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c-mac

Porch Pup
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About c-mac

  • Rank
    Old Iron Expert

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  • Location
    louisiana
  • Interests
    many

Previous Fields

  • Make
    mack
  • Model
    chu
  • Year
    2007
  • Other Trucks
    none

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  1. Gonna pull the injectors Monday. I guess if it has stainless, I’ll change just the cups. If there copper I’ll put in a six pack. The engine runs fine other than on cold start it has a little rough idle for about three seconds which my be a little coolant in the suspect cylinder
  2. It’s black and the tank is new
  3. ok the cooler took care of the one I posed the pick of. The next one has a new cooler and compressor. I guess someone else has been chasing this problem too. I checked the newish cooler, it was clean and dry. I clamped pinch off the coolant line to the compress and ran the engine at 1000rpm. The cooling system got up to 13psi. I left the system a little low of coolant so as not to blow it back out. I pulled the overflow hose up and stuck it down a bottle of water and light bubbles were present and the coolant tube from the back of the thermostat housing to the coolant tank was jumping. I cant thing of any other way of determining if it is cups or a head problem. This one is an 08 model built date is 11/07. Not sure if it has copper or stainless cups of if they have been changed
  4. Ok I pulled the cooler because I seen what looks like tiny red droplets of coolant and the inside of the housing is damp and sooty. I’m not sure if what appears to be red droplets is coolant. What do y’all think? You may need to blow up the pic to see
  5. I edited my post. It’s a 12 model and I have an 08 with the same problem. I’m not sure if either has had the cups and injectors replaced. I work on a large fleet and they don’t keep good records..(oilfield). My self I write on the date and hours on the valve cover. I thought I had seen all the symptoms til now.
  6. I’ve got Mack chi 613 with an mp8 that’s blowing coolant out the overflow hose of the coolant tank mounted above the radiator. I’ve already pinched off the coolant lines to the compressor and it builds up to 15 psi in the tank. Is there anything other than a head or head gasket problem that will cause this?
  7. Put a new 7th injector on and took care of the problem. thanks
  8. I just cleaned the Tee on top of the seventh injector where the air and the fuel connect. Now its been on regen 45 mins and only reaching 768deg on outlet temp and the fuel pressures are both steady at around 68psi. and 12% duty cycle. Theses numbers have been the same for 10 mins. The adaptive factor is holding and 1000. I would think it should rise if the temps were not coming up.
  9. Turned out to be the “dump” valve on the trailers air tank.
  10. Dang! Thought someone would have seen this.
  11. Got a 2012 chu613 that when you set the trailer brakes air blows out the yellow exhaust line on the firewall for several seconds then the trailer brakes pop. Air continues to vent at the firewall for a while. I’ve been working on a large fleet of these and I remember having this problem a long while back but can’t remember what it took to fix it. Oh and also the tractor park brake don’t apply until a lot of air escapes. So when you pull both brake buttons air rushes out the firewall vent lines for several seconds until you here a dump at the trailer then all brakes apply
  12. I have a 2012 chu613 MP8 that as the duty cycle gets to 10% or so, the A'treatment fuel pressure drops from 8 to 15 psi under engine fuel pressure which is running in the upper 60's. The exhaust temps never get higher than 750deg or so and wont complete the regeneration. This particular unit has a 7th injector with the "T" fitting on top where the air and fuel lines connect. Just wondering if any of you have seen this and what you've done to correct it. I thinking it could be either the 7th injector, the shut off valve or the T fitting on top of the 7th injector. I've been working on a large fleet of these trucks from 08 t0 13 models for 8 years and haven't ran into this before.
  13. c-mac

    2008 mp8 falls on its face

    I have had the problem you've described that was a bad engine ECU but it always set a trouble code.
  14. OK, I"m kinda embarrassed to say I think I have figured it out. when I started the engine cold it stumbled for a second which seemed odd, the oil pressure looked good 45 idle and 75 running high, then started dropping back to what it was prior to attempted repair. To make a long story short, fuel is getting into the oil ..how? past a bad injector oring? Thats all I can come up with anyway. I work on a fleet of 150 2008 and up macks eveyday and haven't ran into this problem. I've had fuel in the coolant several times, but not this. This engine has had cups and injectors about 1000 hours back. Do you think I can get away with just injector orings or maybe ya'll know of something else that may be the problem?
  15. looked ok about to go back with all new orings, thanks

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