GM Tops dependability list
Post Fiend
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From: Damascus-Boring, Ore
Originally Posted by 1956MarkII
Should I now list all of GM's incredibly stupid mistakes over the years? No, because: 1) I'm not taking your bait, and 2) I don't have the time and FTE doesn't have the bandwidth.
One comment that did make sense, though, from an engineer that worked for Toyota a decade ago. His contention about the reliability of the US makes had to do with their retirement policies. In the last spate of downsizing, all the senior people were launched with golden parachutes and early retirements. That left the younger people, who didn't have 30 years experience behind them to know what worked and what didn't. He went on to say that whenever Detroit downsized, it was always the senior people that got launched- be it marketing, engineering, production. Sooo...in spite of all the years experience, Detroit was always having to re-learn the industry.
Post Fiend
Joined: Jun 2001
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From: Running Springs CA
BigF350,
The only source of metal fatigue in a cylinder head is thermal cycles. Ive seen cast iron heads full of cracks. Cast iron is brittle, the metallic equivalent of glass, 18ksi yield and ultimate. Aluminum has a little "give" to it. That is why you can have a cast aluminum wheel, but not a cast iron one.
The main reason almost all new engines use aluminum head castings is not just weight, it is heat transfer. Iron does not conduct heat to the coolant nearly as well as aluminum.
Jim
The only source of metal fatigue in a cylinder head is thermal cycles. Ive seen cast iron heads full of cracks. Cast iron is brittle, the metallic equivalent of glass, 18ksi yield and ultimate. Aluminum has a little "give" to it. That is why you can have a cast aluminum wheel, but not a cast iron one.
The main reason almost all new engines use aluminum head castings is not just weight, it is heat transfer. Iron does not conduct heat to the coolant nearly as well as aluminum.
Jim
Postmaster
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From: Marion, VA
Originally Posted by tmyers
I get tired of hearing the aluminum head on iron block non-problem or even the imagined aluminum head on aluminum block. Almost all engine from any of the manufactures are now running this config. We are no longer in the days of the Vega. Can they screw it up, yes but we don't see it much anymore.
The problem is not the aluminum head on iron blocks but the implementation of it. Proper sealing materials, proper head bolt placement, proper torque and correct coolants have resolved most of the problems but a few still come up (like the early quad 4) and keep some people afraid of them.
FTE Leadership Emeritus
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From: Melbourne, Aus
Originally Posted by jimandmandy
BigF350,
The only source of metal fatigue in a cylinder head is thermal cycles. Ive seen cast iron heads full of cracks. Cast iron is brittle, the metallic equivalent of glass, 18ksi yield and ultimate. Aluminum has a little "give" to it. That is why you can have a cast aluminum wheel, but not a cast iron one.
The main reason almost all new engines use aluminum head castings is not just weight, it is heat transfer. Iron does not conduct heat to the coolant nearly as well as aluminum.
Jim
The only source of metal fatigue in a cylinder head is thermal cycles. Ive seen cast iron heads full of cracks. Cast iron is brittle, the metallic equivalent of glass, 18ksi yield and ultimate. Aluminum has a little "give" to it. That is why you can have a cast aluminum wheel, but not a cast iron one.
The main reason almost all new engines use aluminum head castings is not just weight, it is heat transfer. Iron does not conduct heat to the coolant nearly as well as aluminum.
Jim
I also have seen cast iron eads full of cracks.
However, just because it is brittle, doesn't mean it isn't strong.
If an Aluminium yields, a head warps. Just as undesirable as cracking IMO.
The main reason you have a cast aluminium wheel and not a cast steel one is more due to weight (although, cast steel would never be used, for the reasons you mentioned.)
If you ask GM's (or Isuzu's for that matter) engineers, I would imagine few of them would mention Heat conductivity as their top reason for changing to aluminium heads.
Reason being, the cast iron cylinder heads can reasonably transfer the heat in a combustion process, yes aluminium is better, but cast iron isn't that bad that it can't be used.
