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6.2 question

Discussion in 'The Garage' started by BIGCHEVY4X, Jul 7, 2005.

  1. BIGCHEVY4X

    BIGCHEVY4X Registered Member

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    Maybe someone has some helpful ideas to whats wrong with my 6.2? I picked up a 6.2 from a guy that had pulled it from a military truck and i droped it in my 82 pickup. the old 6.2 had overheated and blown the heads (previous owner) The motor is running but is sluggish and slow compared to other 6.2's it seems to have alot of white smoke going uphill doing 35. It starts really hard in the morning but seems to run fine after it warms up. The glow plug controller was busted so it i replaced it with a manual in cab switch. I dont know if it something like old glow plugs or retarted injection timing. bad injectors or pump. Could it be a leaking head gasket or maybe just a missing wire or something simple. Does anyone have any ideas?
     
  2. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Did you check to make sure that the block wasn't cracked, or warped or something?

    White smoke in the exhaust typically indicates that the vehicle is burning coolant.
     
  3. BIGCHEVY4X

    BIGCHEVY4X Registered Member

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    yes i cleaned the block up really good and didnt see any cracks or defects it didnt appear to be warped but i didnt really check for that
     
  4. ksmeltzer

    ksmeltzer Registered Member

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    White smoke on a diesel is usually a sign of lost or incomplete fuel delivery.

    Do you have an auto tranny if so are you having trouble with it shifting. If so it is almost assured that it is the vacuum pump. The vacuum pump provides pressure for the crankcase depression valve. If you pump is shot the valve will not function right. And cause the engine to smoke as well it will cause the TH400 to shift hard or not shift at all.

    Do you run a dual exhaust? If so are you getting white smoke out of each side or is it one side if so then it could be a clogged injector.

    It could be a leaky injector pump.

    Finally, it could be caused by timing.

    My advice:

    Do a vacuum test.
    Inspect the fuel line / injector pump for leaks.
    Check the timing.
    Do a compression test.
    Pull the injectors and have a shop test them.
     
    Last edited: Jul 8, 2005
  5. BIGCHEVY4X

    BIGCHEVY4X Registered Member

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    Thank you very much that was very helpful this is my 2nd truck had my first had a 350 so if anything was wrong it was allways very simple. Im still learning about the 6.2 and all of its componets. I just had my tranny rebuilt becuase it was skipping 2nd gear becuase the last owner fried it and ever since i put the new tranny in it shifts really hard.
     
  6. ksmeltzer

    ksmeltzer Registered Member

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    No prob,
    Diesels are very easy they just get a little getting used to they have their own quarks. In the end they are usually easier to diagnose that gas engines when you get used to them.
     
  7. JEBSR

    JEBSR 1/2 ton status

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    hard to start

    One problem I may see is the hard to start part. If you didn't convert it to 12 volt glow plugs then your in cab switch still won't work due to the fact that the military engine has 24 volt glow plugs in it. Therfore still not to working for you.
     
  8. diesel4me

    diesel4me 1 ton status Premium Member

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    Th400??

    If you have a TH400 tranny,it might be shifting hard due to the vacuum modulator not getting the proper amount of vacuum from the vacuum pump...my 6.2 has a TH400,and the switch that is hooked in with the throttle cable that controls how much vacuum goes to the modulator was not working right,( diesels have a vacuum pump,which has a constant vacuum--the switch makes this constant source "variable",so it acts just like the vacuum a gas motor would make at different throttle openings)--and my tranny would stay in first gear until 35mph,and slam into second,and it usually refused to shift into third until 50+ mph!...that made city driving very frustrating,and more than once I nearly got pulled over for speeding,trying to get it to go into third!... :doah:

    I could not find another vacuum switch,either new or used--so I asked a local tranny rebuilder what I could do--he said I could spend 120 bucks for a cable operated modulator,like cars with a blower have to use--or do what he does--run the vacuum hose from the modulator directly to the vacuum pump,and screw the adjustment screw in the modulator(located INSIDE the nipple the hose plugs onto!) all the way in until it seats gently(DO NOT TIGHTEN IT)--now my truck shifts like a caddy,nice and smooth--and almost TOO early...its in third now at 15-20 MPH!...sometimes I pull it down into second manually so it wont lug ecessively....so far,after a long hard winter of beating it plowing,it seems to be hanging in there...hope it stays that way!...

    I'm hoping having "constant" vacuum wont cause my tranny to slip or run hot..havent seen any ill effects yet--the tranny rebuilder said not to worry about it,he's done it to dozens of TH400's in diesel trucks and no harm is done... :crazy:
     
  9. clancy84

    clancy84 Registered Member

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    I read your post, and at first was wondering what you were talking about with white smoke being fuel related, I thought it was always moisture related. but I did some searching and found what you were talking about....good info.

     
  10. BIGCHEVY4X

    BIGCHEVY4X Registered Member

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    also a note.... my truck has very poor gas mileage, but it sounds like the first step is a vacuum test. How would i go about doing that?
     
  11. ksmeltzer

    ksmeltzer Registered Member

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    The only 24 volt component on the CUCVs is the starter the rest including the glow plugs are 12 volt.
     
  12. ksmeltzer

    ksmeltzer Registered Member

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    Get a vacuum gauge and connect it directly to the vacuum pump and check the numbers. I don’t know what they are off the top of my head but I will check my book when I get a chance and post them.
     
  13. BIGCHEVY4X

    BIGCHEVY4X Registered Member

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    What are the numbers for the compression test supposed to be? and will a gas guage work or does it have to be a diesel? also What is the readout of the fuel pressure guage range? My guage is about middle at idle and once you get going it shoots up to high. Is this right? Usally guages stay about middle. Is this why my oil cooler line blew a dime sized hole on the freeway yesterday?
     
  14. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Minimum compression is supposed to be 300 psi.

    Rene
     
  15. JEBSR

    JEBSR 1/2 ton status

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    oops

    Oh yea thinking of hummers. Sorry. :doah:
     

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