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Discussion Starter #1
Hello all,
I am thinking about purchasing a 98 GMC Z71 4X4 with the 6.5TB. I was at a gas station the other night and a guy pulls up in one. I have never herd of the Z71 with a diesel engine, anyway I talked to the guy for a while and he seemed very pleased the engine and the Truck. I might pull a tractor or bobcat once and a while, but would mainly be driving back and forth to work and to hunt on. I have been in a market for a diesel but couldnt see spending the $ for the newer Duramax when all Iam going to do is put in the woods and mud. I have found a 98 GMC with the 6.5TB and would like to here some re-views on how engine hold-ups, what type of gas milage, etc... The truck has 113,000 miles on it, is that a concern?? Thanks in advance!!

Winston
 

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Well i have a 1997 Suburban just turned 171000 miles. It gets 15.5 mpg in town 19mpg on hi way.The most i pull with it is a car trailer with car. Just put in new glow plugs. no major problems
 

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Winston,

Welcome to the 'Place first. Second, at about 100K miles there are some things that you will want to do to restore performance/mileage:

1. Replace Injectors. The service life on injectors is 100K miles, but some say it should be less.

2. Replace glow plugs. If they are original, a new set will help with starting.

3. When time allows, replace the timing set. Again, a service life of 100K miles, and replacing it will restore injection timing. I did this at 118K on my truck and it was a world of difference.

4. Spend some time reading the stickies at the top of the 6.5 forum. It is one of the best collections of 6.5 info you can find for free.

5. Inspect the harmonic balancer and drive pulley, they have rubber inserts that can swell and deteriorate over time and may need replacing.

As to your question of mileage, it depends on loading, driver style, fuel, rear end ratio and phases of the moon :D.

You will find that most of us 6.5ers are very happy with our trucks. Good luck in your decision.
 

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The 6.5 Z71 package is only found in 1500 series trucks....I have one....
 

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Discussion Starter #6
Thanks

Thanks for the input. I have found this website to be most helpful!! I have pretty much found answers to the majority of my Q's. Yes this is a 1500 Z71 6.5TB.

Thanks
Winston
 

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Winston,

I have the exact truck that you are looking at (see my sig and garage for details).
I bought it in 2004 and left it pretty much stock, except for K&N air filter and cheap boost gauge until this past fall.

I ran into the usual problems with the lift pump which lead to the PMD/FSD needing to be replaced. Since then I've started modifying it quite a bit with gauges, exhausts, new injectors and glow plugs, reflashed computer is on order, new high capacity tranny pan is just waiting for the nicer weather before I can install it. I have some plans for some cooling mods (HD Fan Clutch) and who knows what else.

The 1500 is the "S" engine (you'll read about "S" and "F" engines a lot). It means

it has all the emmissions junk on it (EGR and MAF) . My re-flash is going to take car of that.

The bottom line is I'm happy with my truck. I would see if you can get the VIN number and get a history run on it so you can see what has been replaced under warranty etc.

One thing you can be sure of. If you buy the truck and you're mechanically inclined, all the help you will ever need to fix something can be found on this site.

Good luck with your purchase. If you have any specific questions about the 98, let me know and I'll do my best to answer them for you.

Dave
 

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Another good thing you have is one year and 7,000 miles left on the extended Injection Pump Warranty from GM. This will save you about $1,000.00.
 
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