I's gots no HEAT!!!!! 99 f150 4.6L mech sez heater core could be plugged/ clogged. anyone have any suggestions or is the only option to pull the core out and replace it and how big a pain in the ars is that?????? Kinda want to get this problem solve before we have the hard freeze and ice!!!!!!

 

At feed and return hoses.
Is the return very cool and the feed somewhat heated?
If yes, either the core is air locked or plugged.
If the coolant has not been changed at reasonable intervals, this may be the reason the core is blocked.
I have had sucess on occasion back flushing using the right weak acid solution to clear them to usefulness.

 

What kind of weak acid?????? Do i run it thru the "hot" hose???? do i need to drain the coolant??????

 

In oder of there strength.
HI-Muratic acid deluted.
Radiator flush.
Lo-Lemon Juice. This is an acid in reality and attacts lime type deposits.
You will have to drain the coolant down far enough to open the hoses to the heater core and attach you own hoses to the core then run the cleaning agent through in reverse.
Note the flow rate at the beginning. As it opens the flow rate should begin to rise.
A lot of fooling around but it might save the work of replacing the core.

 

Grayd73, hey man, i just had the same problem!! its funny how this post starts coming up when the weather gets cold. i changed mt rad. and my thermastate. cause of a leak. but that didnt help my heat so i back flused the heater core and that gave me enough heat till i save up some money,cause im told this is the one thing thats worth paying someone to do.

they have a kit at autozone made just for back flushing. it was cool but i think i had the best luck just putting my garden hose up to the heater core hose.

with the motor turned off i took undid the big hose coming baack to my rad. then undid the heater core hose and just blasted water threw there.

its not perfect but its alot better than it was. thanks to the guys on here i a little warmer!!!

hope it helps a little
travis

p.s. check my thread on page 2 or 3 "no heat"

 

what else could cause the no heat deal....... after driving around this morning i popped the hood and both heater hoses felt "Hot" i ask my mech and he asked if i could hear the "heater door" open as i adjusted the temp **** from cold to hot?!?!?!? has anyone run into this????

 

Unless you have a silent engine and your ear pressed against the dash, you're not going to hear the valve open when you crank the dial to hot. You might feel the valve opening through the ****, but you won't hear it.

If you haven't changed the coolant at regular intervals, every 60k or so, the heater core getting clogged is a common problem. You'll have to drain the coolant level to below the pump, then disconnect both hoses to the core and let it drain a bit. Pour the acid mix into the return line and wait for it to flow out the intake. If it's working, the flow will gradually increase. If not, then you have to replace the core.

 

just remove both heater core hoses and connect a garden hose to one end and flush it. If in a second it doesn't flow, stop and flush from the other side. most clear up and make sure you bleed all the air from it when done. If both hoses are the same temp than the heater core is probably flowing. you would then have a blend door problem. If you have the auto HVAC the shaft on the blend door likes to break. If you have the manual HVAC the **** for the temp selector cracks, just swap the **** with the fan **** and see if it works