1983 EURO 500sl FLOOR HEAT

[1983500SL]

FOR SOME STRANGE REASON I GET EXCESSIVE FLOOR HEAT AND I DONT KNOW HOW TO STOP IT....

THIS CAR IS NEW TO ME AND I 'M POSITIVE THE AC VENT -HEAT SETTINGS ARE CORRECT...

ANY ADVICE

[kbannister]

Kinda hard to help you without more info. Have you shut your blower off and felt around the heat ducts for heat. Could you have one of those CA emission setups where you have two or three CATs under the car and is one of them heating up? I have a '84 500sl and never notice excess heat on the floor boards unless the heater was running full blast.

[alabbasi]

Have you checked to see if the heat shields are still in place?

[Bondavi]

If your cats are plugged, then the backpressure and resulting heat will build up around the exhaust manifolds/pre-cats. Like kbannister and alabbasi say, check for heat shielding and double check the floor vents when driving just to make sure no hot air is creeping through.

When you say excessive floor heat do you mean you feel hot air or is it the temperature? Pull the carpets behind accelerator pedal and see if the floors are hot to the touch.

[tgolden]

Is your exhaust system composed of original MB parts? Some euros were converted to USA EPA specs with other than MB parts. Is some cases, the converters installed oversized cats to ensure the conversion would pass the EPA Federal Test Procedure. You may have a cat that is oversized or poorly installed on your vehicle and the heat shielding, if still present, may not be effective. Also, if cutting the original exhaust pipes and welding in the modification is how the converter installed the cat, it may be too close to the heat shields. I'm not familiar with the differences between the '83 euro 500SL and the MBUSA models ’83 380SL or ’85 500SL, but MBUSA parts may not fit the euro model; hopefully they do. You need to check the part numbers from the headers to the muffler.

[1983500SL]

Car is original I think and has only 1 converter on one of the pipes underneath.

Could it be that the back pressure from a bad converter can also cause the exhaust gasket to blow because only on that side I have a gasket leak....

As I press on the gas I feel more heat... At idle it is just warm....

Blower motor is off.

Are there any vents that could be open on the floor...If so, I sure can't find them....

[cbdo]

Single question with huge impacts on the answer: Are the floors hot to touch, or is the air coming out the heater vents at the forward end of the tranny tunnel hot?

[kbannister]

The single cat is what I have, replaced the mid muffler. You may be right about a plugged cat but you would really hear an exhaust leak. Is the heat shield still attached to the top of the cat?

I hate to say this but are your floor pans in good shape along with the lower part of your firewall, meaning are there any rust holes in them?

The condition your describe should be somewhat easy to isolate by a process of elimination. The blower is off but is there still heat coming from the ducts, in other words is your monovalve shutting off? If not, you will still get a lot of heat coming from the heater. Is there an exhaust leak, easily detected, start the car, put on the emergency brake and look under it or take it to a shop with a lift to inspect it. Remove your carpets and see if there is any rust up under the dash or under the floor.

Keep us posted

[tgolden]

The car can't be original with a cat. It has been modified. The heat condition you describe indicates exhaust problems. If you live in an area where you can remove the cat, you would be better off restoring the car to original exhaust configuration.

[1983500SL]

Took A Cruise Tonite...got Very Warm And I Checked The Floor... Warm But Not Hot... Feels Like The Faster I Go The Hotter It Gets..

Shield Is On Cat... Solid Floor With The Floor Insulation Still Good...SOLID FIRE WALL..NO RUST AT ALL...NO HOLES...

Could It Possibly Be The Heater Valve Letting Hot Air In But Because My Upper Vents Are Closed .... I Only Feel It From The Floor. I OPENED THE UPPER VENTS AND HOT AIR.

Its Gotta Be Comming From The Front And Not The Under Portion Of The Car...

The Kick Pannels And Under Side Of Dash Is Warmer Than The Bare Metal Floor

PS.. I DO HAVE EXAUST LEAK ON A FEW HEADER GASKETS...

[balsa]

I also have a very hot floor pans. They are very hot on the touch. No rust anywere,the passengers floor changed to new OEM recently. I also get hot air occasionally in the cabin although the AC is off and monovalve have been changed recently. Also the cat's heat plate is on place. The cat does not look or sound like being restrictive . I beleive those V8 cars got very hot due to poor exhaust and cat design positioning and due to the emission laws and engine power.

Balsa

560sl

P.S. I heard from couple of 500sl R 107 owners here in Europe that they have the same problem.

[alabbasi]

On my 6.9 I have the automatic climate control which kicks out hot air even though it's turned off. Some Euro cars also had this. If yours does, it coulld be faulty.

[kbannister]

Originally Posted by 1983500SL

Took A Cruise Tonite...got Very Warm And I Checked The Floor... Warm But Not Hot... Feels Like The Faster I Go The Hotter It Gets..

Shield Is On Cat... Solid Floor With The Floor Insulation Still Good...SOLID FIRE WALL..NO RUST AT ALL...NO HOLES...

Could It Possibly Be The Heater Valve Letting Hot Air In But Because My Upper Vents Are Closed .... I Only Feel It From The Floor. I OPENED THE UPPER VENTS AND HOT AIR.

Its Gotta Be Comming From The Front And Not The Under Portion Of The Car...

The Kick Pannels And Under Side Of Dash Is Warmer Than The Bare Metal Floor

PS.. I DO HAVE EXAUST LEAK ON A FEW HEADER GASKETS...

The fact that the exhaust pipes on these are nearly touching the bottom of the car producing heat is probably contributing to some of your floor heat. I noticed more heat on my floors after adding a cat to get it thru emissions.

I would investigate your monovalve to see if it is shutting off. You could be getting hot water circulating through your heater adding more heat. I doubt that the leaking header gaskets are adding heat in the cabin. The hot air from the upper vents is another indication your heater is the problem.

[Dee8go]

Does the heater in an MB work differently than the one in most other water-cooled cars? I noticed comments here about heat coming through the vents, but I thought that those would only duct air passing through a heat exchanger that is fed byt the car's water cooling system. Are Benz's different in that regard or am I just missunderstanding the comments?

[kbannister]

Originally Posted by Dee8go

Does the heater in an MB work differently than the one in most other water-cooled cars? I noticed comments here about heat coming through the vents, but I thought that those would only duct air passing through a heat exchanger that is fed byt the car's water cooling system. Are Benz's different in that regard or am I just missunderstanding the comments?

As far as I know the Benz is no different that any other car. That is the point of the comments, with the heater supposedly shut off, he is getting heat through the vents. That would lead me to believe that the water is not being shut off from the heat exchanger.