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d 8n

Discussion in 'Dozers' started by burns, Dec 10, 2018.

  1. burns

    burns Active Member

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    does anyone have the engine hi idle specs for a d8n with a 3406 in it
    regards
     
  2. Nige

    Nige Senior Member

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    Tractor (or even better - engine) Serial Number...?
     
  3. thepumpguysc

    thepumpguysc Senior Member

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    The 3406 went in 1000.s of diff. machines.. The speed could be anywhere from 1800-2600.. or higher.
    GOTTA HAVE a SN..
     
  4. Shimmy1

    Shimmy1 Senior Member

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    What are you attempting to do that you need to know this? Only reason I ask is if you're diagnosing operational issues, that's fine. If you're digging around in the fuel pump, there might be other pertinent info you should have, and without knowing that fact the guys might not share something important.
     
  5. thepumpguysc

    thepumpguysc Senior Member

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    Turn it no higher than 2600 "no-load" & expect a 10% drop in rpms when its working.. THATS how its designed.. IF it drops lower than around 10% u have an issue..
    ..could be a fuel "supply".. or a governor issue.. or your doing something w/ the machine its not designed to do..??
     
  6. Tinkerer

    Tinkerer Senior Member

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    A badly adjusted decelerator linkage will cause a decrease in high idle rpms.
     
  7. Bluox

    Bluox Senior Member

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    I think you better check your book, 3406 is almost all 2100 high idle although some fire pumps could go 2300.
    Bob
     
    StanRUS likes this.
  8. burns

    burns Active Member

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    9tc is the tractor 70v25461 is the engine, customer bought this machine 12 months ago and the engine gradually gets hot and so the transmission gets hot aswell on a 30 degree celcius day and above. seems to take a over 10 mins for it to gradually get temp down to say 85 degrees on engine 95 transmission. water pumps been replaced , thermostat, fan pulleys, radiator, coolers cleaned, im just wondering if the high idle is incorrect and not having enough revs. this machine has done it since his bought it
    regards
     
  9. Shimmy1

    Shimmy1 Senior Member

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    Keeping anything with a little age on it cool is a challenge in hot weather, 30°C is 90°F, that is damn hot for a tractor that size. Is the operator an experienced one? If he's working the snot out of it, it might just be the way it is.
     
  10. Nige

    Nige Senior Member

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    Machine S/N is 9TC01550. Dates from October 1987. Not new, or even new-ish ........

    Is that 10 mins to cool down to 85DegC coolant temp with the transmission in neutral and the engine at somewhere close to High Idle..?
    Belly guards all nicely cleaned out..?
    Does it black smoke when working hard..?
    How many hours on the engine & radiator since the last rebuild..?
    The list of parts you posted that have been replaced. Genuine Cat parts used, 2nd hand parts, or "will fit"..?
    Coolers cleaned..? What happened to need coolers cleaned.. ? Trans or TC failure..? I'm not a fan of cleaning coolers, prefer to replace them.
    Any chance it could have something like a wrong turbo or wrong injectors (or both) in it..?
    Has anyone tried using an infra-red gun to take the temperature of the hose going into the top of the radiator and the one going out at the bottom to check radiator efficiency..?

    Test Spec for 70V25461 is 0T-6736. High Idle No Load 2225-2345 RPM. Governor setting speed 2148-2158 RPM. Full Load Speed 2090-2110 RPM. Low Idle 740-760 RPM. PM me with an email address if you want the full test spec including governor settings. It's too big to post here.
     
    Last edited: Dec 10, 2018
  11. Cmark

    Cmark Senior Member

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    Can I just add that high idle isn't really measured or adjusted when carrying out governor settings. Note the large range in Niges high idle spec above compared to the governor setting speed, FLS and FTS specs which are very narrow and critical.
     
  12. burns

    burns Active Member

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    3o deg is not hot where im from experienced dozer driver always pushing in first, radiator replaced, transmission failed 12 months ago did a clutch pack, cleaned all system out then replaced trans scavage pump, t/c converter was changed three weeks ago to get on top of issues, dont have any info on engine engine is clean when pushing under load, im trying to narrow down issue thinking that if its not reving hi enough creating a stall when pushing. i put my infa red gun on back of transmission housing it reads 80 degrees then i put it on outlet of t/c where sensor is and it reads 120degrees celcius im thinking that that is normal temp vaue after load from t/c. the sensor and guages have been changed aswell sent a video of machine puhing to a fellow that has one and he said it should push all day like this in first gear
     
  13. burns

    burns Active Member

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    belly guards clean even took side engine doors off to see if would make a difference advised operator to put in neutral and have sitting at about 1500 rpm ive done more on d10t and they cool a hell of a lot quicker but realise all machines are different
    radiator efficency good 10 degrees drop
     
  14. Shimmy1

    Shimmy1 Senior Member

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    I don't know if this is pertinent, but I used to work with a 7H that struggled to cool. After studying the service manual for about a day, and figuring out how the oil flows worked, I decided I needed to check the T/C outlet pressure, and discovered it was out of spec by a small amount. This was over 15 years ago, but if I remember correctly the spec was around 75ish psi, and I was under the minimum spec by around 5 psi. Having tried everything else, I figured out that t/c outlet pressure was controlled by a spool in the control valve on top of the transmission, and decided to pull the valve block and completely disassemble it. When I got to the outlet spool, I found probably the smallest little black particle you could see with normal eyesight in a spot where it could possibly float around and block a small orifice. Put it all back together, cooling issue solved. Not saying this is your problem, but I think you're going to need to get some gauges on this tractor and make sure things are working right. 120°C sounds pretty close to the limit of what I'd consider acceptable for max temp.
     
  15. burns

    burns Active Member

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    Tc inlet pressure is in control valve it was rebuilt at transmission rebuild i put new outllet valve and spring in when t/c rebuild all within spec
     
  16. Shimmy1

    Shimmy1 Senior Member

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    Have you checked outlet pressure while it's working? That's what I had to do.
     
  17. thepumpguysc

    thepumpguysc Senior Member

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    Dam.. I just reread my post.. whoops.. I "mis-spoke".. sorry bout that.. my finger went UP when it shoulda went OVER.. :(
     
  18. Cmark

    Cmark Senior Member

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    Can you elaborate on what's been done to the radiator? If it's original, you have a folded core type. They were never a great design with very narrow tubes which will block up at the drop of a hat.
     
  19. Nige

    Nige Senior Member

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    Was the trans cooler replaced when the tranny was done 12 months ago..?

    If it hits the alarm on TC out temp and you stick it in neutral @ high idle the TC out temp should fall like a stone. If it doesn’t I’d say you have issues in the cooler, which is where we came in.......
     
  20. burns

    burns Active Member

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    radiator has all complete new cores, t/c out temp does not fall like a stone, neither does the coolant temp, i pulled the cooler because i thought id found the cooling issue with the aluminium backing plate of water pump all corroded, so i pulled cooler thinking aluminium blocking holes, i rodded holes and flushed out oil side to get any possible dirty material out from transmission.
    im getting temp differences of 15 degrees from both oil sides of cooler, so cooler never replaced