No heat in my car

[Wes Tausend]

...

Mike,

I thought of a couple of added tips.

The way to determine the "in and out" of the heater core is to note which heater hose connects to the bottom of the engine/pump near the main radiator hose that goes to the bottom of the radiator itself. This is the heater-core-out hose since this main radiator hose always draws coolant from the bottom of the radiator. Instead of the funnel/bucket method, I usually feed garden hose water back up this hose to blow out debris. Dirty water will flow out the other disconnected heater hose into a bucket if mess is a concern.

The debris is actually worse after you have run power-flush solution through the system after a long lack of attention, since it loosens up accumulated rust flakes from the engine block. In case performance noticably falls back off, there is often a bit more remaining system junk again "filtered out" by the heater core, partially replugging it again a week later. Tedious, I know.

To check the thermostat and possible excessive thermostat bypass leaks, feel the upper radiator hose (running) when the system has not yet come up to full gauge temperature. Only after the thermostat opens, should hot coolant flow into the top of the radiator, which may have an air pocket (and out the bottom which has a constant liquid supply to feed the waterpump).

If the thermostat and bypasses are operating correctly, there will be no significant hot coolant being wasted in the main radiator unless the engine is up to full temp. When thermostats fail (or are defective when new) they usually fail by staying open. A cold engine may impede heater operation, but may also trigger a computer to continue to run in rich mode, burning more fuel and carboning up the engine.

Nothing is more disgusting than a bum heater except maybe no-start.
I know a lot of guys here wouldn't recommend you feel your hose like that.
But a lot wood.

Wes


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[bomelia]

Well I will look at this tonight. I guess I am surprised that water can flow in one direction through the heater core, and yet not the other direction (at least that is what I am hearing). I do not think the thermostat is bad. I unhooked the bottom hose to drain the system. Then, after the radiator was empty, I started the car. After about 2-3 minutes, water started flowing out of the hose radiator again. Once it emptied, I was able to push water through the system via one of the ports on the heater core.

Mike

[Ron61]

Mike,

I know that this is a dumb question and others may have asked it and I just missed it reading the posts, but does the defroster work? I am not familiar with your cars setup, but in mine the core is inside the car and the defroster gets its heat from the core and it is just changed from heat to defrost with a slider which physically opens and closes a door in the duct work under the dash. If the defroster works, then I would suspect you have a door in the duct work not opening or closing. I am sure this has already been covered in previous posts, but getting to anything in my car under the dash is a real pain in the A**.

Ron

[Barn$nake]

Mike,
I have not worked on a Merc, but several Windstars
and Fords. Pull off the motor for the blend air door (easy)
and inspect the motor and the door coupling.It seems
the trucks would break the arm off the door, but the cars
would break the plastic on the motor.Good Luck
Ed Paz

[bomelia]

Ron,

Air comes out of the defroster (cold).

Paz, I will try that! More and more I am becoming convinced that it is an air flow control problem. I'm still going to blow water through the core in the opposite direction to be sure... but I still do not understand how it could flow one way and not the other.

Mike

[wtm442]

Mike

Dumb assumption ... is the cooling system full of water/antifreeze? My Merc's heater temp was rather luke warm a couple of years ago. Water level was down quite a bit (probably a gallon).

[bomelia]

No, its pretty full. But, I will check again tonight.

Mike

[Wes Tausend]

Originally Posted by bomelia

Ron,

Air comes out of the defroster (cold).

Paz, I will try that! More and more I am becoming convinced that it is an air flow control problem. I'm still going to blow water through the core in the opposite direction to be sure... but I still do not understand how it could flow one way and not the other.

Mike

Mike,

Some of the rust flakes are larger than the holes in the core. These pile up, or gather, up against the small passages on the in side and restrict water flow just as a clogged filter might do.

As in air filters, reversing the flow causes particles to easily "back out" and reopens the major flow. But, just like an air filter, where back-blowing it out with compressed air greatly improves flow ability, some scum and associated particles stick to an extent making core holes smaller in diameter. Usually performance is acceptable after the large flakes depart though.

The consumer power flush chemical is supposed to largely dissolve scum. In severe cases, a radiator shop can "boil" out a core with industrial grade chemicals that would be dangerous to use around the home. And then reseal the leaks that sometimes open with such aggressive treatment.

As an aside, more than you ever wanted to know...

Paper air filters can be repeatedly back-blown and reused nearly indefinately. The filter companies recommend against this and even promote the false idea that a fuel injected vehicle will use more gas because of imperfect flow. Not true. The vehicle may experience less top end power because of less possible total air, but fuel automatically corrects itself to available air.

The "fuel hog" idea lives on because it was commonly believed that a restricted air filter could easily cause a carburated engine to burn more gas. Also not true to a large extent. All common carburators have a tube called a balance tube that sees and merely transfers that same minor "air restricted" vacuum that accumulates above the venturi jets (to "suck" more fuel), also accumulates(transfers) above the fuel level in the float bowl to equally "suck" the fuel from the backside, thereby evening it out. Extreme air filter restriction can defeat this bit of self-regulated engineering. Extreme vacuum would first boil (vaporize) the float fuel, making the float fall down and then suck the gas directly from the gas tank, if the engine could run this long.

And then, there is the idea of back-blowing those in-line under-car fuel filters also. Works just fine and saves buying an expensive new fuel filter against manufacturers "bottom line" recommendation, of course.

I have found that the money saved can be applied to buying a six-pack of "human power flush" to keep plumbing intact. And make the job more enjoyable.

But don't fully flush until the job is successful.

In theory, any filter can be reused in full Red Green philosophy. The one filter I don't recommend back blowing is the oil filter. Don't ask me how I know that, other than I ran out of "flush" early on.

Wes

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