1998 6.5 2Dr Tahoe

[618 Syndicate]

Don't listen to the diesel bashers. The 6.2/6.5 diesels were great motors. Built for economy not for power. I have owned one 6.2l and two 6.5l trucks. All three had 4:10 gearing, for pulling power. The last pick up, I had for many years. Pulled a big camp trailer all over with it. Empty and a mix of highway and city, always 19.8-9mpg. Pulling the 8000 pound fifth wheel, 15.6mpg.

Key to reliance is like everything, maintenance. I switched to full synthetic oils and gained mpg and reliability. A big help with the injectors, is adding about 1 ounce of 2 stroke oil per gallon of fuel. Helps to lubricate the injectors and gives a mpg gain of 1-3 mpg. Cleaning the "Cooling Stack" (radiator, oil cooler, trans cooler and condenser) is key to keeping everything cool. Cleaning the ground straps once a year.

The only real issues that need to be addressed in the factory set up, is the Pump Mounted Driver (PMD), a set of resistors that were mounted to the injection pump to keep cool, but didn't. Replace and move to the openings in the front bumper.

The oil cooler lines. The GM "snap fit" lines give out and will drain the oil pretty quickly, killing the engine.
The factory waste gate control is vacuum and the lines get brittle and break. I replaced the factory system with a mechanical system and never looked back.

I had other things I did to mine due to pulling a trailer. Gauges (Boost, EGT and trans temp). 5" exhaust and 4" air intake. Water injection to cool the air charge going into the engine. I added a programmed chip into the ECM to go from stock 120hp to 415hp at the fly wheel.

I hated to get rid of it but two kids and three dogs in an extended cab pick up just didn't work. Sold the pick up and fifth wheel and got a Suburban and bumper pull camp trailer. Best mileage I got in the Burb was 18mpg empty and most of the time I saw between 12 and 14. Where I live, gas is pretty bad. Most I have seen in Oregon is 8mpg. Sold the Burb and picked up a 2004 Crew Cab Long Bed Dually with the 6.6l Duramax. But I now pull a 15,000 pound boat. A 33' camper on the water.

No diesel bashing here. Plenty of 6.5 bashing as a previous owner of 2. As I said, they have their place, and as a light duty diesel that doesn't tow fast or heavy and gets decent economy, they can live.
They cannot do what a modern HD diesel does, if you ask them to they will break.

 

[DDTurbo]

We love our 94 K2500 6.5T powered Suburban.
If that Tahoe was right and near I would own it too!
Great mileage and decnt power for the fuel it uses.
Twice drove around the entirity of Lake Erie and didn't stop for fuel.

 

[8Bucksagallon]

Hi all thank you for your replies. Sorry ive been asleep, been travelling. Went to see Truck, and its all there. Needs a little in the cosmetic department, but nothing a long weekend wouldn't solve. Mechanically, Lift pump was U/S, so hard start, drove ok, but noisy, appreciate its a diesel! Owner is a little too proud of it, and I think it's overpriced but he knows I am serious and will think about it. No tow bar, and the interior looks like no one ever sat in the back. I will keep the thread updated. Thanks again all.

 

[GM Guy]

Make sure its getting up to at least 160 degrees and TCC is locking.

The loud engine part makes me wonder if the ECM feed Coolant Temperature sensor (in the thermostat housing) is bad and the ECM thinks its -40 degrees out and has the timing advanced quite a bit. If this sensor is bad, TCC wont lock.

OR

Someone replaced the injection pump and didnt dial it in with a Tech 2 scan tool, timing could be way off.


Main concern is blowby, oil cooler lines leaking, and bad harmonic balancer and damper pulley.

If you do get it, fight the urge to save money buying cheap parts. The 6.5L is especially sensitive to this.

If you use top shelf parts and dont flog on it, youll love it.

Leroydiesel.com and quadstartuning.com, GM OEM grade on rock auto for the rest.

Being a 98 it wont really need anything "upgraded" however if the lines are leaking go with the Leroy lines, if the harmonic balancer is bad go with a Fluidampr.
For the lift pump, ordera AC Delco EP158 off rock auto (1993 C3500) . if they dont have a delco, look for a year 2000 C3500 spec lift pump. almost as good as the 158, better than the 98.

If the vac system is intact, and your country test emissions, you can "ghost delete" the Egr with a 2500HD/3500 "f Code" lower intake, and leave everything else factory. this works on older S code motors without a MAF, but a 98 will be new enough to have a MAF sensor, so you might have to have it tuned if it trips the CEL. Quadstar will be the one to do that.