Bus Smoking Issues...Still?

[PeasAndCarrots]

So after finding what was wrong with the passenger side valvetrain, and pulling the head (was cracked at the #2 or #4 valve), replaced the front two cylinders' lifters and pushrods, bought a new (used) head, and installed it using the Fel-Pro head gaskets. Fired it up today and it sounds great!

One problem...it's still smoking as badly as it was when the head was cracked and the valves were inoperative. White smoke...

-Cracked head indicates the engine might have overheated at some point in the past - is it possible for 6.2 diesel blocks to crack/leak coolant?
-Could the white smoke be from the lowered compression ratio due to the thicker head gaskets?
-What would the symptoms be for air in the fuel lines? Can I rule this out if the engine's running smoothly?
-The new head came with non-interchangeable injectors (coarse vs. rough thread). Could a bad injector cause white smoke? How do you test for a bad injector?

[john8662]

-Cracked head indicates the engine might have overheated at some point in the past - is it possible for 6.2 diesel blocks to crack/leak coolant?

These heads crack from normal service too, so a cracked head (depending on the cracks found) isn't indicative of abuse. On the second question, yes, but you'd likely be getting pressure into the cooling system too, or you'd be mixing oil and coolant.



-Could the white smoke be from the lowered compression ratio due to the thicker head gaskets

Did you install a thicker head gasket? The standard thickness gasket is as close to the factory gasket as possible. The only alternative is a .010" thicker gasket that will drop your compression around 1 point. If the engine was already low compression, yeah, that wouldn't be good. It should still run clean after warm-up, just be hard to start.



-What would the symptoms be for air in the fuel lines? Can I rule this out if the engine's running smoothly?

A clear line on the outlet of the injection pump (return line) and watching it run will help you there. I don't think this is the source of your white smoking, unless it's missing and really running poorly, but it usually won't stay running.




-The new head came with non-interchangeable injectors (coarse vs. rough thread). Could a bad injector cause white smoke? How do you test for a bad injector?

I don't like the sounds of this solution. All G-vans are supposed to use the fine threaded injectors that are short-body, for clearance in the van of course. The 82 engines were the only heads that used the coarse injectors. There wasn't a Van configuration with the 6.2 in it in 82.

Yes! injectors could certainly be your cause. To check this have the engine running and loosen an injector line nut as to cause it to leak, the cylinder will cease to fire (fuel pressure drops too much to pop the injector itself). If the smoke goes away (and engine will miss as a result) then that's the cylinder causing your grief. The while smoke could be retarded injection pump timing too, try advancing the timing a couple line widths. Do this adjustment with the engine NOT running.

J