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Monday, May 14, 2012


So... As I rolled up to the gate for work on Thursday night and rolled the window down to use the gate key, I heard a funny squeak from under the hood of the truck.

"I'll have to check that out this weekend", I thought to myself as I parked the truck and went inside to relieve the other crew.  It didn't quite turn out that way.

On the way home, I heard the squeak again as I keyed out.  Then about 15 miles from home, hot air stopped coming out of the vent, the battery light came on, and it got really difficult to steer the truck.  I knew then that the serpentine belt had come off the engine.  Thats what drives the water pump, power steering pump and alternator. 

It also became nearly impossible to stop the truck, because there is a vacuum pump that helps run the brake booster.  The truck is a turbo diesel, so unlike a non-turbo engine, the intake manifold is not always under a vacuum.  Thus the need for a separate vacuum pump to assist the brake booster.

It was such a cold morning (28 degrees F) that I nearly made it home before the engine got too hot to continue.  It only took about 10 minutes wait with the hood up to cool the engine before I was able to complete the journey home.

When I got home, I got under the hood and a pulley was sitting on the engine.  It came from the vacuum pump.  Apparently the bearing had seized, and the shaft had dug into it, and eventually the shaft had tapered like a pencil until the pulley had snapped off!

It's kind of a cute pump with an eccentric cam on the rear side that pushes a plunger, which in turn moves a diaphragm up and down.  The diaphragm forces open and closed a one-way valve to pull air out of the brake system.  Kinda clever and Rube Goldberg.  I like it!

I spent most of Friday in town getting parts and repairing the truck.  It had been hard to start all winter and I decided to correct that issue as well.  So I replaced both batteries, the glow plug relay, the belt and the vacuum pump.  Now it starts perfectly in the cold and all the auxiliaries work.   Just cost me a day and $600.  Ouch to both.

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