MaxxForce Diesel Engine Troubles and Solutions

Mechanics Hub Forums Diesel Engines International (Navistar) MaxxForce Diesel Engine Troubles and Solutions

This topic contains 64 replies, has 1 voice, and was last updated by  Angel 1 month ago.

Viewing 15 posts - 1 through 15 (of 66 total)
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  • #44612 Reply

    John Whelan

    I want to reach out to all of you MaxxForce diesel engine owner operators and fleet operators. If you’ve been running these models for any length of time you know that the emission system has many faults. In my situation with our school bus fleet we have medium duty DT and 7 models. Out of the 10 DT models purchased in 2010 – 2011 four of them have required overhauls.

    This is caused by failed EGR coolers that leak coolant into the engine oil causing severe cylinder wear and massive blow by. Way back in time the original DT466 mechanical engine was an excellent medium duty diesel but unfortunately with EPA controlling engine manufacturers to reduce emissions Navistar was forced to push out an EGR controlled engine that could not keep up and sustain reliability.

    Meanwhile Cummins is the leader right now with SCR technology to keep up with EPA demands. Our fleet started buying ISB diesels in 2014 and the turnaround with dependability has been amazing.

    The DT engines in our fleet are constantly breaking down with poorly designed EGR coolers that we monitor with engine oil samples looking at sodium and potassium levels. Once they are over a certain level we immediately test and replace the cooler. They are only available from the dealer $2100.00 which a 500.00 increase from a year ago.

    This is more economical compared to an overhaul (our fourth one is costing up to $9000.00 in parts…EGR cooler, DPF $2400.00, Inframe Rebuild Kit $3800.00, Cyl. Head rebuild (requires valve grind) $800.00 and all of the additional gaskets/seals (before tax). Our shop labor is Mechanic wages and I really feel for owner operators who have to pay truck shop door rates. We’ve also had injector and sensor failures along with the fuel injection high pressure oil systems leaking down.

    So the only way to win against this boondoggle is to fight back with shared knowledge here at this forum. Knowledge and experience is by far the best advantage to keep these gross expenses to a minimum. So if you have anything going on post it here and I will help out the best I can and I hope anyone else reading the posts will chime in and help as well.

    If you have a DT MaxxForce I strongly advise you to take oil samples and get them tested even if you have to mail them or courier them out of town it’s well worth it. The consequences are huge if you’re losing coolant and can’t find an external leak….. that’s a sure sign trouble is brewing. Also check your engine crankcase breather down pipe for oil dripping on to the frame and extra crankcase gases spewing out. You’ll definitely smell it. So don’t hesitate… post here and I’ll keep my eyes peeled šŸ™‚

    #44613 Reply

    John Whelan

    I need to add this: If you still have one of these engines under warranty with the symptoms noted in my previous post go to your dealer and ask them to do a cylinder compression test. It takes 5 minutes using the diagnostic software. Keep track of your warranty and when it expires if you’re over by a week you’ll be out of luck. One of our engines was over by 2 months and all we got back from Navistar was the cost of the piston and liner that had no compression. This was supposed to be a policy warranty that backfired on us. The labor and parts bill was through the roof šŸ™

    #44617 Reply

    John Whelan

    Our current MaxxForce rebuild is coming along. The head is on and torqued down after the required valve grinding job was completed. The twin turbo was rebuilt and injectors tested.

    We have another MaxxForce 2010 that quit on us during it`s morning run. We made a service call and hooked up the laptop and found out there was maybe 10 psi of injection control pressure (800 psi required to run). It got towed up and pushed into the shop.

    On the 27th after boxing day we will be checking the high pressure oil side at the head with a fitting assy. we made up that bypasses the high press oil pump. The oil feed line to the head will get full shop air pressure 120 psi to find out if there are any leaks at the injectors or high press manifold. I`ll keep updating here and probably make a video then post the link.

    It`s Friday and Christmas is just around the corner. I want to extend best wishes to all of you hard working techs. Whatever your chosen field there will always be difficulties because as we all know anything mechanical does not last forever. Good luck with all of your challenges ahead.

    #45586 Reply

    Carlos Rivera

    Did navistar fix all the bugs on the maxxforce?? Or did they quick on this engine and move on with the newer ones? I want to know if there are reliable parts available now for the maxxforce?? Thanks

    #47530 Reply


    I too am having difficulties with my Maxcforce 7.

    #47872 Reply

    Adam Shillingburg

    I’m having issues migh my 2014 maxxforce 7. Curious if anyone has ever contacted an attorney regarding these engine issues??

    #47873 Reply

    Adam Shillingburg

    Correction: 2013

    #48264 Reply


    Was looking to purchase a 2013 model. They said this model has all the upgrades other than the scr. Any advice?

    #48690 Reply


    I have 2013 maxxforce 13, the engine has a miss ,dealer says #6 injector is out of spec, and cylinder 6 has significantly lower compression than the other 5, any suggestions??

    #48786 Reply

    Tyshawn Minor

    I have a fresh overhauled n13 2014 international prostar. Just released from the shop yesterday and it’s leaking coolant to the point where I have a red stop engine light. ???

    #48808 Reply


    There are no updated or re-engineered parts for both MaxxForce engines. The same parts that fail are available but pricey. We have been doing earlier oil changes to keep the oil clean and keeping the RPMs up as much as possible. Another move we made was to turn these buses into spare units to reduce mileage and less problems.

    #48809 Reply


    To answer the second part of your question Navistar have discontinued manufacturing the MaxxForce 7, 9 and 10 including the MaxxForce DT due to the inability to meet emissions. All Navistar school buses now come with a Cummins ISB.

    #48810 Reply


    There is a class action law suit against Navistar for all the troubles going on but this process is going slowly. Check out this link
    Navistar class action law suits

    #48811 Reply


    What kind of upgrades? I’ve never heard of any. Navistar never went the SCR route like Cummins and tried to increase EGR flow. The EGR cooler is a huge monstrosity that costs 1800 Canadian dollars (before tax). These fail constantly along with the diesel particulate filter at 2,000 bucks and the list goes on. I would think twice about purchasing a MaxxForce.

    #48812 Reply


    #6 cylinder on 4 of our MaxxForce DT diesels had no compression and had to be in-framed. Four of our MaxxForce 7 diesel were replaced as well. Unfortunately there’s no other way to go unless you trade it in and go Cummins. We now only buy the ISB for our fleet and the difference in performance is amazing.

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