94 Chevy 3500 series

Looking at a diesel for sale. I know there was some problems with the old Chevy diesel's, but are they any good?

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Anybody have 2cents to add?

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a newspaper company part time from that era with the diesels, loaded twice a week so heavy the rear bumper scrapped going across intersections. I dont remember any major break downs, head problems, block failures during that time span, We drove them hard, two speeds,throttle wide open, or brakes on hard (single copy, newspaper racks, magizine stands etc)The injectors and injector pumps held up well, the tranny stayed together(TH400's I believe).They were driven two shifts a day, some three shifts. Biggest issue I remember was glow plug issues. If the power steering fluid was kept clean, and power steering fluid not auto trans fluid used, we didnt have issues with the hydroboost brake system ether. These were 18 foot step vans.
Whitelightning
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Thanks for the update. I found a 94 for $3800 that they say ran good when it was traded in two months ago. But now something is up with the motor. They said probably somebody started it too quick before the glow plugs were warmed up and messed up the injectors. We will see.

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The purpose of the glow plugs is to warm the combustion chamber enough to ease starting. I am sure you are aware that a diesel is a compression ignition engine, ie the compression of the air in the cylinder is such that it raises the cylinder temperature enough to cause the fuel to ignite when it is injected. Heavy duty trucks do not have glow plugs because they have even higher compression ratios than the light duty diesels and as such do not need them. So I fail to see how a defective glow plug could cause an injector problem. The biggest causes of injector and injector pump problems are dirty fuel, and water in the fuel. This is why it is so imperative fuel filters get replaced on a very regular basis, and the water separator drained, and don't buy fuel from Joe Blows' Discount Emporium fuel stop. I would walk from this one unless they repair the issue BEFORE you drive it off the lot. Besides injector problems because the compression ratios are so high, there is very little clearance when the piston is TDC if there is a leaky injector, it could have internal damage from partial hydrostatic lock.
Whitelightning
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Again, thanks for the info. That may explain why they said it may need a motor replaced. He fired his mechanic, and he is not sure what is wrong.
I guess I was wondering if these motors were a remanufactured 305 that GM made into diesels. Sounds like they are a different breed. But you have good advice to walk away from it.
Thanks again..

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<snip>

<snip>
Pardon me for asking, just how high a compression ratio do the "heavy duty trucks" have anyway? My 6.5L has a stock compression ratio of 21.1 to 1 which is even higher than the Power Stroke or Dodge Cummins.
I was not aware of any diesels that have a higher ratio, and in fact, to make our 6.5L diesels run better, we install lower compression ratio pistons, like the one I am building right now at 18 to 1.
I think the reason the heavy duty trucks start easier is the higher pop pressure on the injectors along with direct injection, but I may be mistaken there.
George
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26:1 compression ratios. Lowering compression ratios , what they call low compression CI engines are being looked at hard today. The theroy is lower compression results in longer burn times, as much as 14 crank degrees longer reducing particle emmisions, but it also lowers horesepower and torque output as well. Those rigs I worked on in the service were designed to pull 47-60 ton track vehicles such as the M-60 tank, the M88 Medium track recovery vehicle, and the M-1 Abrams tank and that was before trailer and tractor weight was factored in. They were a vast improvement over the old 10 ton they replaced as far as pull power was concerned, but then they were replacing 30 year old technology. The Cummins NT-14+ 435s I drove last were 22:1 compression, the 500+ horsepower models were 24:1
Whitelightning
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Whitelightning wrote:

George
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