Question: My 95 GMC 6.5 TD 1500 cranks slow. It will start when cold even though it is cranking slow. When it is hot, it seems to crank slower. After using the A/C on my way home, about 1 hour drive I had to cycle the glow plugs twice to get it to start after stopping for some parts. The Ampmeter guage reads lower with the A/C on than with it off even at highway speed. (belt slipping when A/C is used due to increase torque on belt?)


The engine has been rebuilt 1 year ago, (very reputable shop) The alternator has been replaced in the last year, and newer looking batteries are installed (age unknown). I have read that the minimum crank speed for the 6.5 when cold is 100 RPM and 160 when hot.


I will tear down the starter this weekend as my brother has had a similar problem with his 6.5TD and found the starter brushes at fault.


Thanks for replies in advance.

You may have a weak contact at the battery cables. A weak contact means an increased resistance between the battery outlets and the cabling. Resistance tends to be higher at higher temps. So, check the connectors that connect the cables to the batteries.

I just put a rebuild with a lifetime warranty on mine for $275.
It wouldn't crank fast enough to start the truck anymore.
I took it to test and could hear and feel(heat) the difference.

Pulled off the starter last night to check the brushes. Of the 4 brushes, 1 was loose with signs of shorting, and the opposite side was worn almost to nothing. The other 2 could have been re-used. Re-tightened everything and re-installed starter. Starts like a dream! The whole process took about 1.5 hours cost was $10.00 (Canadian) for the brushes. I have changed many chevy starters and this is a very well made and easy to work on model. The hardest part is re-installing with the heat shield. Thanks for the replies.. Dan