Page 2 of 2 FirstFirst 12
Results 11 to 18 of 18
  1. #11
    Platinum Member
    Join Date
    Mar 2002
    Posts
    513
    Location
    Bolivar, pa.
    Tractor
    power trac 422, and agco-allis 5660, john deere 550 dozer ,1845 power trac

    Default Re: Service bulletin for improving Robin engine starting

    My 422 which is now 12 years old starts without any problems as low as 20 degrees, at lower temperatures I might have to try it several times but it has always started and it still has the original battery and very seldom have I put it on charge.
    Now my 1845 will start at the same temperature ranges but it struggles at the low temperatures and when it does start it idles very roughly for several minutes and smokes a lot.

  2. #12
    Elite Member BobRip's Avatar
    Join Date
    Sep 2004
    Posts
    4,362
    Location
    Powhatan Va.
    Tractor
    2000 Power Trac 422

    Default Re: Service bulletin for improving Robin engine starting

    Quote Originally Posted by ernemats View Post
    My 422 which is now 12 years old starts without any problems as low as 20 degrees, at lower temperatures I might have to try it several times but it has always started and it still has the original battery and very seldom have I put it on charge.
    Now my 1845 will start at the same temperature ranges but it struggles at the low temperatures and when it does start it idles very roughly for several minutes and smokes a lot.
    Any idea what is different about you machine? Yours is about the same age as mine.
    Bob Rip
    Tell me and I will hear.
    Show me and I will see.
    Let me do and I will learn.
    Let me fail and I will understand.

  3. #13
    Platinum Member
    Join Date
    Mar 2002
    Posts
    513
    Location
    Bolivar, pa.
    Tractor
    power trac 422, and agco-allis 5660, john deere 550 dozer ,1845 power trac

    Default Re: Service bulletin for improving Robin engine starting

    I have no idea. Several years after I purchased mine sometimes it was very difficult to start in cold weather, then I changed spark plugs to the ones Jack Robin suggested and that seemed to help.

  4. #14
    Elite Member BobRip's Avatar
    Join Date
    Sep 2004
    Posts
    4,362
    Location
    Powhatan Va.
    Tractor
    2000 Power Trac 422

    Default Re: Service bulletin for improving Robin engine starting

    Quote Originally Posted by ponytug View Post
    I agree. One of the first things that I did after getting my PT was to up the battery cable sizes, and add a central ground point on the engine, with extra ground wires to the front and to the tub itself. I also sanded the ground point on the engine for the best electrical connection. (In hindsight, I probably should have run one over to the ground screw on the the electrical interconnect, but that was before I had taken it apart.)

    As always, YMMV...

    All the best,

    Peter
    In order to get an idea of the losses in the battery cables I measured the voltage drop on the cables while cranking. I then calculated the resistance assuming 90 amps of cranking current. If you have a better number let me know.
    Positive cable. 0.023 volts 0.00253 ohms
    Negative cable. 0.018 volts 0.002 ohms
    Negative cable connection to starter motor. 0.05 volts. 0.0005 ohms.

    The total resistance is 0.005 ohms. This is about 4% of the starter motor resistance. The test was done with the engine warm. During cold weather and a cold engine the starter current will go much higher and the cable losses will increase. With fatter cable the losses could be cut in half. Will it help to use fatter cables? The calculations don't rule that out. I don't plan to do this, but if a cable fails, I will replace it with fatter cables.
    Bob Rip
    Tell me and I will hear.
    Show me and I will see.
    Let me do and I will learn.
    Let me fail and I will understand.

  5. #15
    Platinum Member
    Join Date
    Jan 2005
    Posts
    661
    Location
    SW Virginia
    Tractor
    PT425

    Default Re: Service bulletin for improving Robin engine starting

    Quote Originally Posted by BobRip View Post
    In order to get an idea of the losses in the battery cables I measured the voltage drop on the cables while cranking. I then calculated the resistance assuming 90 amps of cranking current. If you have a better number let me know.
    Positive cable. 0.023 volts 0.00253 ohms
    Negative cable. 0.018 volts 0.002 ohms
    Negative cable connection to starter motor. 0.05 volts. 0.0005 ohms.

