White/gray exhaust smoke

Discussion in 'Diesel Tech and 24 volts Systems' started by simtoo, Apr 21, 2010.

  1. simtoo


    Just popped a 1HZ with a 5 speed into a 91 FJ80. All is well except for excessive white/gray exhaust smoke at start up and into the first 30 miles of driving. Engine sat for 2 years, however I have run it for 3-4 hours and it still smokes. I adjusted valves, rebuilt injectors, new filter, new air cleaner and still smoke. My question is, could it be the old gas FJ80 in-tank fuel pump causing too much restriction? I pulled the fuse on the pump because I felt the fuel pressure would be too high for the diesel, however I did not remove it from the tank or fuel delivery system. Any thoughts out there?


  2. I would remove the old gas pump all together
    Does it run smoothly as soon as it starts?
    A number of things cause white and grey smoke

    Air in the fuel
    Injectors opening too early(I think this may apply here)
    Bad compression on one or more cyls.

    Whitish smoke can also be condensation from coolant leaking into the combustion chamber.
  3. simtoo




    Thanks for the ideas. I tested cold compression when I first got the engine and #1 was 425# while the rest were 610#. I am hoping it was just a stuck ring. I have not tested it after a good long run. The coolant does not seem to be a factor. I did read the old gas pump is a vane type that may be offering too much resistance to fuel flow. It starts right up with Wilson switch, but smokes.

    I may bypass the tank to see if that solves the problem. Thanks again.

  4. I think compression should be tested warm and 425 psi would still fire ok when warmed up
    If the gas pump is the problem ,it would be lacking a lot of power.
    Bypass is a good idea;)
  5. simtoo,

    Why not give it a number of heat/cool cycles and some extended operation at temp before addressing the smoke?

    Not to say there's no problem, but I have run across a few used motors that seemed to "limber up" after getting them on the road for a few weeks. The important thing is to make sure they get hot, even to the point of placing some cardboard in front of the radiator to make sure the motor gets well into it's operating range.

  6. simtoo


    compression update

    Ran the diesel hard up the highway today for a few hours. Dumped in a can of Seafoam before the trip. Good acceleration even uphill in 5th gear. Exhaust was clear at the half way point. Temp barely got past the cold mark. I may have to block the radiator to get the temperature up on this diesel because I am in a cold climate 7 degrees C/ 41 degrees F.

    Hot compression numbers are: 1-420#, 2-575#, 3-550#, 4-545#, 5-560#, 6-545#. I quirted engine oil into Number 1 glow plug hole and compression came up from 420# to 480#. I did notice that #1 glow plug had wet fuel still on it, whereas the others were all dry with a little black carbon.

    I tried a portable fuel tank with no change in white smoke amount. After all the tests, it still has white/light gray smoke, but runs smoothly.

    I have one more idea. When I rebuilt the injectors, I twisted off the #1 cylinder leak off banjo (bad corrosion). Having no access to a new leak off manifold, I silver sodered the leak off pipe manifold back onto the #1 banjo fitting. What if my silver soder job constricted or blocked the #1 diesel leak off pipe? Could it force the excess leak off fuel back into the combustion chamber and from there out the exhaust pipe as white smoke?
  7. blis


    in cold north
    the 1# cylinder is bit on the low side on compression, so that might be your problem in this case... However, it might be enough to just drive it warm and then give it some real heavy load, for example slap a heavy trailer and tow it up a hill or just go for biggest gear and push it all the way up to 4 000rpm ... if that doesnt solve the compression problem then most likely you'll have to pop open the engine and see what it has eaten...
  8. simtoo


    I am slowly narrowing down the white/gray smoke problem. I cracked the injector unions one at a time to check for consistent RPM drop and discovered the lower compression (450 psi) #1 cylinder had no effect on RPMs, so it is not firing when the engine is cold. I further discovered that when I disabled the #1 injector by cracking the union, the smoke problem disappeared immediately.

    After the engine warms up for 15 minutes or so, the #1 cylinder starts firing and again no smoke problem. I tried the injector union crack test on the warm engine and all cylinders behaved the same. So I am now focused on the #1 cylinder and trying Marvel Mystery Oil/ Seafoam/ hot and cold engine conditions in hopes of freeing a stuck ring or stuck valve?? Trying everything before I pop off the head and pan to check for a broken piston ring (Worse case scenerio).
  9. Having fuel flowing into the injection pump at more than just a few PSI can affect pump timing....

    Check your valves carefully after the engine has sat all night and cooled fully. The engine must be cool for about 10 to 12 hours before checking the valves.

  10. mudgudgeon


    Sydney, Australia
    incorrect injection timing can be a cause of white/gray smoke too. (see the sticky at the top of the diesel tech/24volt index page)

    It may be worth a look?
  11. crushers

    crushers post ho SILVER Star

    Tara Ontario
    no cardboard needed.
    operating temps will not be affected once up and running.
    NEVER trust the factory temp gauge.

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