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  #16  
Old 09-24-2001, 02:21 AM
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Location: Battle Ground, WA
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Mssg to PSFred...

Hi there,
I don't have any particular allegiance to GM, but I think your commentary and opinions of the chevy small block neglect the facts. The 300D has a main bearing diameter of 2.798". The Chevy 4.3 has a main bearing diameter of 2.45", or roughly .35" smaller, but the shaft is only half as long, and the combustion forces are striking the shaft from two directions 90 degrees apart, so it has much less need of large main bearings. The 300D rod bearings are a very small 2.078" in diameter! The Chevy rod bearings are 2.5" in diameter, almost a full 1/2" larger!! You refer to the skimpy skirt of the chevy piston - have you ever seen one that showed any wear, if the engine was taken care of? I haven't seen any with significant wear! The rings on both engines seem to last about the same. The Chevy has a roller cam, the 300D does not. The Chevy has stronger cam drive gears and chain. I know the 300D is a terrific engine, but it is not without its problems, and I truly believe that the chevy engine, at 1/4 the price out of the box, is a better value. The Mercedes body, on the other hand, is a piece of quality craftsmanship that isn't equalled by anything produced in the USA... Solid, rattlefree, and comfortable. Please understand by my comments that I'm not trying to argue with you, just wish to make some positive comments towards the 4.3L engine. By the way, the 4.3L engine can produce 200hp (net) in the vortec version and 260 ft/lbs of torque, while the 300D turbo engine produces only 120hp (net) and 170 ft/lbs of torque. I know that all you diesel fans out there are going to say that diesel power is "different", but it really isn't. The torque is what moves the car, and 260 ft/lbs of torque moves a car a lot better than 170 ft/lbs, as I can personally verify.
The Chevy small-block was first designed in 1953, but has undergone continuous refinement ever since, resulting in a truly fine piece of engineering currently. The Mercedes 300D didn't make an appearance until 1981, but the basic engine designs are older than the chevy. The fact that it has been around as long as it has is a tribute to it's durability, and the same goes for the chevy. I am well aware that GM has loosed some designs upon the motoring world that were not quite ready for home use - for instance the infamous Vega aluminum engine, the Cadillac 4.5L that was famous for spinning bearings, and most all their diesel attempts. But the 4.3 is an excellent product.
Hope I haven't offended anyone with my ramblings!
Richard Wooldridge
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  #17  
Old 09-24-2001, 09:53 PM
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Join Date: Aug 2001
Location: Evansville, Indiana
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Richard:

The Vortec is a new design, not the old 350.

All of the newer engines are a vast improvement on the old, mainly because GM discovered the idea that all the parts should be the same size, not just fit the the holes with lots of slop!

If you look at a 350 crank next to an MB crank, you will know immediately why the MB lasts longer. It weighs twice as much, for starters.

The 300D was first sold in 1975 (my brother has one, SN <29,000). It was the four cylinder block with a fifth cylinder added -- literally. Original design dates from pre-Hitler, had overhead cam in the late 1930's. MB also made countershaft crown gear drive valve trains, clutched blowers (half way down the synchro clutch engaged the Roots blower), etc.

GM just shoves any old crap out the door, in general.

Torque is the key to acceleration -- what makes our old diesels driveable is that the torque curve matchs actual driving pretty well -- usually peaks at 2400 rpm or so. Lots of fun to get the old Volvo wound up and let her rip -- the slow start confuses gasmobile drivers, and I run away from them as the old girl shifts up and takes off.

And diesels with auto trans a lousy in snow -- way, way too much torque. My Volvo is even a pain on wet pavement -- very easy to spin the tires (both of them, without positrack!). Horrible on ice or snow -- the turbo comes up and the wheels spin like crazy. I expect the 300D to be worse -- more torque.

I suspect a manual tranny would be much better -- more control over what the engine is doing.

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #18  
Old 09-24-2001, 10:10 PM
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Location: Carol Stream, Il, USA
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I agree with Richards's comments about the Chevy 4.3L engine. I have owned my Chevy Astro since new (150HP non vortec version) and the only engine related problems was that I replaced the o-rings for the injectors. I belive that the fuel injector cleaner I used ate away at the original o-rings. The only other minor problem is that my rear transmission seal is starting to leak.

