Cadillac Repair: 2004 Escalade ESV - rotten egg smell under the hood, battery just died, weird clicking sounds all just today!, automotive forensic expert, auto theft claims master


Question
Hi Rob,
My mother and I went to the beach today and on the way there, we noticed the car smelled like rotten eggs or something similar.  It seemed to be coming through the vents instead of from inside the cab interior. We just got home and we pulled into our driveway like normal and my mom turned the car off like normal. She told me we needed to search the cab for what could be causing that weird smell, and before she got out of the car, she wanted to turn the car back on to roll the windows down to air the cab out.  Well, the car wouldn't turn on...nothing happened.  I asked her to check to make sure it was in Park and she said it was.  We had just driven home about 50 miles, so it was weird for the battery to be dead like this.  I popped the hood and I can smell that rotten egg smell coming from the engine area and when I turn the key on, trying to start the car, the engine light flashes quickly (almost like a pulsing) and nothing else happens besides some faint clicks coming from the center of the engine (not the battery area).  I have NO idea what is going on.  I remember yesterday, I started the car to leave and I heard a fairly loud abnoxious sound coming from under the hood...it seemed to be coming from somewhere near the driver's area...like near the base of the drivers side windshield.  I muted the radio to listen to the noise and just then, it went away.  So, I never got a clear listen to really figure out what the sound was.I regret not investigating that noise further...I honestly just forgot about it and figured it was nothing serious since it seemed to work itself out.  
Maybe that had something to do with today's problem?  

The car is a 2004 Escalade ESV and it has maybe 90,000 miles or so. It has been taken care of very well and driven fairly lightly.  My mom wants to sell it ASAP and she was always worried she would not sell it in time before things started failing one after another.  :(  Maybe this is what's going on.  

If you can give me any advice, I would be very grateful.  I am a 37 year old woman without a lot of knowledge regarding engines,systems,  parts and such. I am pretty stranded but I really want to help my mother.

Answer
Hi, thanks for your question. Without being there it is very difficult to diagnose your problem, but I have ideas as to what is going on.

There are only 2 places you can get that smell the catalytic converter or the battery. That is it. I doubt if this is a cat problem with the smell located under the good.
You stated you had issues starting and battery was dead.
It is possible the battery is now junk. I simply do not know, but it sounds like it was cooking. What causes this are one of two things. An alternator over charging above 14.2 volts or a bad battery negative cable ground to the frame.
When the battery over charges acid bubbles out and you will smell sulfuric acid which accounts for the rotten egg smell. Sometimes this condition can cause the battery to explode!
I suggest you have a service tech not from a dealer, remove and remount the ground first. If that does not work, the alternator output has to be checked. I believe one of these solutions will fix your problem.

Good luck and get back to me.

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