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GM Diesels Suck
I want to buy a new one ton diesel but my 3/4 GMC
deisel sucks. Any recomodatios. I have heard a
rumble here and there about a full CAT deisel in GM
truck. Someone please help me in my choice
deisel sucks. Any recomodatios. I have heard a
rumble here and there about a full CAT deisel in GM
truck. Someone please help me in my choice
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I have heard those rumbles from GM fans for 2 years now. My father was an Operating Engineer on D-9 Cats all my childhood and I would consider buying a GM product if it were Cat powered. However I have been listening to the same rumors about the Cat powerplants in GM's for 2 years with no sign that it's about to come to pass.
That is why I am going to go ahead with a purchase of the Ford '99 F-350 with the proven International/Navistar turbo diesel. Stump pulling power and a long life.
If and when a Cat powerplant makes it into a light truck I will look at the brand it goes into.
Does anyone else have more recent information on the Cat/GM rumours?
I actually work for GM, and alot of people in the higher up positions(trainer and teachers) have been mentioning the CAT. but if I don't hear more good news about it, Hello 99 F-350 xtended cab dually diesel.
Maybe bigfur coming to work in a brand new Ford SD will let GM know that they couldn't make a suitable heavy duty truck... nothing lets a manufacturer know their products are weak like their employees buying the competition's products. Kinda like a Gateway employee bringing his Mac to work...
I'm just like you. I like style and a whole s#$t laod of power. GM has the absolute weakest deisel on the market. I like working for them but I am not ever going to buy 6.5 deisel unless it was a deal i couldn't pass up(i havent come upon one yet).
Thanks for the encouragement
BigFur
I have heard and read(in town hall) many horror stories of GM deisels. There are people on their third or fourth engine by a hundred grand. Currently tey are experimenting with Isuzu and CAT engines, but havent heard anything beyond that.
The big knock on the GM diesels is lack of power. Until this past year, they hadn't even produced 400 lb-ft of torque WITH a turbo. Everyone is aware of the Dodge/Cummins and Ford/Navistar battle, and the heavy duty truck market shops there because they get power and good economy in a strong truck. The 6.5 needs aftermarket upgrades to match the power, and suffers in economy because you have to keep your foot in it more than the other diesels.
Don't expect the next GM trucks to be successful even with the Isuzu diesels. You will hear "[non-permissible content removed] engine" almost immediately (as bad as that is to say), and the fear of expensive replacement parts (from the experiences with Japanese cars) will also drive people away.
wait to you have to fix any diesel. its going to be expensive as hell whether it was produced in Japan, detroit, hawaii, whatever...
GM diesels were designed at the lower horsepowers for effieciency reasons. i don't know how much yall know about them. the 6.5 turbo was a strong engine up till '94. it gave almost identical performance to ford's turbo 7.3 (pre powerstroke).
My father bought a ton and a half chevy diesel in '94. that year, they change their injection system to completely computerized. there wasn't even a throttle cable, just a wire running from the accelerator to the fuel pump. the diesel was smokeless. you cannot make it smoke, no matter how hard you clutch it or put your foot into it. the engine met emission standards for year 2000 something.
they had lots of software problems. my dads truck would die every now and then when he was slowing down to a stop and clutched it. not fun when your work truck weighs 14,000 empty. a GM engineer would come to the dealership with different stuff, because in '94, the really had no clue what was wrong with these engines. they tried several different computer chips. one of them they tried had awesome power. that motor would smoke like peace pipe, but would it run! they thought pumping up the fuel would keep the engine from dying. it did. but the chip also had a flaw that made injectors miss at idle, and the truck literally shook back and forth it was so bad (at idle).
they finally found the software glitch and the truck has been flawless ever since. but it does not run like a powerstroke, and it gets only moderate mileage, but 12 mpg isn't bad in 14000#. another company with superduty powerstrokes in similar trucks never got better than 7 mpg.
when a diesel smokes, there is more fuel burning than air will allow, or there is too much air. the black smoke you see is unburned fuel. the way GM did this is with an airgate. they carefully monitored the air fuel ratio at every instance, and would actually dump air out of the turbo line, if the mixture was not right. or the computer would cut back fuel, even if you had the accelerator pushed, that way--no smoke. the result: an engine that wouldn't go when you wanted to. basically that diesel grunt that everyone loves, happens you're at low rpms, you step into it, and some black smoke starts coming out the back as you accelerate.
that was longer than i anticipated, but you basically have the story behind the 6.5 GM.
I really have to floor my Cummins to get smoke. It *does* have a cat-con, but the new 24 valve doesn't use one, not even in California.
The 6.2 was so weak power and torque wise, and the 6.5 was viewed as a turbo "just to have a turbo". Until the "Powerstroke" version of the Navistar, no one could touch the low-end torque of the Cummins, and that spoiled a lot of people for what a diesel pickup should be. The 6.5 is finally over 200 horsepower; the Cummins and the Nav have been there for years, and the Nav has raised the torque benchmark to 500 lb-ft (which the Cummins will match when Dodge releases its 6 speed next winter).
