Makes me glad we have an S-3, no turbo to cause grief.

Turbos do not cause grief. Carelessness prepping any locomotive for cold weather causes grief. My T6 has both a guru and a Hotstart

If you find that the cost to repair all of your freeze damage is getting high, I have a low time 539 with the improved Alco turbo that I will let go for $7,500.

PM if interested.

Diesels can't run 'rich' at least in the way gasoline engines run. Any increase in fuel will cause an increase in power/speed of the engine, until there is more fuel available then air. At lower throttle settings, I doubt the turbo plays a major role. Some engines incorporate a boost pressure sensor, that limits the fuel until the turbo spools up, tho I doubt this one has that. In short, I think if you are slow with the throttle and let the engine wind up before you give it another notch, you should be OK. You likely won't be able to use the top few notches without black smoke. How well the loco works in the real world like that, is anyone's guess. I think I'd try metal stitching that crack before I tried running it without a turbo. Seems like a lot of work to engineer the turbo back out of the engine.

I would surely think that in any solid-injection engine the governor and the fuel rack (or equivalent) are mechanically related. A turbo increases the effective charge density, allowing more fuel per unit injection; if that charge air density is missing, you will INEVITABLY be rolling coal at almost any speed. (The analogy to 'Alco smoke' is an apt one; if the smoke is due to turbo lag, and the turbo effectively 'lags' forever, what would you expect the smoke to do?)

EDITED to avoid throwing anyone off with 'bad advice' -- you may be able to modify a turbo engine to run NA, but it's involved. I had thought there were no actual differences in injector or line size, but I am not a 539 expert and it turns out there are.

It was interesting to be right but get literally 100% of the details wrong. That surely doesn't happen very often!

There have been a few cases of people trying to run the turboed Alco 539 engine without a turbo. It created very large amounts of black smoke and I know of atleast one engine that was destroyed as the result of it.

There is not case of resetting any rack on the 539 engine to change from a turbo to a non-turboed engine.

The following parts are all different: Air intake system, camshaft, injectors, fuel injection lines and pistons.

Out of curiosity: What are the chamber volume or compression-ratio differences between turbo and non-turbo engines? Is there a different shape to the top of the pistons?

To put it in perspective, I do standby generator service as a job. I recently did a commissioning on a 48kw (yes it's a LOT smaller then a loco, more like a car or small pickup engine). When putting a load on it, it ran fine to about 30kw, with more load it started to loose speed and the black smoke started rolling. Turns out there was some debris stuck in the exhaust side of the turbo, locking it up. In other words, lacking a turbo, it was able to make well over half it's rated power without any noticeable effects at all. I would expect similar results from most 4 cycle diesels.

Cast iron cannot be welded, by any means we here possess. However, for a specialist with specialty equipment, it is possible. And guess who one of the leaders in the field is: Lock-N-Stitch. Most of the work Lock-n-Stitch does for WRM is welded, not stitched. They have a good web page on how they weld cast iron and why you can't.

(lots of welding-supply vendors will tell you otherwise, nickel rods and all that, but they're talking about ornamental cast iron where strength is not required. Ask them if it's OK on a connecting rod. )

You really need to fully disassemble the turbo, mask off machined surfaces, media blast all unmachined surfaces (inside and out) to bare metal and magnaflux. You need to find every crack so you can assess how best to approach things. Then you'll need to recheck internal geometry for warpage and remachine if necessary. Might not be too bad on a turbo, as there are only a couple of critical-alignment points.



The issue is the balance between the governor and the exciter. As you know, diesels always take a full gulp of air (no throttle plates) and engine power is controlled by changing the amount of fuel injected per stroke, this being called "rack". Below stochiometric, the engine is running "lean" by design. Above, fuel is left unburnt and you get smoke or flame.

The fuel rack is calibrated so at maximum "rack", it injects the max fuel that the full gulp of air could burn, assuming the turbo is working. So if you bypass the turbocharger, "maximum rack" is set too high. That only matters in notches 6-8 right? Wrong. Here's why.

The locomotive's notches or throttle command the governor to a specific RPM, like a ship's telegraph ringing down to the engine room. The governor is like a little ship's engineer, his eye comparing the telegraph to the RPM gauge, and his hand on the fuel rack. If commanded 500 RPM, he will use ANY fuel rack position including full rack to get up to that speed quickly, and stay there.

The other part is the exciter. The more current through the generator field, the more load (drag) on the engine, and the more power generated if things are working. The exciter matches its load to what the engine is expected to be able to generate, which assumes the turbo is working. If the exciter overloads the engine, it would "bog" and slow down RPM.

So you see what happens if you remove the turbo. If the engine is capable of 200hp (turbocharged) in notch 3, the governor will rev the engine to the correct RPM. Then, the exciter will load the generator to make 200hp, (which the engine is incapable of doing at that RPM without its turbo) - since load exceeds power, the engine will "bog" and slow down - the governor won't like that, and will command full rack - making lots of smoke. This is an unworkable situation because the governor and exciter are fighting each other.

Both rack and exciter would have to be recalibrated for the engine's lack of turbo.

I've seen the reverse happen on a GE 44, where broken auxiliary generators and a soft battery resulted in insufficient voltage for the exciter, leaving the generator underexcited and drawing too little power for the engine's RPM - the engines were thrashing nearly unloaded, at 75% with 100 amps on the meter, pulling a trivial 3-car train it could handle at 25% if the exciters were getting good voltage. It's difficult to say whether thrashing or lugging is worse for a diesel.

An update on the turbo issue:
I talked with Gary Reed from Lock N Stitch and I am going to attempt to use their C series stitching pins to repair the turbo crack. As soon as he gets back to me with a price on their stitching kit I'll place the order and get started on the repairs. I have no expectations other than to "give it a try" and see what happens, but if I can avoid replacing the turbo at this point it would be a good thing.

Is it just unpressurized water back there? You might consider JB weld or Dev-Con or whatever your favorite 2 part miracle epoxy is. I know, I know, some people will groan but I've had great luck over the years using epoxy. My dad fixed a cracked radiator tank with epoxy and a phenolic patch panel, and it went for years! Worst case you can hit it with a torch and wire wheel and be back where you started.