M818 Questions From New Member

[Joethemechanic]

Hi My name is Joe and I have a small trucking company. I do a lot of work on construction sites and was looking to buy a M818 to use for a jockey tractor on site. I don't know much about them and I am hoping to find out what to look for when I buy one.

The first thing I was wondering about is the air over hydraulic brake setup. How well do they work? Or should I figure on finding a set of S-Cam brakes that will fit?

I see mention of a late, and an early power steering system. How do I identify them and is one better than the other?

I see a couple of different manufacturers. Are the trucks basically the same? Do the parts swap? Is there any reason to look for one built by a specific manufacturer?

Keep in mind that I want a truck to use on muddy job sites. And I'm probably going to scratch and ding it up a bit. Being historically accurate and a desirable model for a collector is less important to me than availability of parts and reliability of the tractor.

Any help would be appreciated because at the present moment I am lost as all h*ll

 

[papercu]

M818

Hi Joe Welcome!
Brakes are fine for that truck and are designed that way so the military does not need to worry about the trailer brakes being locked down when it's time to "bug out". I'm for any improvements that makes them stop faster, though.
I'm not sure about the PS, it was improved from the M809 to the M939 Series.
Trucks are the same and made that way for the parts to interchange.
Great for the mud.
The bad things for you as I see it.
They are large so maybe not useful for small job sites and the job super may not like those deep ruts when he hit them with his golf cart.
Most mechanics will just scratch their head, if it needs working on, plenty of parts for them but nothing may be close, if you need it in a hurry.
They are 24 volts systems your trailers may be 12 volts no big deal on the job unless you will use it to move from job to job. Good luck. Wayne

 

[Joethemechanic]

RE: M818

Thanks Papercu,

I thought about those down sides to using one and really they are not an issue to me. What I am using now (LTL9000 with full locking rears) and towing/pushing with a D5G Cat leaves a few ruts too and the super just seems happy that the trailers are getting there.

I'm the Mechanic and I am so used to working on strange stuff that I would feel funny working on something routine lol. One thing I do like is that they use 855 Cummins power. I have been working on them for years.

I was thinking about the 24 volt thing. Really I don't need lights but if I do I guess I could come up with something to supply 12 volts to the trailer light plug. I was thinking I could build a simple inverterand then use a step down transformer to get down to 12 volts. Then use either relays or SCRs to control the lights. Not like I can't use 12 volt AC to power trailer lights. Whatever it is I will come up with something if need be.

One other thing I was wondering about is this SF97 thing. I was reading through the forum and saw some mention of having a hard time getting one from govliquidation. What is the problem?
In my state in order to title one, I need a court order from my local JP and I would like to have the SF97 to show him along with the bill of sale.

Thanks again and any help will be appreciated.

 

[imported_Squirt-Truck]

RE: M818

Joe,
The brakes will be just fine as PAPERCU indicated. (That is itself is a seriously mis-understood item.) They will need to be maintained and the adjustment is a little more than adjusting slacks.
The power steering, well, the "old" style is a Ross Hydrapower, spool valve and power pack is all at the bos and the pack operates the box from an attached cylinder. Plenty of power, but requires more sttteng effort and really loads the steeering components. The "new" style is the improved ROss (generally) unit with integral power box like most newer trucks but with a slave cylinder on the right. Like commercial off road setup. This unit actually steers totally hydraulic and has very light wheel feel, if youout run the pump then you will bump the sctor and the force increases. This unid does not load the connectins as bac due to the assistance from th slave.
All the 800 series will be the same regardless of the manufacturer name, same specification. They have the big Cummins N14 small cam at ~240 Hp and lots of torque.

Hope this helps

 

[Joethemechanic]

Yeah that Cummins was a good strong reliable piece. Make a lot more HP and Torque if you change the button to one a few numbers smaller. Here are some instructions I wrote on another site for a guy with a small cam in an early 60's Pete.

This is what your PT pump looks like inside.

To turn up your fuel (power) you need to change the button (part in red) to one with a lower number.

To do this you need to remove the 4 bolts holding the cover on. they are located where I drew the orange lines. If you are careful taking the cover off most times you can re-use the gasket.

The purple tube will have an internal snap ring in it where I colored it blue. Remove the snap ring and there will be a spring retainer, some shims and a spring that will come out. The combination of shims and spring are what sets your High Idle (upper rpm limit). More shims or a stronger spring raises the RPMs. Don't lose any.

Now slide the blue plunger with the green screw (low idle adjustment) in it out of the purple tube. Along with it will come the idle spring, and the BUTTON (red thing)

The button will slide right out of the blue plunger. Be careful not to lose the idle spring. Replace the button with one with a lower number and then reverse the steps to reassemble.

You might have to readjust the low idle by taking the pipe plug out of the cover and turning the green screw. Most times you don't have to though.

How many numbers to drop???????

Good question, Being that you never did one before try dropping 5 numbers at a time until you get it where you want it. Buttons are cheap. Just don't go crazy. when the injector has to inject more fuel, it puts a higher load on the cam, cam followers, push rods and rockers for the injectors. This can cause any of these parts to wear out faster than normal.

But really don't worry about going 5 or 10 numbers lower. We used to run them like that all the time.

I take it you have already cleaned the filter screen in the top of the pump. If not do so. Probably a good time to adjust the overhead too

 

[DaveP]

we raised the fuel pressure on my 250 and it runs the exhaust temp way up. no trouble to get it to 1200 ! i think the lack of piston squirters is mostly to blame.