    The total resistance is 0.005 ohms. This is about 4% of the starter motor resistance. The test was done with the engine warm. During cold weather and a cold engine the starter current will go much higher and the cable losses will increase. With fatter cable the losses could be cut in half. Will it help to use fatter cables? The calculations don't rule that out. I don't plan to do this, but if a cable fails, I will replace it with fatter cables.
    .02V isn't much voltage drop at all in a starter circuit. On mine, I would expect at least .2V and up to 2.0V in really cold weather when the starter is really working hard.

  6. #16
    Elite Member BobRip's Avatar
    Join Date
    Sep 2004
    Posts
    4,362
    Location
    Powhatan Va.
    Tractor
    2000 Power Trac 422

    Default Re: Service bulletin for improving Robin engine starting

    Quote Originally Posted by Gravy View Post
    .02V isn't much voltage drop at all in a starter circuit. On mine, I would expect at least .2V and up to 2.0V in really cold weather when the starter is really working hard.
    This is just across the wires. The battery voltage will drop as you stated. My experience is that you do the math, but the actual affect is much greater than calculated. We are getting into strange territory. Edison stated that whenever you talk about batteries you are lying. What I think that means is that batteries are too complex in their behavior to describe that behavior and be completely accurate. I have found this statement to be accurate, but I am probably lying.
    Bob Rip
    Tell me and I will hear.
    Show me and I will see.
    Let me do and I will learn.
    Let me fail and I will understand.

  7. #17
    Veteran Member
    Join Date
    Mar 2007
    Posts
    1,364
    Location
    Bay Area, CA
    Tractor
    Power Trac PT1445

    Default Re: Service bulletin for improving Robin engine starting

    Well, it is a 1445, and it starts fine at 40. 35 is getting a bit slow, but it always starts on the first crank. The thick oil in the hydraulic pumps is clearly the issue for the starter. Nonetheless, a glow plug is on my list. I can check the cable size; I think they are 2ga.

    I try to let the machine warm up the hydraulic oil before trying to do much; I'm not wild about having any cavitation in the intake oil filter from the tank.

    All the best,

    Peter


    Quote Originally Posted by BobRip View Post
    How does your machine start below 50 deg and 40?

  8. #18
    Veteran Member
    Join Date
    Mar 2007
    Posts
    1,364
    Location
    Bay Area, CA
    Tractor
    Power Trac PT1445

    Default Re: Service bulletin for improving Robin engine starting

    Dear Bob,

    It is always great to have real numbers! With those sorts of resistance numbers, any gain at all might be solely in the contact resistance at the cable ends. Yet another reason to take them apart every so often and clean them.

    As I said, I did it preemptively, not because I had a problem, but because it had been a common problem for me on other engines. It might be one of those chromed under hood items- looks nice, but not functional... :-)

    Thanks again for measuring!

    All the best,

    Peter

    Quote Originally Posted by BobRip View Post
    In order to get an idea of the losses in the battery cables I measured the voltage drop on the cables while cranking. I then calculated the resistance assuming 90 amps of cranking current. If you have a better number let me know.
    Positive cable. 0.023 volts 0.00253 ohms
    Negative cable. 0.018 volts 0.002 ohms
    Negative cable connection to starter motor. 0.05 volts. 0.0005 ohms.

    The total resistance is 0.005 ohms. This is about 4% of the starter motor resistance. The test was done with the engine warm. During cold weather and a cold engine the starter current will go much higher and the cable losses will increase. With fatter cable the losses could be cut in half. Will it help to use fatter cables? The calculations don't rule that out. I don't plan to do this, but if a cable fails, I will replace it with fatter cables.

Page 2 of 2 FirstFirst 12

Similar Threads

  1. PT-425 Engine Removal Procedure [Long]
    By SnowRidge in forum Power Trac
    Replies: 7
    Last Post: 04-12-2009, 08:20 PM
  2. Kubota Service bulletin
    By JimC in forum Kubota Owning/Operating
    Replies: 1
    Last Post: 07-26-2003, 07:25 PM
  3. Has anyone switched to an electric fan?
    By dgood1 in forum Customization
    Replies: 17
    Last Post: 10-11-2002, 11:59 PM
  4. Engine Oil
    By RoyD in forum Ag Tractors & Machinery
    Replies: 4
    Last Post: 03-13-2001, 08:04 AM
  5. Starting Kubota Engine #2
    By Anonymous Poster in forum Kubota Owning/Operating
    Replies: 6
    Last Post: 05-15-2000, 01:49 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
© 2016 TractorByNet.com. TractorByNet is a registered trademark of IMC Digital Universe, Inc. Other trademarks on this page are the property of their respective owners.