Did my DMax fan/vac pump delete/harmonic replacement today. With my CS144 alt, my belt length is now 101. It was T I G H T getting it on there. Previous belt with vac pump was 102.5.
I have seen different belts required for different rigs because ac compressor size, location, or alternator difference. If you can swap belt in parts store parking lot is easier to me.
Just install belt and look at tensioner indicator.
The rectangle (between yellow arrows) is good. The lines by the blue arrow indicates belt is stretching too much and needs replaced asap. Too tar the other side would be too tight.
Where the marker is in the picture is EXACTLY perfect new belt.
@Will L. ya know what's crazy? on my truck, I can take the belt off and when re-installing it the marks are sitting right were you pic shows until I start it up. even with a new belt it does the same thing where as soon as it cranks up the indicator moves to the warning mark and stays there!
Over time the belt stretches. Eventually the spring in the tensioner gives and wont pull it as tight even with stretching belt it will “read” ok. Then the belt starts squealing. People chase a hundred things- eventually they guess enough parts and get it figured. Some only replace the pulley of the tensioner and think they ruled out that as a problem.
I think I had to use a 101.5 as well. Different guys have different results, mine was longer than a lot of other guys had to use but the shorter ones were too short.