Mechanical Genius

[daniel ruops]

My wife and I own a Expedition Camper. The truck is a Mitsubishi Fuso FM 260. The four wheel drive was installed by Marmon Harrington in Kentucky.
Unfortunately for us, a design flaw in the drivetrain resulted in serious and ongoing problems for us with huge consequences and cost.

W.W. Williams of Nevada, Diesel Specialists of Nevada, Wise-Mack of Nebraska, Interstate Power Systems of Iowa and Valley Power Systems of Ca. all were helpful in correcting specific repair events however none of the above companies properly diagnosed, identified and corrected the design flaw which caused each event.

Mitsubishi of San Diego referred us to Ferguson Truck Body and Equipment 383 North Johnson Ave, El Cajon, Ca. Eric Ferguson is a mechanical genius who resolved our problem. I strongly recommend Eric to Portal members for repair and customization.

 

[mog]

My wife and I own a Expedition Camper. The truck is a Mitsubishi Fuso FM 260. The four wheel drive was installed by Marmon Harrington in Kentucky.
Unfortunately for us, a design flaw in the drivetrain resulted in serious and ongoing problems for us with huge consequences and cost.

Although there are only two of these 4x4 FM260s out in 'the world', I'd be very interested to hear what the problem(s) was/were?
Maybe us with 'baby' Fusos can learn something.

 

[charlieaarons]

yes, please, my curiosity is seriously stimulated. What was the specific symptom and ultimate diagnosis?

Charlie

 

[DzlToy]

factory driveline issue or 4WD conversion issue?

Making a 2wd truck into a 4wd is not an engineering marvel. I am quite surprised to hear that none of the companies you worked with could solve the problem.

Was this one of Darrin's trucks?

 

[JRhetts]

I don't want to step on Dan's thread, but for the obvious reason that I operate the 'sister' truck to his, I had a long conversation with him last evening. I came away with the following points; I sincerely hope he posts back as I may have failed to get things straight, and I hope he will correct any errors I make here.

Yes, DzlToy, both units are "Darren's trucks."

Over a several thousand mile span Dan experienced several different problems associated with the drive train. I regret I did not get clear on the specific symptoms that led to each of the following replacements. If Dan does post again perhaps he will spell out the symptoms. These are what I understood from our conversation:

1. He replaced a seal on the rear diff where the driveshaft enters the diff

2. Sequentially he replaced several of the universal joints — Dan was not sure which ones exactly and in what sequence

3. He replaced a rear seal on the transmission twice

4. He replaced a seal on the transfer case three times

5. Mr Ferguson determined that the "rubber bushings" which mount the transfer case to the frame had become "soft and spongy", allowing the transfer case to "slap around". Marmon-Harrington told Dan that they have been using this design for over 50 years and that it was tried and true. Dan reported to me that Ferguson installed new bushings custom made out of "polyurethane", and he replaced all the U-joints.

6. Dan indicated he believed the general cause of all the problems was excessive vibration, though he said he did not discern this himself at the time.


My Experience

1. I replaced a front shock at ~10,000 mi; Mitsu quickly sent me a new one.

2. I have experienced less than expected fuel economy and [very!] reduced power when pulling hills. Mitsu determined that I was getting at least 6 psi less boost than factory specs. After some 'focussed' conversations Mitsu agreed to install a new Turbo unit; I gained 2 psi and have relented on trying to get "all I deserve."

3. At about 12,000 miles I detected what seemed to be a speed-related vibration. Upon further testing, it turned out it occurred at all speeds when in Neutral. This led to the discovery that one of the U-Joints on the shaft between transfer case and transmission was very sloppy. Upon disassembly, one of the fixed 'ears' had worn extremely and was well on its way to catastrophic failure, which would have caused major damage if the shaft had started flailing away while driving. As best we could do at autopsy, it appeared that either one zerk never got greased after initial installation or the zerk was clogged and no one had noticed that it wasn't actually accepting grease. All has been good here since then.

4. Last summer in the Yukon I suddenly heard an unmuffled exhaust. My exhaust brake had dropped out of the exhaust pipe fitting and was dangling by its air hose connection. Four new bolts and all is well here, too.

 

[SkiFreak]

My exhaust brake had dropped out of the exhaust pipe fitting and was dangling by its air hose connection. Four new bolts and all is well here, too.

A possible solution to this problem is to use anti vibration washers on those exhaust brake bolts. That's what I did after replacing the OEM 2 1/4" retarder with a 3" one.

Unfortunately, standard spring and shake-proof washers are not really suited to this application, as heat over time will remove the "springiness" from these washers.
An alternative is to use Nordlock washers, which is what I used.

 

[JRhetts]

..
An alternative is to use Nordlock washers, which is what I used.

Those look pretty cool. Where do you get them in any reasonable quantity and cost?

 

[SkiFreak]

I can tell you where to get them in Australia, but I have no idea where you would get them in the States.
What diameter and how many bolts are on your exhaust brake?

 

[JRhetts]

What diameter and how many bolts are on your exhaust brake?

10mm x4.

 

[SkiFreak]

I sent you a PM John.