StevenL5975

Hello,

well as the title explains I can smell burned plastic or rubber when driving
my 86 FC NA a bit hard on the freeway.
It is not really a problem but I like to find out whats the cause of this.

My FC does that always when driving a bit harder, but today it was excessive.
I had an Audi behind me going uphill so I floored it and shifted down to 4 th and then to 3 rd hitting about 7000 rpm for a second, then redline.

That being said, a few secs later I could smell it, and it went away later.
But this time it was stronger than ever, I thought my car will start to burn itself down.
I looked in the mirror but there was no smokescreen and also no audi anymore.

My first thoughts were that it has to be somthing related to the exhaust or manifold,
because you can just smell it when running hard.
Also this time the clima was off.
I looked under the hood expecting to find a cable or some rubber tube sticking to the
manifold but I didnt.

I should say that my shop did a repair to the undercoating protection, they
resprayed a few areas under the car. Maybe they got some of that stuff on the
exhaust ?? But I dont think if that will be true that you can smell it in the car going 180 kmh.


Do you have any Ideas what could cause such a behavior ? Is there anything common
which could cause this ? Or has anyone the same problem ?

Best regards
Steven

jjcobm

iTrader: (18)

Its something stuck to the exhaust that when it heats up (under accel.) it starts to burn. I wouldn't be surprised if you have tar or undercoating stuck on the exhaust.

Another thing, sticky brake pads would cause burning smell, if they are constantly rubbing against rotor. Lift wheels and check to see if they spin freely. Also, if you just had a brake change done, they may have forgotten or lost the "springs" that go in the rear brake pads which spreads them apart. Without this spring, the rear pads will constantly rub ever so slightly against the rotor and will smell "burning" depending on the brake pad material.

lonewolfrx

id say check if anything melting onto your exhaust. Had that burning smell on my car for a bit til i saw some rubber n plastic melted onto my exhaust pipe when i did my oil change

StevenL5975

Thanks for the reply,

I dont get it how I can smell the brake pads inside the car while driving.
But certainly a point to consider, I will check that.

Yeah, with the undercoating, I have to say they made a big mess, the entire right side
of the car is covered with undercoating.
My FC is white, but not on the right side, they made it look like gray.
For example, it took me today about 1 hr of work with tar remover to get an area with
about 20 cm² clean from that stuff. (and looks like **** now)
Needless to say I changed the shop.
(They even did not tight up the wheel nuts correctly ...)
And the slotted brake discs are also interchanged (left to right and vice versa)

Judging from this I would not be too surprised to find undercoating on the exhaust.
But can you smell that stuff inside the car during a hard freeway run ??

For rubber or plastic melted to the pipe, where to look for ? are there any tubes going
along the exhaust which can come in contact with it ?


Best regards
Steven

jjcobm

iTrader: (18)

Yes you can smell it coming into the cabin. The shifter area is a giant hole that fumes will come through. Also old trunk/hatch seals will let fumes in, especially when driving fast and the air flow properties recirculate the air back into the car in the rear.

rotary_bünta

iTrader: (3)

this may be a stupid suggestion but is your car lowered? are you tires rubbing?

or

i would check the engine bay for anything and everything that is rubber related. drive around until you smell it again and then pop your hood for closer look. something is either touching something hot or is rubbing, belts maybe?

StevenL5975

Thanks for the reply,

@jjcobm
I replaced all the shifter bushings and boots around there, i dont know how tight they
fit, but maybe not tight enough.
Recently I can hear a rattling noise commong from under the car when the engine is started or stopped.
Maybe a heatshield that made its way loose. As I dont have a carlift I cannot check for myself.

@rotary_bünta
Suspension is still stock, wheels too. I changed the plug wires to racing beat 8mm
silicone ones.
I will check for any rubber related parts on the engine when I get the next occasion.
I recently got a LCD borescope, so I think this will be a great help looking down to the
engine bay, especially drivers side.
There is definetly too much cabling =)

Regards
Steven

jjcobm

iTrader: (18)

If you replaced the boot, then thats that, but if it's something burning under the car, it will still go into the cabin, trust me. The ratteling is most definetly a heat shield. The bolts that hold them on are known to rust and fall apart. If they undercoated your car and "forced" the heatshields out of the way, or they removed them, they could of "forgotten" to secure them.

Your issue i am sure has to do with the undercoating getting on your exhaust. I wouldn't be surprised if its covered in the stuff. Take a look and let us know.

StevenL5975

Yes, I also think that it is related to the undercoating stuff.
Next monday (24th) it will go to a mazda repair shop, getting new trans and diff oil + new battery.

I will ask them to check the exhaust for oversprayed undercoating and have a look
at the heat shields.

Last year I wanted to replace the exhaust with a racing beat one.
I wanted a full replacement (header to muffler) with cats to stay street legal,
but could not find one. (I have the dual setup) Then the whole exhaust thing would
be done. The actual one had been welded a few times and I think it still has a few holes.

Regards
Steven