POLL: Heat....Hot or Cold? & Optimizing Heater for Winter

[Kayvan]

In preparation for chilly months ahead....and help extend driving into early Winter.

It seems like the SL heater produces heat to varying degrees. in reading past posts there seem to be some folks who have toasty interiors (one has Havy Duty unit) in very cold climates (NE USA, Europe) and those who note weak heat not up to modern standards.

I was wondering if there is a checklist to "optimize the heater"

-make sure heater valve is not frozen / seized
-check geometry of heater valve rod: to be certain its fully "ON"
-make sure heater cables are fully shutting off cold air flow (possible?)
-check heater core for obstructions / flow / leaks
-Check blocked/disconnected inner air ducts/foam-seals
-Check radiator/coolant levels
-Check thermostat; not missing or stuck OPEN

I seem to remember my original heator core as "HOT" enough to drive with the heater on and the top down in late fall. I had to have it replaced as it eventually sprung a leak.

Now I have a new M-B OEM heater core, new heater levers, cables, and the heat output is anemic at best.  In NYC November of last year, I had to have the window defroster on to full fan to help keep it warm. My heater valve is in a new heater core and I assume its set up accurately; I dont get hot air flow in summer; my car runs cool with Temp barely over 180-200.

[Kayvan]

anyone getting HOT heat or have tip?

[J. Huber]

Well, I am hesitant to vote because I fall somewhere in the middle. My heat works pretty well -- but frankly nothing like my modern F-150 or the like. My two fan speeds are only slightly different from each other. I have had the heater worked on (wallet still a little sore from that one!  ) and I'd say it "works" -- period. Recommend gloves and a coat if you really want to be toasty... or perhaps put the top up 

[jeffc280sl]

I've recently run up against low heat problem in a Jeep Cherokee and Buick Park Avenue.  In both cases a clogged heater core was the problem.  It was interesting that in both cases there was a good flow of water through the core. Both heater cores had the in flow and out flow pipes right next to each other.   I determined there was sediment in the bottom of the heater core.  I think the sediment was such that the hot water didn't circulate fully through the core and just came in and went out without fully warming it.

Our inlet and outlet design is different in that they are located on different ends of the core.  They are however mounted on the top side of the core and if sediment were present and the car sat for extended periods it would settle in the lower part of the core resulting in poor circulation.

Just something to consider.

.

[J. Huber]

Well, in the name of science, I decided to test my heater last evening (nice excuse for a drive! 

It has been rainy and chilly here for a few weeks now but last night I looked up in the sky and saw stars and an awesome full moon and said "time the Pagoda got a little exercise...")

Anyway, it did not take long and the heater was working pretty well. The problem I think in my car at least is the heat only comes out the back of the footwell. With the dash panels on, I had to reach my hand way under to feel the warm air blowing. It was nice and warm down there and had some velocity (if thats how you term it). Modern cars seem to have more warm air coming at you -- with my car, it was definitely primarily down under. But it works!

By the way, for even you long-time owners, but especially newbies: find an excuse to take night drives once in a while. There is nothing like the colorful dash and way the car looks and feels at night! I bet a lot of us take mainly daytime spins. Try it, you'll like it!

[dean]

Hi James,

Funny you mentioned driving the Pagoda at night!.  Yesterday i was forced to do just that in freezing cold NE

My wife took the clk for some errans, and accidentally she also took with her the keys of the rangerover, that left me with the keys of my 68 280 SL, to give my daughter a ride to her Friend's.

i tried to put the heat on but i have to admit i need to figure it out the proper way of positioning the levers as i did not feel warm air coming out, mind you that yesterday it was 16 degrees F not accounting for the wind chill factor.  i thought to my self the dashboard is dimly lit to see clearly what is the right position but the blue and red lights and the dim dashboard looked really nice and enjoyed the night trip in the freezing temperature and did not mind the cold nor that i did not feel  the hot air....

[Kayvan]

Wow lukewarm heat has overtaken Hot heat?

For you HOT heat guys...care to share your secret.....ie, nothing.. just flip switch since day 1, or re-core or shorten/lengthen rod controls, fresh air flap, etc

You might need the luke warmers help in the summer when you are overheating!

[Garry]

As one of the very hotters, all I can say is that when doing my restoration, I had the radiator re cored, with the engine out I had its water jacket chemically flushed, and I replaced all pipes and hoses and now with the outside temp in either low 30's f or very high 100f-110f (say that again 110f as I took it out that day) the temp guage always sits on 180 + - 5 degrees whether in traffic or not and if I put the heater on with fan on I get great heat, top down or up.  Maybe its luck of the draw, but I believe it is all to do with how good your water flow is.

[ted280sl]

Years ago I found that I was unable to fully turn offmy heater. It seems the "O" ring on the heatre core valve was frozen. After I got it unfrozen and replaced the "O"ring I found that I still could not turn off the heat because the heater valve adjustment bar was improperly adjusted. I connected the heater core to a water hose. I then adjusted the heater core valve until the water stopped coming out of the heater core. I also found a that position that when I turned the heater core valve on I got more water and heat running through it.
  I hope this informaton helps.
Ted
1969 280SL

[Kayvan]

Drove my SL on Sat night with 45 degree temps.

With Air Flow to Footwell, heat was much hotter than to Dash/Defroster vents.

Not sure if outlets are larger or Windscreen deflection cools the air, but heat was much hotter, and volume much greater
 

For you guys with low heat try this and make sure levers are correct position per manual.