Improvements in Later Model Year GM 6.5 L Diesels

I was thinking of buying a '98 GMC dually with a 6.5 turbo diesel that has 138,000 miles on it. I was reading your article on the suburban build up and was wondering, did GM improve any of these reliability and power issues on the later year models? Thanks, Chad H.

Flickering Lights and Unintended Downshift in '95 6.5L Diesel Suburban

I hope you can help me out with my ’95 6.5 L diesel Suburban. When least expected, all lights on the vehicle will go dim then bright, flickering up and down. Then the transmission shifts down to 3rd ? gear. If I shut it off and restart, the transmission works fine again, until the flickering happens. I have had it checked out by the dealer who tells me he can find nothing wrong. Any ideas?

Pam, Modesto, CA


6.5 L Diesel Tachometer Reads Higher Than It Should

I think I have a problem with my 6.5 L diesel tachometer. I think it reads higher than it should. It seems to have changed since the alternator was replaced, but I cannot understand how this could have caused any change. Can you help me understand?

6.5 L Diesel Truck Won't Start When Warm

I have a question regarding our 1998 K3500 6.5 diesel truck. I have posed this to many service people, many of whom have made suggestions, none of which have helped. Here is the problem; the truck starts fine and runs well until I shut it off. Then it is difficult or even impossible to restart, unless we leave it sit for four to five hours. When we are traveling, we just cannot stop the engine, unless we are stopping it for 4-5 hours. Service people have already replaced:
  • Computer,
  • Injectors,
  • Batteries,
  • Starter motor,
  • Glow plugs,
  • Glow plug control box,
  • Fuel filter
  • Etc., etc.

Any ideas?

Tom, Austin TX



Bill Heath owns Heath Diesel Power in Ellensburg, Washington. He races at Bonneville in his 6.5L Land Speed Racer whenever he gets the chance.


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