Alum. Heads

[brobeson]

While I am a long way from a Chevy fan I thought I would just say the Mercedes Bends has used Alum. heads on there V-8 diesels for many years, they have no problems.

There is nothing wrong with alum. if engineering and design then the manufacturing is correct.

Did anyone read the 4 wheel magazine a few months back that compared the Cummins, PSD and Dmax, they still said the Cummins was best for towing, fuel mileage, reliability.

Bob



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1998. 5, 2500, SLT, 24V, 4X4, Auto, 4. 10 towing 35ft. 5er

 

[lschultz]

I beleive the diesel(TDI) that VW uses has a aluminum head. I just bought a NB. If you have not drove one lately you are in for a surprise.

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2000 Dodge 4x4 Quad Cab SWB 5-SP
AMSOIL dealer/user

 

[CrewCabDiesel]

In case you are interested, My next door neighbor works at a plant where they make Cummins aluminum HEADS & BLOCKS for marine apps. and miltary use.

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1985 DODGE 1 ton Crew Cab(imported from California with no rust) W/8' box converted to 4X4 in 1999. Converted to a non-intercooled 1991 Cummins Turbo diesel & rebuilt 5 speed Getrag in 2001(wife can't drive a stick . Freshly rebuilt and Balanced Cummins, Rebuilt NP205, Rebuilt Injector pump and tweaked, Matched Injectors, 3" New Mandrel Bent Exhaust,no muffler, Borgeson Steering Shaft, K&N Air Filter, 4:10 gears, limited slip rear end, 16" Goodyear GSA Wranglers, 16K Reese 5th Wheel Hitch,and LE Package and a Sony CD Stereo. Next add-on some “Banks” toys ! If you want to know why I did all of this, 2 kids, one on the way and I can't stand F**d and Ch**y. Kyle Hoover ,Fruitport, MI.

 

[Gary - K7GLD]

DUNNO that aluminum heads on a diesel CAR are necessarily a problem, if good materials and engineering are involved - but a TRUCK sees loads and usage NOT common to cars. That's why even the gasser engines still use cast iron blocks, 4-bolt mains and stronger crankshafts on engines intended for trucks. The GM LS1 V8 used in my '98 Camaro SS is all alloy - but the same version of that engine used in GM trucks uses a cast iron block - not sure about the heads... There's been enough problems with the all alloy LS1, that the serious power freaks are switching to the heavier truck blocks after blowing up the alloy job their cars came with...

Only time will tell how the aluminum heads work out on the GM duramax - but *I* would sure hate to be a factory guinea pig and field tester (at a cost of $40,000 or so!) on an unproven product. Over-the-road 18 wheelers are as weight-conscious as they come - as WELL as durability minded, and how many aluminum heads do we see on THEIR bread-and-butter trucks? #ad


Proving out the GM DM engine won't happen on the short-term, unless serious design flaws exist - give them at LEAST a year and over 100,000 or more of intensive use, THEN we'll have a better idea of their "excellence" - shucks, only within the last several months have the various problems and early failures of the Ford PS started surfacing, and THEY have been out for a couple of years now! #ad


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http://community. webshots.com/user/davison71 Early '91 250, 727 AT, 307 rear... Banks Stinger exhaust, intercooler... US Gear OD... Tweaked pump, upgraded radiator... MORE than a match for every new PS Ford encountered so far...

"Dura" WHAT? NOW I know where all those recycled beer cans go...

 

[JohnE]

If aluminum is questionable in engine blocks and/or head then why do most engines use aluminum pistons? Some aluminum alloys have much better wear properties than steel or cast iron for engine applications. The reverse is also true. Joining the two together (cast block & alum heads) are a big problem. Each has different coefficients of expansion that really tests a head gasket. An alum piston and cast block combination has the best slop compensator ever developed, the piston ring.

For me I'm glad that Cummins sacrificed the few pounds of weight saving to stay with a cast head for our engines.

Cheers;
JE

 

[Gary - K7GLD]

"If aluminum is questionable in engine blocks and/or head then why do most engines use aluminum pistons?"

SORRY to appear cranky, but... #ad


He!!, I've heard that tired old bit too many times already! #ad


SO, if LEAD is so bad, why did they use it in rod and main bearings? If Copper and brass are so bad, why do they use it in radiators? If rubber is so bad, why do they use it in tires?

BUT we're not TALKING about pistons, bearings, radiators OR tires here, we ARE talking about HEADS that take an entirely DIFFERENT work load and stresses! *I* for certain, would NOT want lead, copper or rubber heads on MY truck - but they do just FINE for what they ARE currently used for, just as ALUMINUM does in pistons, and SOME engine heads! #ad


A comparison between material used in HEADS, and that used in OTHER parts of an engine, in completely DIFFERENT functions, is WORTHLESS! #ad


But YEAH, *I TOO* am glad for the cast iron used in the head on my Cummins! #ad
#ad


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http://community. webshots.com/user/davison71 Early '91 250, 727 AT, 307 rear... Banks Stinger exhaust, intercooler... US Gear OD... Tweaked pump, upgraded radiator... MORE than a match for every new PS Ford encountered so far...

