I am starting this thread because I am looking for a new diesel suburban. I posted a thread that basically asked this question, plus some other stuff. I also saw another question that is similar and I will add that info here too. Basically, I want this to be a cleaner version of the last post, getting rid of all the other stuff. :rolleyes:


I want this thread to focus on what potential owners should look for in a used GM diesel truck.

So, as experienced owners what would you look for in a truck?

I will start by copying what was said in my original question and the answers I received. Thank you guybb, knkreb, and turbine doc, for helping me.

Make sure the brakes are good. It can cost you over a thousand just for parts if not


At startup,- a puff of white smoke may be expected, but not a smoke screen. On the road, if you see a puff of black smoke, okay. Long periods of smoke of any color is unusual, and indicates an issue.

SES Light (Service Engine Light) in a 96+ vehicle will rat out about hundreds of different things. It will also do that for earlier vehicles. This is how I was "had" with mine. I have a master battery switch. It was turned off after each trip at the dealer, and cleared any codes - which covered up the injection pump that was almost dead.

Turbo, you can hear mostly. Not totally a great test, but one that would indicate if the turbine is spooling.

Oil, will almost always be black. The only way you can tell with oil is send it off for an analysis. That's just the nature of a diesel.

At idle, pull off the oil fill and see if air is blowing out. That could indicate some serious blow-by and other issues.

Crawl under the truck and check for oil leaks on the front and rear diffs and at the driveshaft where it comes out of the tranny. When you are at it, check for engine oil leaking from the plastic panel on the front under the engine. The plastic panel covers oil lines going to an oil cooler in front of the radiator; these lines are infamous for leaking.

Another thread with similar question.

Hey guys,

I was wondering if anyone has any tricks/tips on what to look for in a used 6.5 TD. The truck I am looking at is a 96 1500 w/280 000 kms.

I have heard of the 'bubbles in an open rad indicate a blown head gasket trick'....what else is out there?

I'd look at how hard it is to start cold, how much oil vapor does it put out once fully warm, does the radiator hose get hard with pressure? any oil/tranny drips? I'm not a fan of the S engine G'luck with that.

Another consideration would be: what are you using it for? If you are using it to pull at 30ft 5th wheel camper, or just a daily driver to work? Just for weekend fun, work truck, or occasional trips?

Towing, you'd look at rear gearing, if it's an "HD" truck maybe, and suspension needs. For a daily driver without all of that, you may want some lighter suspension. If you are buying because you would like better MPG's, look at rear gearing.

Many different variables play into this whole equation, let alone, is it a worthy truck to purchase in given condition. Giving the keys to dear wife with an engine with 400,000+ miles on it, may be lookin' a little bit risky . . . . . . sometime, you might have to buy her some roses after tippin' the tow truck driver :)