Is carbon buildup on the exterior of catalytic converter normal?



Mine is looking like this. I have no idea how long it has been looking this way, since yesterday was the first time I decided to pay close attention to this.

 

Is there an oil leak along the back of the valve cover?
Is oil being sucked into the throttle body from the valve cover?

 

If you mean that oil is leaking down the exhaust from the engine valve cover and its is getting burned there, then no. I checked the back of the engine where exhaust is connected and there are no leaks.

There is that small tiny hole on the catalytic converter that I am suspecting to be causing this mess. The hole that is clearly visible in the very back of the catalytic converter in the picture.

I'll clean this mess up and monitor the source of this carbon build up.

 

I would guess it's carbon deposits inside the exhaust that are being washed to the outside by moisture. All exhaust fumes will contain some water or moisture. Yours just seems to have picked that weep hole to make it's exit from.

 

The catalyst turn CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O.

I left the first 2 reactions out because the important part is the xCO2 and H2O in this discussion. (carbon and water). Usually exits at the tailpipe, I don't think catalytic converters have weep holes, mufflers do.

That picture looks more like a muffler to me. My catalytic converter has a smooth skin.

Muffler marked M, CatCon marked CC.

 

You are correct. That is a muffler Don. I just didn't look closely at the pic or I would have noticed the rear suspension spring in the background.
(Muffler is at the rear of the car. Cat is up by the engine. )