"Dura" WHAT? NOW I know where all those recycled beer cans go...

[This message has been edited by Gary - KJ6Q (edited 04-07-2001). ]

 

[PRout]

Aluminum pistons are used because they are lighter. They will rev quicker. Aluminum heads are used because they are cheap, and will make more revenue for the mfg when they need to be replaced.

 

[PRout]

What ticks me off is bronze muffler bearings, & aluminum piston return springs!

 

[JohnE]

We're talkin about engines, not ham radios or blenders. Why is aluminum readily accepted on the bottom half of the combustion chamber but questioned on the top half? That means piston versus cylinder head for the lead brains out there.

The original GM diesel was basically a converted gas enginer block. It failed miserably as a diesel, but the gassers consumed every available block due to the durable it gave them for racin applications.

The answer is applicability. If aluminum is best for a piston, use it. If aluminum works best for a gasser head, use it. If aluminum gives you the most bang for the buck, use it. If cast iron or forged steel gives you the longest life put it in a Cummins or Detroit.

Tommorrow may be different.

JE

 

[Champane Flight]

I believe in the future we will see more and more applications of aluminum in light duty diesel applications. They are lighter by a couple hundred pounds. I do not believe that heavy duty engines(Cummins) will go to aluminum heads. What we all have to realise is that most people want a new pickup every two or three years and will trade them off every year or so. Most are looking for that new thingamagig,power,or just that new car smell. At that rate you will never get the mileage over 100000.

I keep my vehicles forever,I am always getting kidded about it,and always reply"It still runs great and I am not making a payment on it". We will see how many of the aluminum heads on the Durastroke will make through the summer. I have to admit for a new model they are holding up pretty well so far.

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95 Dodge 2500 Luverne grill guard,headache rack,running boards and Amzoiled. Soon to be mildly bombed. 84 Dodge d-150, 318 Hooker headers,Edelbrok intake,mallory ignition,Carter Afb,Accel coil,and Custom dual exhaust. Boat,fifthwheel,motorcycles,and shop. 72000 as of 3/1/01,not even broke in yet. Old Dodge 126000 miles and running better than new.

 

[Expat]

I think the newest generation of Land Rover turbodiesels (not available in the US) have aluminum heads and iron blocks. I don't know about earlier generations. By all accounts the TD5s are pretty good engines, but I haven't heard much about durability yet. I seriously doubt they'll last like a Cummins.

 

[BCFAST]

Someone above posted the proper answer to this. . differential thermal expansion. The iron block and alum. head thermally expand at different rates, possibly causing gaps between them or cracking. And, where the VW tdi motor cant be killed with an axe, the aluminum-headed MB and BMW gas motors DID have some terrible heat problems years back. . I think the contemporary cars are much improved, so it may have been a metalurgical issue.

 

[Alan Reagan]

I believe in marine applications, most are used for generators. Steady RPM, long run periods with nothing changing. That application would/is probably OK because you are not getting the start/stop thermal cycles you get in a truck engine. They bring the generators and even the propulsion units online and reach operating temps before any load is applied. Then they run for weeks before they are shut down. In that application, aluminum might work OK. Constant cycling is where I believe they may have a problem, long term. I am an engineer and I've seen what I thought were the best designs fail during the required "shake and bake" where we shake and thermal cycle from
-20C to 100C with the unit operating. The failures are usually dissimilar metals expanding and contracting at different rates along with gasketing materials that won't allow that to happen over long periods. The heads may last. The head gaskets may not. I don't know. GM probably doesn't "know" either. Cummins and Cat know on their products.

 

[Gary - K7GLD]

When most of us visualize the differential expansion problem in aluminum/cast iron, we tend to think primarily only in terms of the HORIZONTAL plane, or front-to-back on the top cylinder surface. That IS important of course, and the relatively large dimensions involved DO present a challenge - but there is ALSO the expansion problem as it affects the THICKNESS of the heads and the length of hold-down bolts!

This has been a problem with the all-alloy GM LS1 V8, where heavier use and more extreme pressures and stresses actually allow the heads to"lift" off the block momentarily under high cylinder pressure, ultimately leading to blown head gaskets. GM uses "torque to yield" alloy head bolts in these engines (can only be used *1* time!) in an effort to match their expansion rates to the head/block, but apparently, the material used is not sufficiently strong compared to usual materials in this service, and they often fail prematurally. AND, conventional hardened iron bolts would be even worse...

MORE food for thought... #ad


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http://community. webshots.com/user/davison71 Early '91 250, 727 AT, 307 rear... Banks Stinger exhaust, intercooler... US Gear OD... Tweaked pump, upgraded radiator... MORE than a match for every new PS Ford encountered so far...

"Dura" WHAT? NOW I know where all those recycled beer cans go...