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post #1 of 21 (permalink) Old 06-16-2019, 03:03 PM Thread Starter
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Oooh, that smell!

Guys, I'm a little anxious about what might be something wrong. Yesterday while driving the 300SE home I smelled what I thought might be a forest fire—or maybe an overheated clutch...like you might smell from a big, loaded bus with a manual transmission traversing a mountain. Not quite a burning wood smell, but definitely not oil, either. Thought it was outside the car.

Thought nothing of it until I realized, when I got home, that it’s my car. I popped the hood and looked around but can’t see anything. No evidence of a burn. I looked at all the fuses—nothing. However, when I stick my nose into the space between the fuse box and wiring harness, there was a reasonably strong something-burned smell. There was no evidence of smoke. Smells eletrical-ish, but I’m no expert. This morning the smell was mostly gone—but certainly not entirely.

So it’s a mystery. Anyone have any ideas what it could be? The only other visible anomaly I noticed while driving was that the temp gauge was about 10ļC warmer than usual (around 90ļC), and it wasn’t an overly hot day—80ļF. I had driven the car only a couple of miles to Best Buy and then back.

On a potentially related note (but not likely), in poking around I discovered a weird wire splice coming off the harness; it’s attached to a blue-and-green wire and seems to extend in front of the brake booster and then into another group of wires. However, when I tugged on it a bit, it pulled righto out—and is evidently attached to nothing. I have zero idea whether it’s related to the smell. I assume this has been there for a long time.

I’m afraid to drive the car now because (a) I don’t know what’s causing the burn smell; and (b) this funky wire thing has me concerned as the splice evidently went to another, uh, splice that, as you can see, goes to nothing.

I’m not even remotely qualified as an electrician, so anyone who has a clue and has an opinion or answer is really appreciated. It smells electrical, but then what do I know.

Any help is much appreciated!

Oh, and happy Father's Day to the dads out there.
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post #2 of 21 (permalink) Old 06-16-2019, 04:28 PM
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Originally Posted by Strassenkreuzer View Post
Guys, I'm a little anxious about what might be something wrong. Yesterday while driving the 300SE home I smelled what I thought might be a forest fire—or maybe an overheated clutch...like you might smell from a big, loaded bus with a manual transmission traversing a mountain. Not quite a burning wood smell, but definitely not oil, either. Thought it was outside the car.

Thought nothing of it until I realized, when I got home, that it’s my car. I popped the hood and looked around but can’t see anything. No evidence of a burn. I looked at all the fuses—nothing. However, when I stick my nose into the space between the fuse box and wiring harness, there was a reasonably strong something-burned smell. There was no evidence of smoke. Smells eletrical-ish, but I’m no expert. This morning the smell was mostly gone—but certainly not entirely.

So it’s a mystery. Anyone have any ideas what it could be? The only other visible anomaly I noticed while driving was that the temp gauge was about 10ļC warmer than usual (around 90ļC), and it wasn’t an overly hot day—80ļF. I had driven the car only a couple of miles to Best Buy and then back.

On a potentially related note (but not likely), in poking around I discovered a weird wire splice coming off the harness; it’s attached to a blue-and-green wire and seems to extend in front of the brake booster and then into another group of wires. However, when I tugged on it a bit, it pulled righto out—and is evidently attached to nothing. I have zero idea whether it’s related to the smell. I assume this has been there for a long time.

I’m afraid to drive the car now because (a) I don’t know what’s causing the burn smell; and (b) this funky wire thing has me concerned as the splice evidently went to another, uh, splice that, as you can see, goes to nothing.

I’m not even remotely qualified as an electrician, so anyone who has a clue and has an opinion or answer is really appreciated. It smells electrical, but then what do I know.

Any help is much appreciated!

Oh, and happy Father's Day to the dads out there.
My experience with three W126 SEL 560s is that the original owners spliced in telephones and radar detectors. I have done my best to strip out all of the non-original wiring. Look under your fuse box. That is an area of access often used.
The next issue that I always encountered is previous owners put in new stereo systems with hack job wiring. This issue is painful since it is not always practical to go back to original equipment. Sometimes yes, sometimes no.
You may never figure out the purpose of that wire.
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post #3 of 21 (permalink) Old 06-16-2019, 04:53 PM
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I ran over a tarp in the road on New Years day. I didn't think a lot of it at the time. A couple days later, while approaching my parked car, I noticed the tarp was still under the car.

Turns out it was stuck (melted) to the tail pipe and cat converter.

I pulled it off.

