Significantly improved luke warm heat (without heater core replacement)
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12-12-2018, 04:59 PM
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Significantly improved luke warm heat (without heater core replacement)
Hey all,
Figured I would pass along this success. I have been fighting luke warm heat in the 99 I bought recently (5.9 liter). I have read that you're basically destined for a heater core change in this situation. I recently changed coolant it seems to have made the issue even worse.
Today I drained a a bit of coolant from the radiator and disconnected the heater core return line from the water pump (driver side, feeds into the top), and found a section of the heater core input hose on the passenger's side of the motor which had two hose clamps around a pipe fitting. Disconnected that so now I had access to the isolated heater core without accessing the firewall. Here's what I did.
1. Put a bucket under the input line and blew out all the coolant (using my mouth separated from the hose by my hand). Probably held a pint or two.
2. Duct taped a garden hose to the heater core outlet and ran water backward through it for a few min. I didn't run full pressure. I just cracked the spigot open, then maybe increased to 1/2 turn open. No idea how many PSI that is but the water was coming out of the input hose and making an 18 inch jet or so.
3. Again blow out the water using my mouth.
4. I stuck the inlet hose into the air by shoving it behind the transmission dipstick (sticking strait up in the air). I pulled the return hose out from behind the motor and got access to all of it. Just needed to be snaked behind a wire loom. Then I used a funnel and filled the heater core with zyrtec 10 minute radiator flush (full strength) while holding the return hose up in the air a bit (to get a good fill). Left it sit an hour. Used about 2/3 of the bottle for this (which is 22 ounces when full).
5. Microwaved about a quart of water with what was left of the zyrtec until it was boiling. Flushed the first bit of zyrtec out with this. Let it sit another hour.
6. Backwards flush with water as in #2.
7. Funnel filled the heater core with 50/50 coolant and hooked everything back up. Topped off the radiator (or at least tried to, it really didn't take anything).
Result: its probably not as good as a heater core replacement. But using my temp gauge, my vent temps went from between 91 and 94 degrees to 125-135 degrees. Driving around it was warm enough that if I left it on at full I would eventually want to turn it down because the cab was getting too hot.
So I don't know if this is old news to everybody or if it will work for everyone. But it cost me 7 bucks and it worked for me.
Figured I would pass along this success. I have been fighting luke warm heat in the 99 I bought recently (5.9 liter). I have read that you're basically destined for a heater core change in this situation. I recently changed coolant it seems to have made the issue even worse.
Today I drained a a bit of coolant from the radiator and disconnected the heater core return line from the water pump (driver side, feeds into the top), and found a section of the heater core input hose on the passenger's side of the motor which had two hose clamps around a pipe fitting. Disconnected that so now I had access to the isolated heater core without accessing the firewall. Here's what I did.
1. Put a bucket under the input line and blew out all the coolant (using my mouth separated from the hose by my hand). Probably held a pint or two.
2. Duct taped a garden hose to the heater core outlet and ran water backward through it for a few min. I didn't run full pressure. I just cracked the spigot open, then maybe increased to 1/2 turn open. No idea how many PSI that is but the water was coming out of the input hose and making an 18 inch jet or so.
3. Again blow out the water using my mouth.
4. I stuck the inlet hose into the air by shoving it behind the transmission dipstick (sticking strait up in the air). I pulled the return hose out from behind the motor and got access to all of it. Just needed to be snaked behind a wire loom. Then I used a funnel and filled the heater core with zyrtec 10 minute radiator flush (full strength) while holding the return hose up in the air a bit (to get a good fill). Left it sit an hour. Used about 2/3 of the bottle for this (which is 22 ounces when full).
5. Microwaved about a quart of water with what was left of the zyrtec until it was boiling. Flushed the first bit of zyrtec out with this. Let it sit another hour.
6. Backwards flush with water as in #2.
7. Funnel filled the heater core with 50/50 coolant and hooked everything back up. Topped off the radiator (or at least tried to, it really didn't take anything).
Result: its probably not as good as a heater core replacement. But using my temp gauge, my vent temps went from between 91 and 94 degrees to 125-135 degrees. Driving around it was warm enough that if I left it on at full I would eventually want to turn it down because the cab was getting too hot.
So I don't know if this is old news to everybody or if it will work for everyone. But it cost me 7 bucks and it worked for me.
Last edited by 87Beast; 12-12-2018 at 05:02 PM.
