i have a 98 ford taurus 3.0 OHV. The heater is not getting HOT. its warm, but when i turn the temp **** down, it gets cold before it gets in the blue. I replaced the thermostat, added new antifreeze, and replaced the radiator cap. i don't see any leaking in the passenger floorboard. I don't know what else to do other than getting into a mess with the heater core. HELP!!

 

One thing you could try is to disconnect or cut the the heater hoses about half-way between the firewall and the engine block, quickly plug the hoses from the block and water pump. then rig up to pour a radiator flush thru just the heater core, you may have to use a little compressed air at times to get things moving. Try lots of things if you need to, vinager, or coffee maker cleaner, or radiator flush, what ever it takes. give the solutution plenty of time soak and eat away at the build up. I did this years ago on a Dodge Intrepid and had pretty fair results, altho not as good as replacing it was a vast improvement.

 

The most common cause of such problems is an air bubble or any other obstruction trapped in the cooling circuit, preventing a normal flow through the heater core. The first thing you should check, imo, would be to make sure there's no air trapped in the heater core hoses. This can be done by simply disconnecting the higher hose, with the engine off, and filling the cooling system through the expansion tank (not the radiator cap, that stays in place) until you no longer get air bubbling out of the disconnected hose. Put the hose back and start the engine.

The easiest way to do this - and many cars in the old days were fitted with this - is to have a bleeder installed on the hot connection of the heater core. This is a screw-type release cap installed on the hose, you would just open it slightly and let the engine run (and spit out coolant) until there was no more air coming out. You can still get one such part from the junkyard.

The other thing that can happen in your case, however, is that the engine's thermostat is bad, which means your engine never reaches the normal temperature. I've seen this in a few cars, and the problem is severe, as it may cause serious damage to the engine in the long run. Fortunately, this is easy to troubleshoot: start your COLD engine and let it idle. Pop up the hood right away and grasp the upper cooling hose connecting the radiator to the engine. STAY CLEAR OF THE RADIATOR FAN IF YOU CARE ABOUT YOUR FINGERS !! This hose MUST REMAIN COLD until the engine reaches the normal operating temperature, at which point it'll heat up really fast. If you feel it warming up as the engine warms up, this is proof that your thermostat stays open, so the engine never reaches the normal temperature - and neither does the heater core, thus your problem...

Let us know how it goes, and good luck!

 

This may work well too - just keep in mind that the engine has many aluminum parts exposed to the cooling circuit, so you'll need to flush the heater core very thoroughly before reconnecting it back, or traces of the corrosive cleaners you used for the heater core will eat away at your engine. I agree that they'll be diluted, however they will still be attacking the aluminum parts aggressively because of the high temperature of the coolant (which facilitates corrosion big time) combined with the long-term exposure (how often do you flush the cooling system?).

I would suggest you flush the heater core in place with cleaners followed by plenty of high pressure tap water (put a garden hose and a drain hose on it and let the water run) until you get no more muddy water coming out. HTH ...