Author Topic: How to reduce heat inside the cabin? (Read 24633 times)

dngalura · « **on:** November 03, 2006, 23:08:11 »

Gentlemen,
I have this overheating inside the cabin, I think it's coming under the dash. The heaters are closed, but it still get hot. Could it be that the flaps on the heater are not closing properly? How can I reduce this or eliminate it? Getting into the heater core is difficult. I was reading the forum and one of the discussions was on this issue and one suggestion was to install a T-bypass hose between the ingress and egress of the water system going into the heater box (Jeffc280sl ?)Does it work? Please elaborate or any suggestion. Thank you.
Dan G '70 280SL

Tom · « **Reply #1 on:** November 04, 2006, 07:58:04 »

These cars have very little insulation between the engine and the cabin and the engine throws off a lot of heat. While you may have issues with the flaps or the heater core not closing fully (i.e. moving the bottom left lever all the way to the right), it is difficult to substantially reduce cabin heat. (edit-in the engine area on the firewall, there is a rubber plug about 2 inches in diameter. Remove the plug and see if your linkage that closes the heater core valve needs to be adjusted.)

I have added reflective foil backed insulation, added Dyna-mat and replaced my carpet and this seemed to help a lot with noise and heat. I provided extra insulation at the transmission tunnel-I have an automatic and the chrome plate at the gear shift still gets quite hot-this is the way these cars are.

Not sure I added much but it's probably nothing wrong with your car, it's pretty much the way these cars are.

1971 280sl Tunis Beige Metallic (restored & enhanced)
1971 280sl Tobacco Brown (low mileage stock)
1970 280sl Beach Driver with a touch of rust

dngalura · « **Reply #2 on:** November 04, 2006, 10:30:19 »

Thanks Tom, I'll look into that rubber plug. Never knew what it is for.
Dan

dngalura · « **Reply #3 on:** November 04, 2006, 21:09:23 »

Dear Tom,
I found the rounded rubber cover, and removed it and found that the lever is disconnected from the round metal gismo. What is this? I can see a square thing and in the center is a hole, looks like this is were the other rod is connected. The center screw is missing. Does this square thing moves? I try to moved it with a long nose plyer, it won't move.
I also moved the lower lever inside the car and it moves this rod.
How do you re-connect this rod to the round gismo. What kind of screw(metric) and size, only if you know.
I was also reading the forum and a discussion about this is there re: heater valve, on or off.
Anxious to hear from and the group. Thanks Dan

DavidAPease · « **Reply #4 on:** November 04, 2006, 23:06:49 »

Dan,

You need to read up on how the heater works. Search the forum for lots of good info. I will try to get you started:

The round gizmo with the square on the top is the heater core valve. This gizmo must turn in order to turn the hot water (heater) on and off. The square on the top attaches to an arm with a square hole in it, which in turn attaches to the dash heater lever linkage, to turn the valve. The hole is for a screw to hold the arm to the valve. If you look at the photo in Bob Possel's "Heat On/Off?" thread, you will see the arm screwed onto the valve.

Here is a write-up from George Davis that gives some details on removing and refurbishing this valve:

http://www.sl113.com/forums/index.php?topic=2514,heater,core,valve

If you cannot rotate or remove the valve, there is a very cool procedure that involves putting together an "extractor" tool; if you need it, I will find the description.

There is lots of info on this subject in the forum. If you need more direction, I'm sure we can point you to it. Good luck!

-David Pease
'66 French 230SL

Cees Klumper · « **Reply #5 on:** November 04, 2006, 23:37:29 »

For what it's worth - my car does not get hot inside even in summer (other than from the true ambient temperature), as long as I have the heat off. On my car, a previous owner installed an extra manual on/off valve in the hose in the engine compartment right before it goes into the firewall to the heater box, because the original heater valve is frozen. I have not gotten to repairing it yet, also because the manual valve works so well. I just close it in the summer and open it in the winter. I will take a picture of the extra-added valve and post it here sometime in the near future.

