Help...Have I purchased a lemon?

[jwb]

Purchased 93 3/4 ton 4x4 Chevrolet,with AT and 3.73 rear differential, 6.5 Turbo Diesel which has mechanical fuel injection pump. I purchased it new August 1993. In 94 Chevrolet went to electronic fuel injection pump. I purchased pickup before retirement, and the way I cared for the pickup I figured it would last a good 25 years or a few hundred thousand miles. Glow plugs and mechanical fuel injection pump failed at 61,000 miles. I now have 73,000 miles on the pickup. I occasianally pull a light 27 ft 5th wheel. It seems to consistently run near the red line (240 degrees) when towing. I do not tow in overdrive, as per owners manual. For the last 5,000 miles it has begun to spew black smoke when towing and when accelerating. The last time I towed the 5th wheel it sooted up the trailer for 12 feet back from the exhaust. I am having trouble getting to the bottom of why it's smoking like it is. I went to the diesel mechanic at the local GM dealer, he adjusted the injector pump timing to specs, and reset the TPS sensor. He said that he does not have much experience with the 93, but agrees it spews black smoke excessively, and doesn't know why. My fuel mileage and oil consumption have remained about the same, I get 10-13 mpg towing the 5th wheel, and when towing it uses 1 qt of oil every 1,000-1,500 miles. Once empty and once towing, in it's life span, it used a qt of oil in 400 miles. Once at 70,000 miles and once at 2,000 miles. I purchased the "6.5 diesel troubleshooting and repair guide" from the Diesel Page, and took it to the GM diesel mechanic. He did not get much help from it on this 93 with the mechanical fuel injection pump. He pulled the service bulletins and found "black smoke after injection pump replacement, #47-63-04", Jan 4, 95. It applies to the 94-95 Turbo. But he checked the gasket placement on my 93 to be sure it was OK. The 8 glow plugs that were put in at 61,000 are part FP#12563554, and the fuel injection pump that was installed at 61,000 is part FP#22860. That's from my records with the GM dealer in Alaska. I would even appreciate Jim Bigley responding to my problem. This pickup has had impeccable care. I have begun to suspect that the 6.5 (or this 6.5) is a lemon. Can anyone out there help me with which way to turn now?

[rjschoolcraft]

First of all, the truck is 12 years old, although the mileage is quite low. I don't think "lemon" is appropriate for something you've owned for that long.

Your black smoke is likely the result of low or no boost pressure. Check your waste gate control and pivot to ensure that all is working as it should. The waste gate pivot bound up on mine once, causing low boost.

It sounds like you need to find a different mechanic who knows about the 6.5 Diesel.

The 6.5 cooling system is known to be inadequate in the earlier models. Read about the Project Truck to learn about cooling system changes that will help your truck significantly.

Furthermore, your temperatures will decrease significantly if you tow in overdrive. GM later removed that stipulation from the owners manual which was a holdover from the earlier overdrive transmissions that weren't capable of towing in OD. The 4L80E is quite capable. I've found that egt and coolant temperatures are much higher when towin in direct with high engine speed as opposed to OD.

[cruzer]

What RJ said!!!
Sounds like minmal to no boost. Lack of boost
can make the engine run hotter. Also Debug the
radiator. Check in to 97 cooling mods and newer fan and clutch. The 6.5 is under powered in comparison to others,but can be made to run.
They're more a dog than a lemon in stk form. A few mods can wake them up. Gauges,larger exhaust and Turbo Master Boost controller.

Use the "search" function at the top of the page.
If there is a problem w/the boost and it is the boost controller you should consider the Turbo Master, but b4 you do anything, GET GAUGES, EGT & boost.

Personally I prefer mechanical injection. Alot of people have had problems w/electronic injection componets.

[N9Phil]

Jwb,

I had a similar problem with my 88 non turbo 6.2 and it ended up being leaking vacuum lines and throttle position sensor. With the bad vacuum, the egr wasn

[cruzer]

there shouldn't be a vacum pump on a 93 6.5td & no EGR on a 3/4ton.

Most likely a boost/turbo problem. Did you check the aircleaner?

[JohnC]

Ditto the air filter. Also change the fuel filter. Never could really figure out why, but there have been cases where black smoke was cured by changing fuel filter. Probably something to do with pump housing pressure.

Do you have a boost gauge? You should. The '93 style boost control leaves a lot to be desires. Heath's turbo master is a big improvement, assuming everything else is good.

[catmandoo]

i'd say with a mechanical pump it's peachy and not a lemon,just can't beat that mechanical pump.

[moondoggie]

Good Day!

What RJ said. From all you wrote, you likely have a very simple problem related to lack of boost from your turbo, & a mechanic that CLEARLY doesn't know anything about 6.5's. :mad:

Black smoke virtually always means insufficient air, which means your turbo ain't turbo'ing, for one reason or another. Hopefully one of the '93 folks will chime in here with more accurate information that I will present. I think you 93 has some sort of spring-loaded device to control boost; vacuum control of boost didn't occur until the 94 models with our esteemed electronically-controlled IP. If this is so, that spring-loaded device has quit, or the arm from it to the wastegate has broken, or the wastegate itself has failed (don't know if this happens at all or very often, I don't think so).

I would avoid pulling anything until you fix the black smoke issue. Unknown to you, your EGT's are probably sky high under these conditions, dramatically reducing the likely lifespan of your engine. :eek:

Get the black smoke issue fixed, then tow in overdrive (if power is adequate), & keep your temp gauge under 220 or so - your truck will last a real long time, IMHO. :D You can do MANY mods to increase the power AND reliability of the 6.5, but you don't have to do any of them, as long as you live within your 6.5's limitations.

Blessings!

[Marty Lau]

JBW;
How much would you want for that '93 Lemon of yours, I might consider making some lemon aide? And where about in New Mexico are you?