Off Topic, early 90s 1/2 Ton 6.5 diesels

[mogulmasher]

I have been searching around for a beater 4x4 (hopefully a decent K5 or shorty) and have noticed a handful of early 90s 6.5 turbo diesel Tahoes and PUs....and they have been cheap! Just saw a turbo diesel '92 Tahoe on craiglist for $3200.

Not sure if I'm interested in one or not, my thought is that they'd get great milege and would tow light loads (my 3-placed v-nosed enclosed snowmobile trailer) with ease. I know they have a detuned 6.5, but still must have some grunt in a 1/2 ton truck.

So are they junk, or just not diserable????

 

[diesel4me]

not junk!...

While they are no Duramax or Cummins,the 6.5 is a pretty good motor for light duty "trucking"...it's the bigger brother of the 6.2,and some were turboed in the '93 and up models..early turbo ones were not computer controlled,and seem to be more reliable than later models with computers...

Humvees used this motor for awhile,anything that survives army use cant be "junk" really..I would not be scared of buying one,they seem to hold up well if properly maintained..

My brother had a '93 GMC 3/4 ton 4x4 with a 6.5 turbo,and the coveted NV4500 tranny with the real low granny first gear..had it over 10 years,never any major repairs or problems,and it got over 20 mpg ..had well over 100,000 miles on it ,and showed no sign of wear really..I would have bought it if it had not gotten salted underneath,it was getting petty crusty framewise...still,he had no trouble selling it for 3500 bucks,with a fisher plow setup..he upgraded to an '02 3/4 ton extra cab 4x4 with the Duramax and Alison tranny..awesome truck!..(I'll admit his "new" truck made the older one seem like an antique though,as far as ride comfort and power!..)

 

[BKinzey]

The early diesels were 6.2 and naturally aspariated. In 93 GM upgraded the engine to the 6.5 and a turbo. In 95 GM went with a electronic controlled injection pump. In Turbos GM went from a GM-1 to GM-8 they did skip a number or two. I'd be cautious of the early '90s with anything less than a GM-3 turbo on it (pre-93?). Better is the GM-5 and most coveted is the GM-8.

There are all sorts of variations on the engines through the years and an excellent place to learn about them is The dieselplace.com

 

[mogulmasher]

The early diesels were 6.2 and naturally aspariated. In 93 GM upgraded the engine to the 6.5 and a turbo. In 95 GM went with a electronic controlled injection pump. In Turbos GM went from a GM-1 to GM-8 they did skip a number or two. I'd be cautious of the early '90s with anything less than a GM-3 turbo on it (pre-93?). Better is the GM-5 and most coveted is the GM-8.

There are all sorts of variations on the engines through the years and an excellent place to learn about them is The dieselplace.com

Correction on the year, its a '94. So what turbo would that have....would it be one of the good ones?

Weren't there a lot of problems with the electronic injection pump on the 6.5? So as far as a used rig is concerned it would be best to have something with the later turbo, but no electronic injection pump?

Truck has 170k miles, i know diesels can go long way, but must be stuff that needs replacing at that milege?

 

[rjfguitar]

I'd jump all over a nice 6.5TD 2 door tahoe. Good mileage and good power.

The electronic version is fine, there is just a problem with a certain control box (can't remember the name of it) that is problematic with failing in those trucks. IIRC from different 6.5 threads, the main suspected cause of this failing computer doo-bober is heat soak, and there are ways to mount it in cooler spots.

I'd take a 6.5 TD Tahoe with a 4L80E any day over a 350 powered version.

 

[BKinzey]

If it's a '94 it should have a GM-4 Turbo and have a manual injection pump. If it is electronic it will have a black box about the size of a deck of cards on the side of the pump.

The biggest problem with the electronics had to do with heat frying the box. Aftermarket has taken care of that by offering a cooler and wiring extension to move the box to a cooler enviroment.