Closing holes in the firewall (there are many as conduits for cables etc and sometimes rubber plugs are missing) will cut down noise considerably and, I guess, also some 'stray' heat. Then, there are the 2 aluminum plates in between the exhaust pipes and the car floor that, when not in place, will make a difference in the amount of heat entering the passenger cabin.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

dngalura · « **Reply #6 on:** November 05, 2006, 00:54:45 »

Thanks to Tom, David P, and Cees K,
I read all your comments and leading me to forums discussions, I now am ( I think) well equipped to tackle this issue. I hope the heater valve will be fixer friendly, with all the tricks and cautionary measures. I'll keep you posted.
thanks again.
Dan

bpossel · « **Reply #7 on:** November 05, 2006, 06:58:53 »

Hi Dan,

Read my updated post on the heater valve (Heater Valve - Heat On/Off). Overall an easy job, if you follow the advice of this site and be careful not to drop the valve into the core.

We all know that these cars get hot in the cabin... but I also noticed heat coming out of my vents during the summer months, making it all that much hotter inside the cabin.

As I replaced my heater valve o-ring I noticed that the old rubber ring was completely flat (squished). The new rubber o-ring is round and should provide a nice clean, tight fit against the valve side wall. I am hoping that the new valve o-ring will now stop and start the heat flow, as needed, and help the valve work more efficiently.

While working in this area, I also ended up replcing the rubber around my air flaps. The old rubber was worn out and some pieces missing. The new rubber will make a nice seal. Also replaced the rubber around the main, large air scoop vent plate. Now when I close off the outside air, it really stops the air from coming into the cabin.

Good Luck!
Bob

bpossel (Memphis, TN.)
'71 280SL / '97 E320

Naj ✝︎ · « **Reply #8 on:** November 05, 2006, 07:41:28 »

quote:
From Cees:
For what it's worth - ..... On my car, a previous owner installed an extra manual on/off valve in the hose in the engine compartment right before it goes into the firewall to the heater box, because the original heater valve is frozen. I have not gotten to repairing it yet, also because the manual valve works so well. I just close it in the summer and open it in the winter.

Here's one I saw on a 107 fitted with a diesel engine [

!]

Download Attachment:

BurghHse086.JPG
42.31 KB

naj

68 280SL

Cees Klumper · « **Reply #9 on:** November 05, 2006, 17:28:43 »

Hello Naj - yes, it's somewhat like that, although not quite as rudimentary (the one in the pic looks like a fire hydrant valve!). But that is how mine works as well and, again, it is very effective as long as you don't mind getting under the hood a few times a year to operate it.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

dngalura · « **Reply #10 on:** November 05, 2006, 23:42:27 »

Gentlemen,
For now, the simplest way ( I think ) was to connect a open/closed valve to the ingress hose to the heater core. I got one from the plumbing department at Home Depot and connected today and it works.
the weather here in Southern California is still warm, this makes riding more pleasant. I still plan to work on the heater valve when time permit.
Thank you all.
Dan

JamesL · « **Reply #11 on:** November 06, 2006, 11:19:10 »

I put some funky house insulation under my carpets - not over the tranny tunnel as it makes the carpet fit poorly.

Basically it reflects/absorbs some of the heat and makes the cabin far cooler

(an earlier version of this:http://www.tri-isosuper10.co.uk/)

waltklatt · « **Reply #12 on:** November 06, 2006, 12:54:52 »

Dan, check under your car to see if the fragile aluminum heat shields are in place. Check the proximity of the pipes to the floors-might be too close.
Walter
1967 220SL-diesel

hands_aus · « **Reply #13 on:** November 07, 2006, 05:56:37 »

There are usually 3 under dash panels?

I used silver lined 25-30mm thick foam to line them. This reduced lots of noise as well as summer heat.

These panels are available new.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

blue230sl · « **Reply #14 on:** September 14, 2008, 12:23:45 »

has anyone used DYNAMAT to line the under dash panels? if so did it work well to reduce noise and heat?

quote:
Originally posted by hands_aus

There are usually 3 under dash panels?

I used silver lined 25-30mm thick foam to line them. This reduced lots of noise as well as summer heat.

