My 6.5 threw it serpentine belt. Water pump, alternator, idler, AC all turn freely. to the passenger side , left of the water pump and crankshaft is a pulley I can't identify. Looks like a vacuum pump. Anybody know what it is? It does not turn more than 1/8 rotation.
Greetings,
It a vacuum pump. Unfortunately I can't remember if it should turn freely or not, but I don't think it will. The center shaft is connected to a cam lob which moves a piston to pull a vacuum. There is supposed to be a certain amount of synthetic oil inside the cam case and it is possible for a pump to fail (I had to replace mine on my former '95 C1500 with the 6.5L TD)
That's about all I can offer right now - Jonathan
The pump should turn by hand, but with alternating difficulty as the lobe compresses the spring for the diaphragm. Go to your local parts store and ask to check out a replacement pump for comparison.
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