To this day, after a long drive, I still get the burnt plastic smell when exiting the car.
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post #4 of 21 (permalink) Old 06-16-2019, 05:10 PM Thread Starter
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Quote:
Originally Posted by Tom Kaiser View Post
My experience with three W126 SEL 560s is that the original owners spliced in telephones and radar detectors. I have done my best to strip out all of the non-original wiring. Look under your fuse box. That is an area of access often used.
The next issue that I always encountered is previous owners put in new stereo systems with hack job wiring. This issue is painful since it is not always practical to go back to original equipment. Sometimes yes, sometimes no.
You may never figure out the purpose of that wire.
Thanks, Tom. The only funky wiring that I'm aware of this car was a poor job fixing the AC about 15 years ago and as a result, it was hard-wired in the on position--which burned it out pretty fast. This car was bought new by my mother, so I know that the only after-market thing done to it was my addition of a Pioneer head unit about four years ago--and thus far no problems. This is why this problem is kinda baffling; there would be no reason for the installer to splice in a wire from the harness as the old stereo had both power and light/antenna inputs. That spliced wire is odd.

Anyone know what that particular blue/green wire did? I'm sure the wiring diagram shows it, but I have no clue where to get one or how to read it. That would at least help understand what someone was trying to do with that splice--back whenever it was done. Could have been any time during the last thirty years.
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post #5 of 21 (permalink) Old 06-16-2019, 07:24 PM Thread Starter
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Originally Posted by LostInTime View Post
I ran over a tarp in the road on New Years day. I didn't think a lot of it at the time. A couple days later, while approaching my parked car, I noticed the tarp was still under the car.

Turns out it was stuck (melted) to the tail pipe and cat converter.

I pulled it off.

To this day, after a long drive, I still get the burnt plastic smell when exiting the car.
Good idea. I looked with a flashlight and can't see anything. But I'll have another look tomorrow with daylight. That would please me no end to find out it's just something that wound up melting on my cat or exhaust pipe. Somehow I'm not terribly optimistic, though if one applies Occam's theorem, then I might be pleasantly surprised.
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post #6 of 21 (permalink) Old 06-16-2019, 09:15 PM
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Quote:
Originally Posted by Strassenkreuzer View Post
Guys, I'm a little anxious about what might be something wrong. Yesterday while driving the 300SE home I smelled what I thought might be a forest fireóor maybe an overheated clutch...like you might smell from a big, loaded bus with a manual transmission traversing a mountain. Not quite a burning wood smell, but definitely not oil, either. Thought it was outside the car.

Thought nothing of it until I realized, when I got home, that itís my car. I popped the hood and looked around but canít see anything. No evidence of a burn. I looked at all the fusesónothing. However, when I stick my nose into the space between the fuse box and wiring harness, there was a reasonably strong something-burned smell. There was no evidence of smoke. Smells eletrical-ish, but Iím no expert. This morning the smell was mostly goneóbut certainly not entirely.

So itís a mystery. Anyone have any ideas what it could be? The only other visible anomaly I noticed while driving was that the temp gauge was about 10ļC warmer than usual (around 90ļC), and it wasnít an overly hot dayó80ļF. I had driven the car only a couple of miles to Best Buy and then back.

On a potentially related note (but not likely), in poking around I discovered a weird wire splice coming off the harness; itís attached to a blue-and-green wire and seems to extend in front of the brake booster and then into another group of wires. However, when I tugged on it a bit, it pulled righto outóand is evidently attached to nothing. I have zero idea whether itís related to the smell. I assume this has been there for a long time.

Iím afraid to drive the car now because (a) I donít know whatís causing the burn smell; and (b) this funky wire thing has me concerned as the splice evidently went to another, uh, splice that, as you can see, goes to nothing.

Iím not even remotely qualified as an electrician, so anyone who has a clue and has an opinion or answer is really appreciated. It smells electrical, but then what do I know.

Any help is much appreciated!

Oh, and happy Father's Day to the dads out there.
Down deep under the brake master cylinder is a big resistor screwed to the body. I'd take a look at that. I think they can get hot enough to start leaves on fire that collect down there. Great pics, by the way.
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post #7 of 21 (permalink) Old 06-18-2019, 07:59 AM
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Originally Posted by luckymike View Post
Down deep under the brake master cylinder is a big resistor screwed to the body. I'd take a look at that. I think they can get hot enough to start leaves on fire that collect down there. Great pics, by the way.
That's exactly what I was thinking. To keep that area clean I vacuum it each time I vac the interior during a wash job. Use a crevice nozzle and go in where it will fit, different angles to get all the way to the bottom
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post #8 of 21 (permalink) Old 06-18-2019, 11:10 AM
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Drive it around the block a couple times and see if any of the rims get hotter to the touch than the others. Might be a sticking calliper.

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post #9 of 21 (permalink) Old 06-18-2019, 12:57 PM
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tip on cleaning all of those areas back by the firewall, under brake booster, crevices behind the battery, etc...Vaccum usually isnt strong enough to get ALL the leaves, needles from pine trees, etc.
But, an air compressor with a skinny blower attachment can get ALL of the stuff blown up and out from back/under there. I usually toss an old bedsheet over the entire engine area before using this method so that all of the various dirt, leaves, etc end up on top of the sheet for easy disposal vs falling back down into the engine bay
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post #10 of 21 (permalink) Old 06-18-2019, 01:53 PM
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Blow definitely works best in this case.
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