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Mackpro

Pedigreed Bulldog
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Posts posted by Mackpro

  1. If an MP8 then you can easily pull the elbow and hose off the EGR cooler outlet ( towards the front of the truck) and look directly into the EGR cooler and look fir dried and crusty antifreeze. MP7’s are harder to do because you can’t get the EGR cooler outlet pipe out of the way with out pulling the fan clutch to look inside the EGR cooler. There is a radiator pressure cap on the left side ( not the right side)  of the coolant expansion tank on top off the radiator . It has a small overflow drain hose on it . If the cap is blue it needs the new black cap on it . If it has the black cap , get a 1 liter clean Sprite bottle and put the end of the hose in the bottle ans zip tie it up and run the truck for a day  . See if it’s actually blowing the coolant out or burning it, 

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  2. The local Kenan gas tanker trucks had those transmissions in them many many years ago. I went on many late night service calls due to the drivers leaning over on the gear shifter and the shifter would pop out of the slot for the shifter fork. We finally found out if we left the gasket out and just used RVT/silicone the shifter would stick down in the top cover just far enough to keep this from reoccurring. 

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  3. Lots of items have been dropped from the extended warranty plans. We max out the extended warranty on the trucks here and things that used to be covered in our 2016 extended warranty plans are no longer covered in our 2021 plans. Sometimes the salesmen dont not go over the fine print  on the extend warranty. 

     

  4. 2004 was the first year and only year for they crammed  Aset AC engine in the CH/CX the results were not good . Lots of over heating issues, we were changing fan belts every oil change due to the under hood heat causing belt failure. Things eventually got sorted out with parts updates and service campaigns/recalls. By 2005 the CHN/CXN came out and problems decreased. I do remember seeing the fan clutch surging you described but don’t remember the cause or repair. The fan clutch used on the ASET AC look exactly the same but are different part numbers, so the incorrect one could be installed. Troubleshoot on the fan clutch https://pdf4pro.com/cdn/service-bulletin-mckenzie-tank-lines-a3dd0.pdf

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  5. There was an older service bulletin on the 4094 that was very helpful but I don’t have it with me. Something often over looked is the EGR system, mainly the EGR differential  pressure sensor and it’s common problem of port clogging. There are updates for the MP7 venture pipe, tubes and sensor. When the ports clog the Engine ecm sees low EGR flow and commands the EGR valve to open more and  can cause the 4094 code. DEF usage and dosing percentage varies based on engine load and other factors so don’t look to much into that. Also on pre-OBD ( 9 pin diag connector) I was told by Mack Tech Support that the nox readings  that you see might not be always what the actual readings are and what the ACM actually sees. Also the exhaust stack outlet should be clean with no soot or darkness. Any soot passing the DPF will cause high NOx . The pre-OBD 4094 and the 2013+OBD  P20EE00 codes are pretty much the same. Which is their way of saying “ You got high NOX and we don’t know why and you figure it out”. Usually on OBD trucks the the outlet nox will be 1/3 of the inlet when dosing. Message me your email and I’ll see what bulletins I can find to send you. 

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  6. In the PI,AN and GR’s (Pinnacle  , Athem and new stlye Granite  ) they now have the light control module LCM that controls all the lights. In the fuse box on top of the dash , check all fuses labeled LCM There could be as many as 7. These trucks now have 2 separate hood harnesses one for the right side and one fir the left. I have see a few passengers side Athem harnesses rubbing and shorting just behind the connector at the hood on the chassis side of the connector. 

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