My only complant with this engine is that the valve seals tend to leak which causes a puff of smoke when starting the engine. Since access to the valve seals is very difficult on a Astro van I just live with it.

I do firmly belive that the quality of an engine is directly related on how well it has been maintained.
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1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles
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  #19  
Old 09-24-2001, 11:05 PM
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Location: Evansville, Indiana
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Ray:

We've had several Astro vans at work -- they all threw a rod before 200,000 miles.

O-rings die of old age -- it wasn't anything you put in the gasoline. They need to be replaced every six years or so, along with any and all vacuum lines.

My old (92) current work van has 282,000 miles on it, but we change oil every 3000 miles or less, and use good oil. These are usually driven several hundred miles a day, seven days a week, too. This is fairly unusual for a GM -- they usually crap out about 150,000.

If you are burning oil, I would definitely recommend valve seal replacements however much of a pain it is. The oil ash eats rings and cylinder walls. The drawback is that you will find that the valve guides are worn out and the valve springs shot, and will need to do an overhaul. When the heads are off, you will also find the cylinder walls shot, the pistons bad, etc, etc. Bearings are already marginal, as they aren't up to snuff from the factory.

Listen carefully -- if you start to hear "diesel" sounds from the engine at low speeds, you have a rod bearing knocking and the rod will be out the side of the block shortly!

If you have oil in the air cleaner from the crankcase ventilation, get rid of the motor -- they go fast once the blowby is too much for the PCV system.

I'm still not impressed with the new GM engines -- a decent MB will still have good valve seals at that age and milage, or a Volvo -- had to put a head on my sisters 740 turbo this summer because she blew the upper radiator hose nipple off the radiator on the interstate -- fried the head. Bottom half nearly new, the only other problem was a leak at the distributor seals with 160,000 miles on it.

Oh well, maybe I'm wrong, but I will stick with MB for the forseeable future!

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #20  
Old 09-25-2001, 08:38 PM
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Join Date: Dec 2000
Location: Battle Ground, WA
Posts: 576
More comments....

Hi again,
I should have specified "300D TURBO" in my previous post - I was referring to the turbocharged diesel as being introduced in 1981, as that's the engine I used for horsepower and torque comparisons. Sorry to have missed doing that!
PSFred, the Vortec engine is derived from the 350 - the rods are the same part number, as are the main and rod bearings. I agree that it is a considerably re-engineered engine as regards oil sealing, intake manifold sophistication, computer controls, etc. But the basic block and head designs still retain their 350 heritage.
After reading the various comments regarding poor performance in the snow, I went out and looked at my old 300D engine, and sure enough, the engine is actually sitting slightly ahead of the front axle in the 123 chassis. This makes for a poor front/rear weight distribution in the car, which I'm sure accounts for most of the problems in the snow. I didn't experience any problems with my setup, but the engine is mostly behind the axle, and probably has close to 50-50 weight distribution, plus it's lighter on the front than the diesel powered car. I don't buy the "too much torque" idea that psfred has, because my car has MUCH more torque, and also has lower gearing in first gear, and is quite controllable. I do know that our '74 280C had the same problems in snow that others mentioned, and it also has the same weight distribution problem - the long 6 cyl inline gas engine hangs out too far in the front.
Once again, I'm hoping for constructive discussion, not just slamming for the sake of slamming...

Regards,
Richard Wooldridge
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  #21  
Old 09-25-2001, 08:43 PM
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Location: Carol Stream, Il, USA
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Peter,

Thanks for sharing you experience with high milage Astro vans. I will keep my eyes and ears alert for early signs of failure. Since my Astro van is not driven much, it might be a awhile before I hit the 200,000 mark.

I did experience the bent rod (it didn't go through the cast iron block) and blowby with my 79 Toronado (350 Olds engine) at about 150,000. Since I was not the original owner of the Toronado there was a good amount of sludge build up under the valve covers.

I had the valve covers partially of on my Astro about 6 months ago and as with my Honda (owned since new) it was so clean that you could eat off of it.

Both my Astro and Honda has had 2,000 mi oil changes for the first 100,000 mi, then I extended the oil changes to 3,000 mi. Since my Astro has not been driven much lately I switched to Mobil 1 oil.

I am not implying that my Astro will be trouble free forever, but I am attempting to give it a healthy start.
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Ray
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles
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