Tool truck project

[Wrench]

Got a new project lately. It is a 1993 Isuzu NRR cabover with a 16' box on the back, garage doors on the rear and right side. I am going to be using this as a mobile "tool box" with a few RV type amenities installed.

Engine: Isuzu 6BG1T 6.4L turbo diesel, runs real good.
Transmission: Allison AT542

Anyone here have any experience with these transmissions? Seems to shift just fine at WOT but not at part throttle (wont shift at low enough rpm). I have done a complete pan/auxiliary filter service, adjusted the throttle modulator cable per the manual, and checked the governor, but still acting the same.

[kenny24]

I am no expert on this but some of the allison don't like to shift at lower RPMs. Here is a trouble shooter link for allison transmisions http://allisontransmissionparts.com/All ... rts-A.html

[Wrench]

Yeah, that is the exact same chart that is in my trucks service manual. I have checked pretty much everything on the list, but still not getting anywhere.

I guess I'll order the proper Allison Service Manual.

[kenny24]

We have a great diesel mechanic at work. I'll ask him on Monday a see what he says

[Wrench]

I decided to go out on a limb and just play with the throttle input to the trans. Made a big difference! It's quite a bit off of the "stock" setting, though.

I just LOVE this truck! The engine is all mechanical, so tweaking it for performance is as simple as turning adjustments and watching the EGT. It is also a sleeved block and extremely common, so rebuilds are cheap and you can do them with the engine IN the frame.

Here is the plan: This truck is being set up for Mobile Maintenance. I plan to have an air compressor, generator, welder, and propane system on board. When it is done, I hope to use it on the occasional Jeepin' trip and just flat-tow the Cherokee behind it. Funny thing is, these things usually get about 13mpg fully loaded, which is the average fuel economy I get with my Cherokee anyway!

I'll get some pics up soon. I got a new laptop lately and finally figured everything out to sync it with my phone.

[TJDave]

Mobile maintenance? Like RV's? That would be

[Wrench]

Mobile maintenance? Like RV's? That would be

[Danny]

Paul, that would be cool. R there any others in the TC or are U going to be the first?

[Wrench]

Paul, that would be cool. R there any others in the TC or are U going to be the first?

"Reliable RV" is in Kennewick. At least that is what the Directory says.

[kenny24]

How is the transmission running..got some info on it if you still need it.

[Wrench]

I'll take any info I can get!

I have the cable adjusted a ways from the stock setting and it seems to be working pretty well. It may just be masking a problem, though.

[kenny24]

What I got from our mechanic is the installation instructions from Morse for the AMII Modulator Control Valve and Tech sheet from Allison for Installation Procedures. He also gave me his final test sheet with settings for the MT 654CR transmission for a reference sheet. Just need to know how to get it to you.

[Wrench]

Sooo...

I got laid off just over a week ago. Work on the airplanes is really dying off. Darned economy...

So now I guess posting this wont compromise anything:

[TJDave]

Cool. I have a couple issues.



Of coarse, anyone who has met me knows that already!



Not cool that you were laid off though. Sorry to hear that.

[79chevy39.5's]

today was my first day as the isuzu tech at mccurly if any other issues arrise

[Wrench]

today was my first day as the isuzu tech at mccurly if any other issues arrise

I have concluded that the centrifugal governor in the trans is probably worn out. The book tells me to measure the opening on the shaft with the weights extended, but it seems pretty vague as to whether that is a min or max measurement.

[79chevy39.5's]

.51mm min

[Wrench]

I did a pan filter and aux filter change, but may have missed what was referred to as the governor filter/screen. Where is that? Cant find any pics or data on it.

My governor shaft gap is well over the minimum.

[79chevy39.5's]

does your truck have the allison? the only info i have on these older trucks refers to the allison even though there is a frx or fmx trans in the one im currently working on (1990)

[Wrench]

Allison AT542.

And I really need a Tach. I think the torque converter is slipping, but I dont have a tach to see for sure. How do you add a tach to an older diesel like this?

[79chevy39.5's]

no information on gov. screen? maybe a specific allison trans book may have someting more detailed, as for a tach i dont remember seeing anything on the pump of the truck that i worked on similar to yours but there are copanys that make diesel specific aftermarket tachs using a reflective tape i believe

[79chevy39.5's]

or somethin off a tach

[Wrench]

Check out this link:
http://www.allisontransmission.com/docu ... 1321EN.pdf

On page 7 it states this:

• Remove, clean, and reinstall the governor feed line screen in the control valve body.

I could not find that screen, and cannot find any tech data on where it is located. If you can, that would be a great help!

[Wrench]

Fuggit, looks like my help left...

I pulled the governor, stretched the springs a tad to give them more tension, and welded on it a little to add weight.

She shifts "normal" now without revving so high and much smoother. I think I picked up at least .5-1 mpg.

On that subject, I have a little info to share: I began using a diesel additive about a month ago. It is highly concentrated and you only need about 1 oz for 39 gallons. I religiously document my fuel mileage and have a solid .7mpg increase over the last 800 miles using this stuff. I was only getting 9.2 mpg before, so that is about an 8% increase. It more than pays for itself with the fuel savings.

[79chevy39.5's]

i dont have specific info on allisons, kennworth out in king city is an Allison dealer...we only have Jatco information