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Friday, April 9, 2010

Dodge Dakota Serpentine Belt Tensioner

Notice the very slight difference in angle between the arm that holds the pulley and the pin directly to the left of the mounting stud. Not much, maybe 10 or 15 degrees.
About a week ago I was giving John a ride to school in the truck. It started squealing shortly after we left the house. It sounded like a bearing going bad, but it's had squeaking problems before, so I drove on thinking it would stop in a bit. It didn't. It squealed all the way (12 miles) to school and all the way back. I was saying my prayers that it wasn't going to blow up and leave me stranded.

Got home and took a look and the belt is loose. All the pulleys and bearings seem to be in good shape, just the tensioner has lost its' spring. I might have been able to save myself a little trouble if I had only taken the tensioner itself off, but the bolt that holds it in place is obscured by the supporting bracket, and the three bolts that hold the bracket in place are in plain sight.

However one of the these three bolts is behind the dipstick tube, which means taking the tube loose from the alternator, which wasn't too bad, but putting it back in was a real trick. I mean it's in plain sight, but you cannot get your hand in there to put the bolt it. It took some real finagling to get it in the hole.

Tensioner support bracket mounting holes.
Taking the nut off of the tensioner itself might have been slow (it's a long bolt), but I don't think it would have required the dexterity of Houdini to get it back in.

Hooking wrenches together to
get more leverage.
Putting the belt back on required compressing the spring, and these springs are strong. I put the box end of a combination wrench on the bolt holding the pulley on, and then put the loop at the end of the handle of an adjustable wrench over one of the claws. That gave me a lever that was long enough to make it easy to compress the spring. (This is a picture I found of a similar arrangement.) It works in most cases, though if the bolt is really stuck, and you apply enough torque you can bend the claw of the combination wrench.

Update February 2017 replaced missing pictures.


Ole Phat Stu said...

The people who design stuff like that should be forced to do every single maintenance job and then they'd go back to the drawing board!

Chuck Pergiel said...

The guy who designed it would have know not to take the bracket off, just unscrew the one nut holding the tensioner in place. Of course, he also would have known where it was.