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I have a 95 K3500 6.5 dually with a auto trans. It gets about 14.5 mpg highway driving. It runs about 2500/2600 rpm at 70 mph. My question is, is there a easy way to tell if converter is locking up? I cant seem to feel it lock up. Am I wrong to think the mileage should be better?
Tom
Howdy
In my experience, you are pretty much right on. Both with RPM and MPG.
That truck probably has 4.11 gears, same as all my big trucks with 6.5s. At that RPM it is making great power but REALLY sucks up the fuel, plus you have a pretty good amount of wind drag at that speed.
Optimal MPG will be at around 1800 RPM.
Hope this helps!
Howdy again...
To check for lock-up, either count your RPM shifts: 1-2; 2-3; 3-4; lockup. You can also do this by shifting the gears manually.
Or you should be able un-lock once you are up to speed by lightly pressing on the brake.