Detroit 12.7 care and maintenance

[Chamberpains]

Well, I can tell you that probably all the brake valves have been neglected and probably ALL need replaced. The brakes will get spongey. Also the tredle valve is a very neglected part under the brake pedal.

Check the trailer pigtail connection in the driver side box. The wiring corrodes under the rubber grommet inside the cab. Causing all kinds of lighting and weird wiring problems. Including ignition back feeding and light and dash coming on with the key out and fuses pulled.

Being a 60 series you'll want to watch the main ECM harness that goes around the back of the block. They are well known to rub the wires through at the back corners of the engine (more the drivers side but can happen on both side). Also 60 series are well known to break the valve rocker buttons and cages off under the valve cover. Get used to pulling the valve cover when you hear it ticking. You'll be replacing them enough to get good at doing it. Yes even the upgraded ones come apart.

If your cab suspension is needing repair, International sells the entire bolt in suspension unit for about the price of piecing them out and it waaaay easier to replace that way.

The rear axle torsion bars may look good but if the rubber is showing signs of weakness or wear then just replace them. They cause a lot of axle movement and funny drive tire wear. Along with wheel bearings for proper torque and keep good condition shocks on it. They are fantastic suspensions vehicles until they aren't. Then they chew things up quick.

The year you have had a problem with the way the clutch pedal shaft goes through the firewall. It would literally break apart and the small shaft that goes through would bind, not allowing the pedal to be pushed in. Checked it to make sure its in good condition or has been properly repaired. Its a crap job to do but is necessary.

Watch dumping the hood over and letting the hood slam open. Its tied to the top of the radiator and will crack and break the AC condensor, CAC and even the Radiator. Those hood helper springs can be found from Dorman. They are way cheaper than International and last just as long.

Check your firewall starter solenoid on the passenger side. If you're starter is in good shape but the ignition clicks with out turning over, your problem is more than likely there. Don't go cheap buy the good International brand solenoid. All the other ones are exactly that. Cheap crap and fail constantly even right out the box.

Have your drive shafts take down and spin balanced. You'd be surprised the night and day difference in properly balanced straight shafts. They'll easily give you 500k problem free miles including input and output shaft seals and the actual rears themselves get longevity.

Seal up the battery box to keep dirt and dust out. These trucks love to corrode batteries. And like Waterloo said those ECM feed wires rub anywhere all up along the driverside frame rail. Any hints of a problem and just cut off what you can see and run new wires all the way up.

Watch your AC compressor mounting bolts. Detroit did make a good upgraded mounting bracket and your may have it but if it has the old late 90's style then it will come loose and the bolts will wear through the front gear case.

If it was over hauled, did they do the front bull gear in the gear case? If not you'll definitely want to do this. It will absolutely be a ticking time bomb to destroying the engine if hasn't been replaced yet.

I'm sure there's more but this is quite a list. They are great trucks. And you can consistently get 7+ and 8's mpg all day long if you learn to drive them correctly. Read about hypermiling techniques on here and you get good tips. Stay off the car sites to learn about it. They're completley retarded about all of it)

And yes, I worked on these trucks for a few years and then I own and drive 2006 9400i for 5+ years now. There is nothing I haven't torn apart on them.