426 D3500 engine problems

Hello:
I have a Allis 426 D3500 series power unit mounted to a Vertical TMR feed mixer about 2 weeks ago When it starts working hard it looks like a super stock tractor in how much black smoke come out and dies. It also starts hard even plugged in, it fires right up on two cylinders and takes 10-20 seconds before all fire. Once running it runs smooth with no smoke or no miss and could start mixer at idle even when loaded. We removed air cleaner and muffler, turbo had NO boost REPLACED WITH NEW TURBO still has no boost, we had pump and injectors check by trusted diesel shop all withing specs. Timing was correct. removed exhaust manifold no blockage, valve train all have clearance, open good and none stuck. The only thing we are down to is compression is a consistent 260 psi on 5 cylinders and 235 on remaining one. I can not find what it should be.Even if low How would that affect the turbo boost once running? A gas engine with a turbo has much less compression than that. I have a 7040 with same engine and a UNI with same both start and run great. Looking for any ideas   

You haven't said what the blow-by hose looks like for fumes. Did this come on it all of a sudden????  You have't given an indication as to what age/year the engine is or what style/brand injection pump it has. Even with the intake manifold gasket blown (which it could be) you still should have SOME boost, unless you're using a gauge larger than 30 psi.

If it is intercooled then the cooler could be stopped up. Its getting fuel obviously by the black smoke but i would still look to where your taking boost pressure from and the turbo you put on is identical to the old one?

Thanks for the input but we removed air cleaner and piping completely so turbo is to open air, there is normal blow by nothing excessive and average oil pressure, I can see turbo running so it is not locked up both old and new turbo spin free with no obvious physical problems, engine runs smooth and to full RPM at no load or even half load with no smoke, we took the boost or lack of, readings at the 1/8" plug for starting fluid. it has about 6"-10" VACUUM from idle to wide open and I'm watching the turbo spinning? on My 7040 it is about 1" pressure at idle and 6-7 at full throttle. Still looking for compression PSI ?   

jbdairy wrote: Thanks for the input but we removed air cleaner and piping completely so turbo is to open air, there is normal blow by nothing excessive and average oil pressure, I can see turbo running so it is not locked up both old and new turbo spin free with no obvious physical problems, engine runs smooth and to full RPM at no load or even half load with no smoke, we took the boost or lack of, readings at the 1/8" plug for starting fluid. it has about 6"-10" VACUUM from idle to wide open and I'm watching the turbo spinning? on My 7040 it is about 1" pressure at idle and 6-7 at full throttle. Still looking for compression PSI ?

May not help you, but I had the spring inside an air inlet hose from the air cleaner to the manifold on a naturally aspirated Perkins.  When the load got too great the hose would collapse and you had to almost stop to get the engine to come back to fuel rpm and boy, was there smoke behind you!  Took me a pump and injector overhaul and a set of new air filters and fuel filter and I can't remember all until I happened to be sitting in the pickup when it went by and started smoking that I was at just the right angle to see the air hose completely collapsed to figure out the problem...

How about a plugged vent from fuel source?

As Mack said a diesel should not have a vacuum at any time unless the intake system is restricted. Start by checking from the turbo compressor outlet to the manifold.

Id go along with Ed,  Ive had the big plug come out of intake manifold and dump all the turbo boost.     It sounds to me like you are loosing your boost somewhere.  Aint no easy answer on this one, let us know what you find.   HTH

If it has a roosa pump, what you describe sounds like a fuel restriction, I know you said it smoked, but with the roosa pump if you have a restriction it will reduce your transfer pump pressure enough to affect the timing advance and it will smoke and have no power, because of late timing,[no timing advance movement] Make sure you have good solid flow to the filters, an air leak will cause the same symtoms. A low pressure electric pump will also help, 5-7 psi max.

It takes one major item to make boost.  I a hot expanding exhaust gas steam, yes you need other things like a turbo, and sealed piping, but those have apparently been eliminated.  Low compression will indirectly affect boost, but if the engine can run, you can build boost.  Every one of these ideas is great, and all are valid, but I am really starting to think PUMP as Kevin stated, assuming all intake pathways are free and clear, and the filter has been changed, which it sounds like JB has pulled his hair out doing.  The only thing left is pump or timing.  Without good advance, and good fuel delivery you will get little to no heat in the exhaust, and therefor no energy to drive the turbo and create boost.  I do agree that it seems odd that a vacuum is present, but when we start our 7060s they have a lot of hours on them, at idle they too draw a vacuum, my guess is because of the hours on them, and it's the same engine.  I think the only thing left is to suggest that the pump just isn't putting out the fuel that it should, and since it seems to be related to RMPs and load, I am afraid it's that time.  Since it starts on two cylinders, and blubbers along for 20-30 seconds and the hard start.  But before you have it inspected again, or rebuilt, I completely agree with Kevin, check all of your fuel flow, i.e. you would think black smoke means too much fuel and no air, but I have seen on other engines a dirty or near completely plugged fuel filter will do the exact same thing, and both those engines both allis 2900s had roosa pumps on them, so really worth a second look into the fuel system.

Sounds like you and I are blessed with the same fortune.

jbdairy wrote: Thanks for everyone's input we had every intake,exhaust, fuel part off AGAIN and inspected more than once, engine actually looked very clean. We got the pump and injectors back from the shop they tested all within specs, reassembled and works fine!!!!!!!!!!!!!! no clue why? we didn't change a thing but when it was acting strange we definitely had No boost and a vacuum on the intake at any RPM even as I'm watching the turbo spinning and yes there was NO blockage at any time in any intake or exhaust piping. I'll say it was Gremlins no other explanation. So if anyone is in need of my old used RaJay Turbo but no guarantee on it. I think I bought the last NOS one from a dealer in Min.

this came on all of a sudden? or after some other work was performed?