The main reason would be the weight savings - the heavy nose it the big reason pickups handle so badly (lead tipped arrow anyone?) - what GM have been targeting recently is to make a pickup handle/ride more like a car.
To do this, partly what they have to do, is to remove weight over the front axle.
Hence your aluminium cylinder heads.
And I believe a BMW M3 has a cast iron cylinder head... Could be wrong though.
Senior User
Joined: Apr 2004
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From: Hickory Tavern, SC
This is good for GM but when you check 2004 models silverados had 350 TSB's and F150 had only 59 and this being on a new redesigned truck. Check out at www.nhtsa.gov. So I guess GM's quality is one up on Ford.
Last edited by F250Wildman; May 3, 2005 at 12:21 PM. Reason: spelling
Posting Guru
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From: Jackassville
Originally Posted by 1956MarkII
Yet. If there will be problems, it will take time for them to show up. And if they do, you'll have a group of GM owners that will be a LOT more angry than the 2003 6.0 owners. At least most of those problems were solved with a re-flash; how does one "re-flash" a head? As for the 6.0 problems, it's my understanding that Ford marketing forced the engine to market too soon, over the objections of the programming engineers. They (the engineers) wanted 6 more months to work out the bugs, but the "powers-that-be" over-rode them and said, "build it." They'd risked problems vs 6 months of no diesel production. And they lost.
The Duramax (Izuzu) has been in production for about 5 years now, with no problems regarding alumum heads. I often hear people say what a mistake it is, but it has worked perfecrty so far. I doubt there will be any issues at all, the largest Diesel manufacturer in the world doseant get to that spot without knowing what there doing.
Unlike Ford, Izuzu is not using customers as guniea pigs.
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Posting Guru
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From: Jackassville
I forgot all about the Vega, my parents had one, what a STINKER. Blew headgaskets all the time. The block cracked at one point, so my dad welded, and it worked. That car was sold qucikly as we were afraid it was going to exlpode.
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Originally Posted by polarbear
3. Find the software engineers that did the R&D work for the 6.0 engine controls and send them back to Microsoft. Computer crashes on a PC are annoying- on a vehicle it's a headache at best, downright dangerous at worst. I'm particularily concerned that this group doesn't get hold of the next generation of PSD's.
Posting Guru
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Originally Posted by FERacing66
Unlike Ford, Izuzu is not using customers as guniea pigs.
Originally Posted by DMAX-HD
Being 1 - I can tell you there are more then just programming issues go on there. More then likely it wasn't Microsoft tools used for programming but rather some very basic, low-level assembly language that mitgated motor functions depending on supplied variables and parameters.
Post Fiend
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From: Damascus-Boring, Ore
It's not whether you have problems, but how you handle them that counts.
"General Motors has extended the Duramax 6600 fuel injector warranty coverage for owners of all 2001/02 model-year Chevrolet and GMC Duramax 6600 equipped pickup trucks. Special Policy #04039 was sent to all current registered owners in June of 2004 indicating that additional warranty protection is now available for a period of 7 years from the date the vehicle was placed into service or 200,000 miles - whichever occurs first."
"General Motors has extended the Duramax 6600 fuel injector warranty coverage for owners of all 2001/02 model-year Chevrolet and GMC Duramax 6600 equipped pickup trucks. Special Policy #04039 was sent to all current registered owners in June of 2004 indicating that additional warranty protection is now available for a period of 7 years from the date the vehicle was placed into service or 200,000 miles - whichever occurs first."
Postmaster
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From: Marion, VA
Originally Posted by polarbear
It's not whether you have problems, but how you handle them that counts.
Post Fiend
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From: Damascus-Boring, Ore
As we beat this dead horse once again... 
Ford TSB's 12798 and 12799 deal with piston slap on certain 4.6, 5.4, and 6.8 engines produced before 4/14/99. As with GM, there are many motors with this dreaded problem
that have logged well over 100K miles.
Ford TSB's 12798 and 12799 deal with piston slap on certain 4.6, 5.4, and 6.8 engines produced before 4/14/99. As with GM, there are many motors with this dreaded problem
that have logged well over 100K miles.