At around 160,000 miles it is not unusual to need a rebuild on the injection pump. If it's electronic and the PMD (box) is still mounted on the side of the IP you can expect a needed replacement and certainly moving the PMD.

It's highly reccommended that EGT and Boost guages be added to the vehicle as well.

Overall engine cooling can be a concern and in '97 GM added a cooling upgrade. There are a couple of aftermarket solutions to be had here.

If you want more than stock power then an intercooler should be part of an upgrade.

You are never going to compete with a Duramax but the 6.5L Turbo Diesel can be a very reliable and worthy vehicle for what it is.

 

[mogulmasher]

If it's a '94 it should have a GM-4 Turbo and have a manual injection pump. If it is electronic it will have a black box about the size of a deck of cards on the side of the pump.

The biggest problem with the electronics had to do with heat frying the box. Aftermarket has taken care of that by offering a cooler and wiring extension to move the box to a cooler enviroment.

At around 160,000 miles it is not unusual to need a rebuild on the injection pump. If it's electronic and the PMD (box) is still mounted on the side of the IP you can expect a needed replacement and certainly moving the PMD.

It's highly reccommended that EGT and Boost guages be added to the vehicle as well.

Overall engine cooling can be a concern and in '97 GM added a cooling upgrade. There are a couple of aftermarket solutions to be had here.

If you want more than stock power then an intercooler should be part of an upgrade.

You are never going to compete with a Duramax but the 6.5L Turbo Diesel can be a very reliable and worthy vehicle for what it is.

Would adding power to these be a good idea? I thought they had a detuned version of the 6.5 because the light duty frame couldn't withstand the 425-430 ft/lbs torque the 6.5 produced......think these had 380 ft/lbs of torque.

 

[oll' bessy]

i was looking for a 6.5 a while back. biggest things i found out was that the electronic controled ones tend to fry thier PMD (pump mounted driver, also called FSD). it is loctaed right on top of the engine and gets hot so it burns up. there are kits to relocate it and put a heat sink on it so that it wont be a problem. other then that, they seem to be good engines. no D-MAX but a good diesel. there are a few power adders out there for em to. check out http://www.ssdieselsupply.com/index.html

 

[jdemaris]

Would adding power to these be a good idea? I thought they had a detuned version of the 6.5 because the light duty frame couldn't withstand the 425-430 ft/lbs torque the 6.5 produced......think these had 380 ft/lbs of torque.

The main reason for the power-rating is emissions. The heavier the weight class, the more fuel could be pumped into it and still comply. The lowest - 6.5 VIN code P is 155 horse and 275 lb. ft. of torque - used in under 9000 GVRW trucks. The next higher is VIN code F - with 190 horse and 240 torque - used in 9000 to 14,500 GVRWs including some Suburbans. The most powerful - VIN code S was offered - I think - only in 3500 crew-cab trucks and is rated 180 horsepower and 360 lb. ft. of torque.

 

[k204dr]

all you gotta do is change the intake to the non-egr one, and put a gm8 turbo on it with a larger exhaust. makes a nice daily driver.

 

[BKinzey]

Sure! Like anything else A little more power here, some torque, showin' off with a brake stand and "Hey! Look how that 10 bolt axle shot out of the rear"

There are lots of options and choices to make. I've been doing a lot of reading as it's what I'm doing on my project. So a word of caution. I'm telling you what I've read not experienced for the most part

The general consensus here is it's a good basic deal.

Just remember, when you start playing around with it for the vast majority of us it took a little more time and a little more money than we first thought. At least once during the process you might find yourself checking out sniper positions from tall places

 

[rjfguitar]

Would adding power to these be a good idea? I thought they had a detuned version of the 6.5 because the light duty frame couldn't withstand the 425-430 ft/lbs torque the 6.5 produced......think these had 380 ft/lbs of torque.

The frame would be just fine.

You can get different injectors IIRC from BD, and BD also sells a programmer for the electronic version, IIRC of course. I don't follow the 6.5 stuff much.