Draining/Replacing Coolant - are these 2 things normal?
99 Jeep Cherokee Sport, 4.0
My leaking radiator had to be replaced, so I drained the coolant. About a half gallon drained out through the drain hole. A little more drained when I removed the hoses, but not much. Is that normal? I was expecting alot more to drain out. Is there something else I should do to get all the coolant out of the system? Or does the small amount that drained out indicate a problem somewhere?
I used an to refill and bleed out the air. With the engine running all was good, air was bubbling out with a few inches of coolant in the funnel. Then the coolant in the funnel backed up and overflowed while doing some serious bubbling. Why would the coolant backup? Might there be something wrong with the water pump? Or is this normal for bleeding a system that has lots of air in it?
I shut off the engine and called it a day. I'll try again after I know what's going on. Thanks.
My leaking radiator had to be replaced, so I drained the coolant. About a half gallon drained out through the drain hole. A little more drained when I removed the hoses, but not much. Is that normal? I was expecting alot more to drain out. Is there something else I should do to get all the coolant out of the system? Or does the small amount that drained out indicate a problem somewhere?
I used an to refill and bleed out the air. With the engine running all was good, air was bubbling out with a few inches of coolant in the funnel. Then the coolant in the funnel backed up and overflowed while doing some serious bubbling. Why would the coolant backup? Might there be something wrong with the water pump? Or is this normal for bleeding a system that has lots of air in it?
I shut off the engine and called it a day. I'll try again after I know what's going on. Thanks.
Last edited by Cameron58; Oct 5, 2019 at 09:51 PM.
Senior Member

Joined: Jul 2012
Posts: 794
Likes: 104
From: Aldie, VA
Year: 1999
Model: Cherokee
Engine: 4.0
I typically take off the heater hoses connected to the thermostat housing and use a nozzle to push air from my compressor through the hose. I just cup my hand around the nozzle and get a lot of coolant out of the bottom hose. When refilling, I leave the radiator cap off and squeeze the top hose and refill until I don't get anymore bubbles. Then I run it for a few minutes without the cap on until I see it start to expand and put the cap back on. I repeat the next day after it's cooled off and then I call it done.
The coolant will expand quickly as the engine heat up. Then the thermostat opens and it starts flowing through the block. If it was backing up into the funnel, you were probably getting up in temp. You can't cheat physics. PV=nRT. As temp goes up, pressure and volume go up. If pressure is not contained, the volume will keep going up.
The coolant will expand quickly as the engine heat up. Then the thermostat opens and it starts flowing through the block. If it was backing up into the funnel, you were probably getting up in temp. You can't cheat physics. PV=nRT. As temp goes up, pressure and volume go up. If pressure is not contained, the volume will keep going up.
Every other year I dump my coolant in my '00. Do it by dropping the lower radiator hose.
About 2 gallons come out.
I use a funnel like yours. Using my Ext Idle switch, runs the Jeep at 1000 RPM, I let it run for about 1/2
to 45 minutes with the heater on with the blower on high.
Always making sure that there is some coolant in the funnel. You never let it run dry.
At that point in time I am good to go.
It has never backed upped on me like you describe.
Did you have your heater on?
About 2 gallons come out.
I use a funnel like yours. Using my Ext Idle switch, runs the Jeep at 1000 RPM, I let it run for about 1/2
to 45 minutes with the heater on with the blower on high.
Always making sure that there is some coolant in the funnel. You never let it run dry.
At that point in time I am good to go.
It has never backed upped on me like you describe.
Did you have your heater on?
Senior Member
Joined: Sep 2018
Posts: 802
Likes: 140
From: NJ
Year: 1992
Model: Cherokee (XJ)
Engine: 4.0
It depends how you were taught or when you grew up. I always run the heater when burping a cooling system even though some do have coolant flowing through them constantly. That's the way I was taught by my dad and my grandfather.
I always figured, it couldn't hurt.
I always figured, it couldn't hurt.
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Changing anti-freeze, turn oun heater, and do what you have to do.
It is just automatic pilot. I don't even think about it.
Here is the sad part. Even with this being brought to my attention I guarantee next April when I swap out my
anti-freeze I will turn on the heater. And after about 5 minutes all these posts about this will come back to me.
LOL
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