I was wondering what the back pressure should be on 7.3l IDI non-turbo?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Joseph Davis, Feb 13, 2018.

  1. Joseph Davis

    Joseph Davis Full Access Member

    Posts:
    108
    Likes Received:
    8
    Joined:
    Nov 23, 2017
    Location:
    Lompoc, CA
    I have a smoker, but I think it is valve seals because I found some of the remains in oil after I changed it. When I take off the oil filer cap it does not blow any smoke out, and it does not have any blow by that comes out in a steady stream at 2000 RPM. But I know I should check the pressure before I pull the heads while she is still running.
    What pressure reading in psi should I get when I put my pressure tester on her?

    I just want to make sure it is not the rings because I am planning on pulling the heads this week end, because I got my Ford Head Gasket set Saturday! Strait form Ford old stock with manifold Gasket included. It Will take about two week to get her done but I think My Beast is worth it.

    Thanks for the help on my glow plug post OIL Burners.
     
  2. Macrobb

    Macrobb Full Access Member

    Posts:
    1,261
    Likes Received:
    409
    Joined:
    Jun 12, 2016
    Location:
    North Idaho
    Advance the timing first.
    Blue/gray smoke in an IDI is partially burned fuel, not oil - with the high compression of an IDI, it'll burn oil cleanly.

    Also, no, you won't get any blowby coming out of the oil filler, because the CDR is pulling it into the intake to be burned(as designed). Any IDI will have massive amounts of blowby, including a newly-built one; that's just a design 'feature'. As long as you have a CDR so it can get burned, you are fine.

    I also want to point out that I haven't bought a single IDI that didn't need timing adjusted. It's just the nature of the beast, what with wear causing retarded timing and everyone being scared to just advance it.
     
    Sidewinded_idi likes this.
  3. Joseph Davis

    Joseph Davis Full Access Member

    Posts:
    108
    Likes Received:
    8
    Joined:
    Nov 23, 2017
    Location:
    Lompoc, CA
    Yea kind of blue / gray and I have been afraid to advance timing because I don't have a timing meter yet. I started running Marvel Mystery Oil in fuel and I got compression back up to 320 psi; in a cylinder that had 120 psi in it warm. I know it is easy to advance timing just mark it on pump line and put it back if nothing changes. I'm just scared because I'm new to being a diesel owner but this forum has given so much good advice. I will bump it 1/8" and post how it does after work tomorrow. I am on my lunch break right now 11:58pm and no a soul to be found! It is going to suck when I get back to working days again. Thank for the great advice.
     
  4. chillman88

    chillman88 Supporting Member Supporting Member

    Posts:
    784
    Likes Received:
    264
    Joined:
    Feb 22, 2017
    Location:
    Central NY
    When I did mine, I'd bump the timing just a hair and drive it a couple days. I finally found a spot where I would noticably LOSE power when the cold advance turned OFF. I bumped it about a dimes thickness from there and haven't touched it since. A little black smoke every now and then but otherwise mostly clean.

    Your results may vary. I'm pretty sure my injectors are way overdue for a change so you might not find the same method working for you.

    You're not going to blow it up advancing the timing if you pay attention to how it's acting. If it gets way too clattery back it off a hair. From what I've noticed and read, the sweet spot has a decent clatter on cold idle and it mellows out a tad when cold advance kicks off.
     
  5. Macrobb

    Macrobb Full Access Member

    Posts:
    1,261
    Likes Received:
    409
    Joined:
    Jun 12, 2016
    Location:
    North Idaho
    If you managed to get it too advanced, it'll be a real bear to start and clatter like mad... but that requires more advance than you can physically rotate the pump(skipping 1-2 ip gear teeth). I've done it.
     
  6. Thewespaul

    Thewespaul Supporting Member Supporting Member

    Posts:
    2,622
    Likes Received:
    958
    Joined:
    Jul 27, 2015
    Location:
    bulverde texas
    I’ve had trucks come to the shop with over 20* that have been running that way for years. You won’t hurt anything
     
    chillman88 likes this.
  7. Joseph Davis

    Joseph Davis Full Access Member

    Posts:
    108
    Likes Received:
    8
    Joined:
    Nov 23, 2017
    Location:
    Lompoc, CA
    Ok, Sold; Heading out to Garage to advance timing. I will let you know how it works!
     
  8. Joseph Davis

    Joseph Davis Full Access Member

    Posts:
    108
    Likes Received:
    8
    Joined:
    Nov 23, 2017
    Location:
    Lompoc, CA
    Still runs ok but I will let you know if the smoke is gone tomorrow because I can not see it in mirror when it is Dark. LOL Thanks for the input. I will try smoking the tires to night.
     
  9. Macrobb

    Macrobb Full Access Member

    Posts:
    1,261
    Likes Received:
    409
    Joined:
    Jun 12, 2016
    Location:
    North Idaho
    How far did you advance it? You may need to advance it quite a bit(you'll have to loosen the injector lines at the pump to keep it from binding), if you still don't have much clatter and still have blue/gray smoke(black smoke is a separate issue, and OK - timing would be 'nominal' to advanced at that point.
     
  10. ISPKI

    ISPKI Lumber Chucker

    Age:
    31
    Posts:
    320
    Likes Received:
    19
    Joined:
    Jul 13, 2015
    Location:
    Granby CT
    I don't mean to hijack but my truck smokes quite a bit when I start it in the morning and there's a little smoke when I open my oil fill cap shortly after shutting it off. To me, the engine chatters alot but it's also my only diesel so I'm not sure what's normal
     
  11. Joseph Davis

    Joseph Davis Full Access Member

    Posts:
    108
    Likes Received:
    8
    Joined:
    Nov 23, 2017
    Location:
    Lompoc, CA
    Hi Guys Advance her quarters thickness but loses power so move her back and runs and starts good. I think it has a lot to do with Bad valve seals, bad IP and, may be bad rings. I think I will know more when I pull the heads. Move it back to my marks runs good. I got all the sounds you are suppose to hear? Thank you for all the help
     
  12. Macrobb

    Macrobb Full Access Member

    Posts:
    1,261
    Likes Received:
    409
    Joined:
    Jun 12, 2016
    Location:
    North Idaho
    which way did you advance, and what did it sound like?
     
  13. chillman88

    chillman88 Supporting Member Supporting Member

    Posts:
    784
    Likes Received:
    264
    Joined:
    Feb 22, 2017
    Location:
    Central NY
    Believe it or not, my truck was so far retarded that I lost power advancing it that little too. Truthfully I had to advance mine all the way to get it close enough. It was fully retarded when I bought it. She's old and tired but I can't swing a new pump and injectors yet.
     
  14. Joseph Davis

    Joseph Davis Full Access Member

    Posts:
    108
    Likes Received:
    8
    Joined:
    Nov 23, 2017
    Location:
    Lompoc, CA
    more rattle when you first start when cold, when she warms up idle with less rattle. the truck has a lot of power can power break the tires no problem where the timing is set. I move Quarter thickness no tire spin. Same pinning noise but with 50 less on RPM. I order a timing meter and when it get here I can tell you where the timing is at.
     
  15. Macrobb

    Macrobb Full Access Member

    Posts:
    1,261
    Likes Received:
    409
    Joined:
    Jun 12, 2016
    Location:
    North Idaho
    Eh, that sounds right... might have a leaky injector then? (Timing is "off" for one cylinder)
     

Share This Page