As you mentioned, the 6.2/6.5 was designed to be as gasoline-like as possible in terms of drivability, but GM has since learned, you need the strength as well.
I've been thinking of this almost since the topic was started. I'm also thinking back to the late '70s and early '80s.
Perhaps the three key words are the topic title and that they are just plain fact.
I dun-no,
Rich
I'm not an apologist for GM diesels, but there is one in my garage. Taken as a whole package I like it and it's been reliable. It's not a Powerstroke, nor is it a Cummins, but I think 430 ft-lbs, 4.10 gears, and a 4L80 is enough to tow anything.
You're partially correct about the Cummins forcing the competition to improve. The other half of the equation is the nasty four letter "S" word. The main reason for the electronic controls on my '99 PS is emissions!
There is one thing rather interesting about the '99 diesel. The oil doesn't get junked up nearly as quickly as my old '92 7.3 L. I changed the oil in the '99 at about 2500 miles. It still looked like honey. In the '92 it would take about 1000 miles to turn black with carbon. Granted there are four more quarts, but still......
Rich
1983-87: 6.9L, 170hp, 307 lb-ft
1988-92: 7.3L, 185hp, 345 lb-ft
1993: 7.3L, 185hp, 360 lb-ft
1994: 7.3L(non-turbo), 190hp, 385 lb-ft
A question to Ford guys: How much more power is in the Powerstroke? I seem to remember one poster mentioning 600ft-lbs. Obviously, there's more capacity in the Cummins engine.
I ask because the GM 6.5 TD is basically tapped-out right now @ 430-440 lb-ft. As I understand it, the engine's comp. ratio is too high for more turbo pressure without detonation. So, GM's turning to Isuzu for their next diesel. Should be interesting.
Also, why aren't diesel engine prices coming down? It seems to me that diesel engines are becoming more popular, and this should mean that manufacturers can spread-out costs more effectively, reducing unit price. However, the opposite is happening. Any ideas?
The '99 PS 7.3L in my F-250 accelerates like a smaller gasoline (non V-10) engine would. Very impressive but not of much use at the stop light drag races.
In comparison:
The '99 PS 7.3L is rather quick and snappy;
The '92 7.3L (non turbo) was acceptable;
The '86 6.9L couldn't get out of it's own way;
all three had a 3.73 rear end. Only the '86 was non LS.
The '86 went through the Eisenhower tunnel on I70 at about 48-50 MPH while flat towing a Datsun 310 and carrying three adults with luggage. (For those of you who aren't aware, that's about 11,000 feet above sea level. A good example of torque too.) I was driving by the color of the exhaust. Clear, more throttle; black, less throttle.
In all three trucks, I've never been happer with the drivability (Is there such a word?) of the diesel engines.
There is no way an average mechanic can go through a diesel engine all by himself, even older ones, like 80's model engines. fuel pumps on diesels must be sent to specialty shops that have special tools and test equipment built specifically for diesels. those pumps have incredibly tight tolerances, small gaps, special screens (interior filters that are so fine, water cannot pass thru), and other intricacies. your cheapest rebuild of a simple fuel pump in the late 80's early 90's was in the $300 range.
then there are injectors on diesels. there are only a few places in the country that actually work on injectors, and those are usually the producers. most of the time, you don't work on an injector; you buy a rebuilt set, and give yours to the dealer, and he sends them back to the factory in Timbuktu.
turbos are extremely expensive, and are only worked on, built, or fixed in specialty shops. turbos spin at such incredibly high rpms, they have very specific bearing tolerances, and lubrication requirements, as well as high tech metals used for material, so they can withstand the heat.
now, within the last 5 years, the diesels have become computerized. take all the crap i mentioned above, and throw in complicated fuel injection software that only a handful of engineers in the country actually understand. they only tell the servicemen how to fix it or reprogram it.
if you thought buying a diesel is expensive, you better sit down when it comes time to fix it. everyone says diesels last longer than gas engines, but truth is, over a period of 200,000 miles, the only thing that you really have to replace (given good maintenance) is distributor, plugs, wires---ignition stuff. fuel pumps on these new computerized diesels today rarely make over 120k-150k at the most. that eats up about $1000. then you have injectors to go wrong, head gaskets more prone to blow. i can buy a lot of caps and rotors for that money.
I was just saying how ironic it is that diesels these days are so complicated, since when they are conceptually simpler (no ignition system). I'm sorry if I touched a nerve.
I know I'm asking lots of questions here, but diesels interest me a lot, not just practically (towing power) but conceptually (efficiency, special concerns). This conference has been a great help to me.
http://www.auto.com/industry/qgm9.htm
6.6L V8 direct-injection turbo