Purging air from cooling systeim

[Jeff]

I asked this question once before and the only answer I got was read the
manual. Nothing in the manual says how to purge the air when changing the
coolant. It says add coolant slowly. Is there another way to know you
don't have any air pockets in the cooling system after changing the coolant.
I have an 02 Outback. Thanks Jeff

 

[Kurt C. Hack]

Yeah, you don't blow head gaskets...

Just kidding, I usually run the vehicle with the rad cap off for a few
minutes and watch for the level to drop. If it drops then you know an
air bubble just escaped. After it sits level for a few solid minutes,
you have them all out. It doesn't hurt to elevate the front of the
vehicle to make sure the rad cap is the highest point of exit either.


-Kurt

 

[John A. Mason]

I asked this question once before and the only answer I got was read the

manual. Nothing in the manual says how to purge the air when changing the
coolant. It says add coolant slowly. Is there another way to know you
don't have any air pockets in the cooling system after changing the
coolant. I have an 02 Outback. Thanks Jeff

Actually, this topic is discussed often on the group. Make sure the radiator
vent valve is removed while adding the coolant (this valve is a small one
located at the upper left part of the radiator when facing the engine). Also
add coolant very slowly. I also like to bounce the car up and down to help
'jiggle' the water/air. In some cases, running the engine and removing the
water heater hose going to the firewall can help. I'm sure there are other
methods used as well.
John

 

[Jeff]

Thanks actually I looked for the valve before but couldn't find it. Jeff

 

[Edward Hayes]

My 2000 Forester W 2.5L engine doesn't have a bleed valve. I thought
it was only on the turbo models. I just fill radiator full and with
cap off run the engine until it burps and top hose is hot and coolant
is moving. I keep running and add fluid for say 5 minutes. I let
engine cool down, top up radiator, add to coolant bottle and put
radiator cap back on. The next time I drive and let engine get cold I
recheck the overflow bottle and top up if needed. Never had a problem
doing it this way.

 

[Jeff]

Thanks

My 2000 Forester W 2.5L engine doesn't have a bleed valve. I thought it
was only on the turbo models. I just fill radiator full and with cap off
run the engine until it burps and top hose is hot and coolant is moving. I
keep running and add fluid for say 5 minutes. I let engine cool down, top
up radiator, add to coolant bottle and put radiator cap back on. The next
time I drive and let engine get cold I recheck the overflow bottle and top
up if needed. Never had a problem doing it this way.

 

[John A. Mason]

My 2000 Forester W 2.5L engine doesn't have a bleed valve. I thought it

was only on the turbo models. I just fill radiator full and with cap off
run the engine until it burps and top hose is hot and coolant is moving. I
keep running and add fluid for say 5 minutes. I let engine cool down, top
up radiator, add to coolant bottle and put radiator cap back on. The next
time I drive and let engine get cold I recheck the overflow bottle and top
up if needed. Never had a problem doing it this way.

My '90 Legacy has the vent valve as does my '02 Outback VDC Sedan.
I agree with burping the engine, as much as possible.
I don't trust using the overflow bottle at all. I don't know why... just
seems better to check the actually radiator level, at least for me.
You cannot be too careful in taking your time when refilling the cooling
system in a horizontal engine design.
John