bottle. Make sure the radiator has the correct cap on it. The radiator cap will allow coolant to be pushed out in the overflow bottle as it expands in the radiator and also drawn back in as it cools down OR LEAKS> If you need to keep topping up the over flow bottle this is quite possibly telling you that you have a coolant leak.
 

HeavyOp

Member
Joined
May 18, 2012
Messages
10
Location
Halifax, Nova Scotia, Canada
So I don't get a reading from the radiator right? I only open the radiator cap if it's been emptied for service and fill it then?

I only get a coolant reading from the overflow tank? Do i judge the reading when the engine is cold or hot? Cold I assume?
 

HeavyOp

Member
Joined
May 18, 2012
Messages
10
Location
Halifax, Nova Scotia, Canada
The coolant bottle in the machine storage compartment is all that needs to be used to refill the overflow tank? Don't you have to sometimes mix in water or is that already usually done in that bottle? Sorry for all the detailed possibly dumb questions
 

willie59

Administrator
Joined
Dec 21, 2008
Messages
13,361
Location
Knoxville TN
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Service Manager
Radiators and coolant recovery tanks. It's actually quite simple HeavyOp, when things are hot they expand, when they're cold, they contract, this includes engine coolant. In the old days, radiators had large reservoirs on them, generally on the top of radiator. One would fill these radiators to no more than 1" from filler neck in top of radiator with engine/coolant cold. When engine/coolant warmed up, the coolant would expand and take up that 1" of air space in top of radiator reservoir, no coolant recovery bottle was used or needed.

Coolant recovery bottles came to use in automotive when the nose of cars got smaller, no room for bulky radiators with large tanks. This also when they moved the radiator reservoir from top of radiator to sides, again, to make radiator less tall. These more compact radiators left no extra room for an air space for expansion of coolant when warm, therefore, recovery bottle was incorporated. With this type of cooling system, radiator is filled completely with coolant with engine cold, recovery type radiator cap is fitted, then you fill the recovery bottle to the "COLD" mark on recovery bottle. As engine/coolant warms up, coolant expands, is forced through recovery cap, and goes to recovery bottle. When engine is shut down and cools off, coolant in system contracts and draws coolant back into system from recovery bottle. ;)
 

Bala

Well-Known Member
Joined
Mar 19, 2011
Messages
191
Location
Qld Australia
The coolant bottle in the machine storage compartment is all that needs to be used to refill the overflow tank? Don't you have to sometimes mix in water or is that already usually done in that bottle? Sorry for all the detailed possibly dumb questions

Ok, you have the overflow tank connected to the radiator, it now sounds like you have a bottle of coolant on the machine and are asking of you just top up with that or mix with water??

There are many different options for cooling systems and the coolant that is run in them, some have cartridges that get changed like a filter, some you mix with water, some run a straight from the bottle mix, you can get test strips to test the coolant etc, very important to know what is in you unit and that it is correct and not to mix different types.
 

toomanymachines

Well-Known Member
Joined
Feb 2, 2011
Messages
69
Location
mb
Pure ethylene glycol needs to be mixed 50% with water. Some come premixed. pure stuff is rather viscus, and you can tell it is pure by the thickness of it. If you run pure in our cold climate, it will gel at -40. That will plug your rad and overheat the machine. You can always test the antifreeze with a tester, I prefer the prism type. Look for at least minus 35. ( well at least where I live)
 
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