Wednesday, January 1, 2014

Surprise Project: How to replace the alternator on a 2004 Hummer H2

This morning I put new struts in the minivan.  While I was out test driving it I stopped for gas at my local shell station.  There was a Hummer H2 there with the hood open, and a very forlorn looking chap sitting next to it.  The car was stuffed with presents, dogs, and kids so I asked if they needed any help.

As it turns out they were coming home from Christmas Vacation in Georgia, on the way to Kentucky.  They'd broken down, and were desperately calling around to find a shop that could tow and fix the car.  It's relevant to mention here that this was at 4:45 in the afternoon on New Year's day in a very small town that doesn't have a red light, much less an auto repair shop.

We talked about what it was doing and it sounded like it was probably the alternator.  The chap's wife said they had found someone to tow it for $500,, but that was just the TOW, not to fix it.  Ouch.

I offered to pull the alternator and take the fellow to get it tested.  They were ecstatic.

Tools required:  3/8" drive socket set, 5/8" wrench, flathead screwdriver, prybar

The replacement was really easy.  Remove a battery cable.  Remove the vanity cover over the intake manifold (1 bolt)(Red Arrow).  Remove the plastic air intake (two worm clamps)(Green Arrows).  Remove the electrical connector and charging cable  on the Alternator.  (One bolt)(Blue Arrows).  Remove two bolts that hold the alternator in place.(Yellow Arrows)  Then pry the alternator up and out.

View from Driver's Side of Engine


Looking down at front of alternator

Passenger's side view of engine
Back side of idler pulley


The fiddly bit was getting to the idler pulley to loosen the serpentine belt.  To do that you had to remove the plastic air intake.  To do THAT you had to get to the two clamps that held it on and you couldn't reach the intake manifold end clamp until you got the plastic manifold cover off.  Annoying.
The MAF sensor insisted on coming out with the air intake too, so I had to undo that electrical connector.  Blarg.  Once you had that big plastic behemoth out of the way the job is easy.  Slip a 5/8" wrench on the big bolt on the front of the idler and lift up.  The belt will slip right off. 

Two more tips:  First, bring something to stand on.  This truck is high.  I'm over six feet and couldn't reach in easily.  Second, when you get the old alternator out you should tap/hammer/squeeze/pry/finagle the little metal sleeves under the alternator a little bit to make room for the new one to fit in.  The bolts squeeze these into place to hold the alternator tightly.  That makes getting the new one in very snug.

The job took less than an hour with another half hour for the run to the parts store.  I only got a few pictures, but the folks were ecstatic to be back on their way.  Hopefully this post will help someone else.  Sadly I neglected to get their names.  Good luck, whoever you guys were.

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