These panels are available new.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

graphic66 · « **Reply #15 on:** September 14, 2008, 15:16:24 »

I put the Dynamat every where I could stick it in my interior under the carpet. I put new pads under the carpets and lot of insulation also. There a many of the pads for the firewall. I think there are a couple in the engine compartment below the top pad that can only be replaced with the engine out. There are also more under the dash. The Dynamat does work very nice and I am happy with it.

seattle_Jerry · « **Reply #16 on:** September 14, 2008, 20:46:41 »

I used dynamat on my 220D. Inside the doors on the interior of the door skin and the outside of the interior door metal. I put it in my trunk lid and all interior metal trunk surfaces.

On the floor boards I used dynamat, a dense foam, factory carpet, and mats. It was probably 1.75" thick. Really quieted the car down. The floor boards seemed like they made the most difference.

paulr · « **Reply #17 on:** August 08, 2009, 20:14:16 »

Quote from: naj on November 05, 2006, 07:41:28

From Cees:
For what it's worth - ..... On my car, a previous owner installed an extra manual on/off valve in the hose in the engine compartment right before it goes into the firewall to the heater box, because the original heater valve is frozen. I have not gotten to repairing it yet, also because the manual valve works so well. I just close it in the summer and open it in the winter.

Here's one I saw on a 107 fitted with a diesel engine [!]

naj

68 280SL

Hi Naj

is this really as straight forward as just putting an inline valve in ?

jeffc280sl · « **Reply #18 on:** August 09, 2009, 14:15:54 »

Paul,

I'm convinced my heater control valve leaks so that even in the off position hot water from the engine is cycled through the heater core and into the cabin. Some of us have installed a heater bypass hose on our cars. Utilizing a 3 way valve like the one in the picture below you can control the flow of hot engine water by routing it to the heater bypass hose and/or the heater core. You will need to buy a T fitting and a piece of heater hose also. Make sure you buy a T port type valve.

DavidBrough · « **Reply #19 on:** August 09, 2009, 17:31:27 »

You might want to try one of these, I have one in my heater bypass hose.

http://www.cbsonline.co.uk/heater-valve--15mm-58-htrv15-479-p.asp

jeffc280sl · « **Reply #20 on:** August 09, 2009, 17:59:39 »

David,

That looks like a perfect valve to use in my current bypass setup. I have a similar stop valve but I can not control water going to the heater core. My original thinking was that the heater core valve would do that. But since I think my heater core valve is leaking I want to control the flow of water to it. Another member told me about 3 way valves so I have decided to go that way. The 3 valve will replace the T fitting for water coming from the head and the shut off valve that currently sits over the head cover. With a T port 3 way valve I will be able completely close off hot water going to the heater core and route it to the bypass hose. When open the valve will permit hot water to flow to the heater core and bypass hose.

paulr · « **Reply #21 on:** August 10, 2009, 21:12:51 »

thanks for your answers. I have put one of 'David"s' taps inline on the pipe going into the heater and turned it off so that no water goes past the firewall. The idea being that when I need heat I simply turn it on. I haven't done the T thing as the engine is cool enough and hasn't blown up in the 25 miles I've done since.

So, at last, no more wafts of sickening heat at my feet.

It was that simple................

jeffc280sl · « **Reply #22 on:** August 14, 2009, 17:40:32 »

Went ahead and installed a SS 3 way valve like Awolff280sl suggested so that I can shut off the flow of hot water to the heater core and direct it to the bypass hose. Here is a pic. I'll find out soon if it solves my cabin heating problem and advise.

graphic66 · « **Reply #23 on:** August 15, 2009, 02:54:55 »

Wow, that is one ugly valve setup. Sorry, but I would rather be hot than open the hood and see that contraption. There must be a better way. Probably just fix the original valve.

abe280SL · « **Reply #24 on:** August 15, 2009, 05:31:23 »

Kind of agree with graphic66....sorry but that looks ugly. I have a similar problem in my bmw 73 csi E9. In those cars the circulation of hot water into the heater core is continous...cant shut it off, no valve. You get the hot air by turning on the fan...but water still circulates no matter what. I thought of a valve like that...but just cant get myself to do it an mess up the looks of the engine compartment.
abe

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Author Topic: How to reduce heat inside the cabin? (Read 24633 times)

dngalura

dngalura

dngalura

dngalura

bpossel

dngalura

blue230sl

graphic66

seattle_Jerry

paulr

jeffc280sl

DavidBrough

jeffc280sl

paulr

jeffc280sl

graphic66

abe280SL