Somone explain the coolant flow please.
Thread Starter
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Junior User
Joined: Jun 2006
Posts: 90
Likes: 1
Somone explain the coolant flow please.
Ok so I replaced the leaking intake manifold on the 02 Expedition and its still overheating, and still no interior heat.
When facing the truck, if you grab the right hose that goes to the heater core, the one thats directly fed off the intake manifold its hot, however the hose to the left of this one is not hot, and the hose can easily be squeezed. I suspect that I have some type of blockage in the heater core, causing flow/ air lock issue in my cooling system.
Before I rip the dash apart, I am going to eliminate the flow to the heater core and create the loop under the motor bay.
Can someone confirm for me which side feeds the heater core and which side returns to the block. ?
I also checked the lines feeding into the rear heater core and they were ice cold.
Not sure if the metal tubing that runs under the intake manifold is the feed or the return.
Thanks!
When facing the truck, if you grab the right hose that goes to the heater core, the one thats directly fed off the intake manifold its hot, however the hose to the left of this one is not hot, and the hose can easily be squeezed. I suspect that I have some type of blockage in the heater core, causing flow/ air lock issue in my cooling system.
Before I rip the dash apart, I am going to eliminate the flow to the heater core and create the loop under the motor bay.
Can someone confirm for me which side feeds the heater core and which side returns to the block. ?
I also checked the lines feeding into the rear heater core and they were ice cold.
Not sure if the metal tubing that runs under the intake manifold is the feed or the return.
Thanks!
Junior User
Joined: Aug 2010
Posts: 76
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From: Maryville
Sounds like your suspicion is right on however I would flush out the heater core before cutting the hoses and joining them together to bypass the heater core.
The hose that was hot goes from the engine to the core the hose that was cold goes from the heater core to the engine.
You can flush the heater core out with a garden hose and a spray nozzle. Anything more than that and you can rupture the core. Take both hoses loose and alternate spraying water through both sides. You should be able to tell a difference in water flow win the blockage breaks loose. If you have rear heat as well you will probably have to flush the rear core out along with the lines that go from the engine to the rear core. If that doesn't work it means time to pull the dash.
Good luck man.
The hose that was hot goes from the engine to the core the hose that was cold goes from the heater core to the engine.
You can flush the heater core out with a garden hose and a spray nozzle. Anything more than that and you can rupture the core. Take both hoses loose and alternate spraying water through both sides. You should be able to tell a difference in water flow win the blockage breaks loose. If you have rear heat as well you will probably have to flush the rear core out along with the lines that go from the engine to the rear core. If that doesn't work it means time to pull the dash.
Good luck man.
Senior User
Joined: Jan 2008
Posts: 420
Likes: 0
From: New Hampshire
Ok so I replaced the leaking intake manifold on the 02 Expedition and its still overheating, and still no interior heat.
When facing the truck, if you grab the right hose that goes to the heater core, the one thats directly fed off the intake manifold its hot, however the hose to the left of this one is not hot, and the hose can easily be squeezed. I suspect that I have some type of blockage in the heater core, causing flow/ air lock issue in my cooling system.
Before I rip the dash apart, I am going to eliminate the flow to the heater core and create the loop under the motor bay.
Can someone confirm for me which side feeds the heater core and which side returns to the block. ?
I also checked the lines feeding into the rear heater core and they were ice cold.
Not sure if the metal tubing that runs under the intake manifold is the feed or the return.
Thanks!
When facing the truck, if you grab the right hose that goes to the heater core, the one thats directly fed off the intake manifold its hot, however the hose to the left of this one is not hot, and the hose can easily be squeezed. I suspect that I have some type of blockage in the heater core, causing flow/ air lock issue in my cooling system.
Before I rip the dash apart, I am going to eliminate the flow to the heater core and create the loop under the motor bay.
Can someone confirm for me which side feeds the heater core and which side returns to the block. ?
I also checked the lines feeding into the rear heater core and they were ice cold.
Not sure if the metal tubing that runs under the intake manifold is the feed or the return.
Thanks!
Fleet Owner
Joined: Apr 2008
Posts: 24,324
Likes: 5,136
From: 0,0,1
When flushing, start by running water into the side that had the cold hose. This way you're back flushing the core and not forcing the blockage in further.
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Junior User
Joined: Jun 2006
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Well I took your advice and unhooked flushed the front and rear heater core, the front had terrible flow and finally it cleared up. The coolant in this truck looked like rust from both units. I waited until it ran clear from both units. Hooked it all back up, and no overheating and I drove for a good 20 minutes. I also have heat again.
The needle still rides higher then halfway on the temp gauge but I am hoping once I get all the air out, it will be ok.
On the interstate the temp guage drops to right at half or below.
Yay!
The needle still rides higher then halfway on the temp gauge but I am hoping once I get all the air out, it will be ok.
On the interstate the temp guage drops to right at half or below.
Yay!
Junior User
Joined: Aug 2010
Posts: 76
Likes: 0
From: Maryville
Good deal man. I had the same problem with mine when I first got it. Did the flush and replaced the thermostat. Some people will never service their coolant system, and you end up with this kind of problem.
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Junior User
Joined: Jun 2006
Posts: 90
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Oh no! It overheated on me again! I am stumped, Intake Manifold has been replaced as it was cracked and leaking, overflow tank replaced, thermostat replaced, and system flushed. Only thing not flushed is the radiator....the truck overheats and then limps into the safe mode. No coolant smell in the exhaust, and the shop said didn't detect gas/exhaust fumes in the coolant. Bled the air from the system.
I noticed one thing, I see a small leak in the bottom of my radiator now...ok not huge but enough to drop about 2 cup fulls of fluid. So I need to replace the radiator without a doubt at this point.
I have the radiator cover off the top and even when the truck is overheating Only the passenger side of the radiator is hot, I can touch my hand all the way across the top of the radiator, and almost 40% down the radiator before it gets hot.
I am hoping at this point that the radiator just has bad flow and thats causing the overheating issue at this point. The lower hose just seems way to cool if the water really is boiling like it says it is.
I noticed one thing, I see a small leak in the bottom of my radiator now...ok not huge but enough to drop about 2 cup fulls of fluid. So I need to replace the radiator without a doubt at this point.
I have the radiator cover off the top and even when the truck is overheating Only the passenger side of the radiator is hot, I can touch my hand all the way across the top of the radiator, and almost 40% down the radiator before it gets hot.
I am hoping at this point that the radiator just has bad flow and thats causing the overheating issue at this point. The lower hose just seems way to cool if the water really is boiling like it says it is.
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Fleet Owner
Joined: Apr 2008
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From: 0,0,1
The radiator is plugged. Replacing it should solve the overheating problem.
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From: Central NYS
Ditto! And be sure and take at least one of the block drains out and flush it until the water comes out of the block drain clean. Then close it up, fill with water, bring it up to temp, let it cool down and open the block drain again. It will come out b-l-a-c-k!! repeat until heating it to temp produces clean water. (I had to repeat NINE times befor my Navigator flushed clean!)
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