Heater

[Largeowner]

Since I bought my 67 230 SL the heater has been "less than adequate".  I finally attempted to track down the problem over the weekend.  What I discovered was:

1.  That the shutoff valve to the heat exchanger seems to be working perfectly. 
2.  The heat exchanger gets warm to the touch.
3.  There is very little air flow to either the floor or the windshield even when the intake vent is all the way open, or the fan is switched on.
4.  That "very little" air flow is lukewarm at best.

I am thinking that I might have ductwork leaks, but if those leaks are within the cabin it should still get warm inside.  I am also wondering if there could be some blockage that sends the air "around" the heat exchanger instead of "through" it resulting in the lukewarm air.

Do any of the members have a diagram of the heater ducting?  I would also love to hear any suggestions.

Thanks,

Large

[scoot]

Well, this isn't intended to sound insulting so please don't take it that way, but are you SURE that you have the fan turned on all of the way?  Do you hear the motor turning at different speeds depending on which of the two knotches the fan knob is in (and the variable area between 0 and 1)?   

Also, open the lever that lets the fresh air into the intake and then get out of the car and look to make sure that the intake flap is open and that there isn't a racoon or something clogging up the air intake...

I had recently been annoyed at my heater for not getting hot.  Replacing the car thermostat helped quite a bit, but the heater still doesn't get all that hot.  Adequate but not like a modern car.

[hkollan]

The heat exchanger could be partly clogged, preventing sufficient waterflow to heat it fully.
(That was the case on 2 out of 3 heat exchangers I had restored at a radiator shop) 
Also to prevent air leaks in the ductwork, insulating rubber foam is used to seal the different parts of the heater box.
This foam turns dry and brittle and disintegrates and the remains could prevent the flow of air to the intended locations.
Unfortunately there's no easy way to remove these parts for inspection and repair.

[Desertpagoda]

Sounds depressing like mine! A 1966 230sl.
 I had all the same thoughts as you did. Even removed the core (hours&hours) to have it opened and cleaned, replaced the foam seals between the core and housing...no better!
 It is better than nothing, but not by much!
                                                                     kb

[Largeowner]

I can clearly hear the fan working and it gets faster as I go through the settings.  I had the fresh air vent completely apart last Summer to fix the plugged rain water drains so I know that is not the problem.

I think I will try a chemical flush of the cooling system (including the heater core) as the next step.

Thank you all for the suggestions.

Large

[graphic66]

I have a 66' 230SL and I rebuilt the heater completely. I have the option # 493 Heavy-duty heat exchanger, US-version. The car has incredible heat. It really get very comfortable and you don't need it to run on high. The cold weather I drive in is Upstate New York Spring and Fall, sometimes in the 20'sF. Does anyone know what exactly the 493 option included.
    Some issues may be a blocked heat exchanger, maybe a good flushing will help. I have pulled two of these heat exchangers from 113's and both had broken mounting brackets on the heater core. A little solder and they were in good shape, ready for another 40 years. I would think if you pulled it out you could check the circulation with a hose running hot water through it and check the temp with a laser temp gun like you would a radiator.
     When I pulled mine I made a plug for one end and a tire valve on the other end, I pumped it up to 20 PSI and they held overnight. On a side note a great way to pressure check a radiator is by putting a mountain bike inner tube cut in half over the radiator inlet and outlet with the other holes plugged. Pump up the tube and let it set overnight. Thinking about this it would also work with the heater core, you could use a road bike tube cut in half, each end clamped to the heater core inlet and outlet. Pump it up and let it set. You could do this check with it in the car.
   The first thing I would do is unhook the inlet and outlet on the heater core and hook the garden hose to one end and give it a good flush. You could see right away if it were completely plugged and if your water valve was opening. The lever on top of the valve in the heater core can be put on 4 different ways, only one is correct. It is possible someone reassembled it wrong. I put a short hose on mine and blew through it while changing the heater settings to verify that it was working when I replaced the valve in the heater core. Jus be extra careful not to push the valve body into the heater core, that would be a disaster.

[asjmplisson]

I have to re-do my entire heater system :
heat exchanger
Blower + motor + impeller
Defrost nozzle
Air flaps

Does any one knows where I can find the parts ? mostly the blower ?
I'm in the US

1965 230sl Automatic

Thanks

[cascadia]

I've seen some of these parts on ebay recently, it might be worth a look there.

[Jonny B]

Check with Walt Klatt, he has a number of parts to sell. You can send a message to him from the members section of the forum.