Went to test drive a '95 K3500 Ext Cab 4x4, 6.5 that I've had my eye on. Had the VIN run and nothing on it other than 2 pumps replaced within a month, about 4yrs ago.
For the most part the truck was as advertised, though it was in need of exhaust work and front rotors. During the test drive I took the liberty of 'standing on it' from 55mph in OD. Trans shifted down, RPMs increased but there was absolutely no increase in MPH. When I let up on the throttle, RPMS fell, and trans shifted up. A gradual application of throttle would increse MPH. Am I looking at a 4L80E in need of some attendtion and if so, what - rebuild or reman? Thanks.

Trans shifted down, RPMs increased but there was absolutely no increase in MPH.
Remember you were driving a 6.5L http://www.dieselplace.com/forum/images/smilies/redface.gif

Power was never it's strong point!

Seriously though, was it slipping then?

What was the 1-2 and 2-3 shift like?

Remember you were driving a 6.5L http://www.dieselplace.com/forum/images/smilies/redface.gif

Power was never it's strong point!

I agree there. I have driven many that don't go any faster when kicked down into 3rd. If it is slipping under that condition there should be a burnt smell to the fluid. #rd gear uses the direct clutch, so does reverse. Manually shift from 2nd to third a bunch of times at different throttle positions and see if the shift is consistent. Also make sure reverse is strong.

A clogged fuel filter could cause this. But in general, these engines allowed more boost at lower RPM's, so when you downshifted, you got more RPM's but way less boost and torque.

To tell you the truth, unless it has real low mileage, or is real nice, I'd skip a used 6.5.

Just too many problems to encounter with that engine. It was a good year for the truck ('95+) but I'd buy a big block over the diesel in a heartbeat.

Unless your prepared to fix and tinker to keep running (and not reliably running), and are content with the lackluster performance, I'd suggest you save your money and look for a good used 2001 with the DMAX.

Only good point about a '95 is that its easily chippable.

Remember you were driving a 6.5L http://www.dieselplace.com/forum/images/smilies/redface.gif

Power was never it's strong point!

Seriously though, was it slipping then?

What was the 1-2 and 2-3 shift like?
The 1-2 and 2-3 shifts where noticable, byt smooth. No heavy 'hammering' or 'thunks'. You knew the trans had shifted.

Also of note, as Tom hinted at, was the fact that when at 55 hard on the throttle and downshifted, there was a distinct 'balking', almost backfiring of the motor, much like it was starving for fuel. One of the things I noted on this truck was that it had an aftermarket FSD - somewhere along the line the previous owner(s) had had IP probs beyond just the pump itself or they wised up after replacing 2 pumps.

Lastly, I do take note of Tom's reference to a big block gasser and have given it consideration. My need for the power/torgue is weekend towing of a 20ft tandem gooseneck with a skid steer and attachments, or D3 Cat crawler tractor for my sideline job. It's not like I would be driving it daily. For that the Jetta TDI is the ticket (50mpg).