Just won an auction - M1088A1

[dwlindsey]

The site doesn't allow me to send PMs
I guess I am to new here?
Any moderator willing to help me out?

You need a certain number of posts before you can send messages.

I had the same problem, early on.

I'll send you a PM, you can reply to it

 

[Floridianson]

[QUOTE="dwlindsey, post: 2617955, member: 13662 Idon't want to drive it very far until I get grease into all the zerks.
[/QUOTE]
Myself when I got my 1088 I went through all the hubs. One of the rear hubs was missing the thrust washer and thanks member NDT if I remember sent me one free. If you don't have the time to get to the rears the fronts are easy to just drain and refill. Hopefully no metal shavings.

 

[dwlindsey]

The 5th wheel plate came off today

 

[dwlindsey]

The auxiliary transmission cooler came off today. The plumbing seems to have been transmission to primary cooler, primary cooler to valve (thermostat valve?) then back to transmission. The valve has an output to the auxiliary cooler and and return from the Auxiliary cooler. I guess you would call that a secondary loop through the auxiliary cooler.

So it seems to me that when the oil is hot, it's diverted into the auxiliary cooler, back through the valve and back to the transmission.

So what I did today is to cap the ports on that valve that went to and from the auxiliary cooler. With those hoses off, we unbolted the auxiliary cooler and removed it.

If I'm right, with those ports in the valve that went to and from the auxiliary cooler capped off, there should be a loop - transmission to primary cooler, then primary cooler to valve, then valve to transmission. It should work fine. Can someone confirm or deny?

My plan is to get a new hose ASAP to do the return from primary cooler to transmission, which will eliminate the valve (thermostat valve?).

I don't plan to drive it far until I get the new hose, just in and out of the garage, because I can't raise the cab in the garage. Am I OK for short drives of 30 feet, until I get the new hose?

 

[dwlindsey]

The 5th wheel plate weighed in at 1020 pounds. According to the TM it should have been 980. I'm not sure where the extra 40 pounds came from.

The M1088, after 5th wheel plate removal, with auxiliary transmission cooler still attached, was 17,020 pounds. I don't have a weight following the removal of that auxiliary cooler, but the cooler probably weighed 200 pounds, so we're about 16,800, I'm thinking.

Driving it 8 miles round trip today to the scrap yard was interesting. It's the longest drive I've done yet and everything seems to be working OK. I've got some air leaks I need to fix, but the air stayed near 120 PSI for the entire trip,

And the CTIS is working great, using the Christian Platzer CTIS controller. The CTIS is the big reason I wanted one of these trucks, 4x4 or 6x6, instead of a Unimog or other Mercedes chassis. The Mercedes would be more plush, but I want to get out on the sand and manually airing big tires down and up again doesn't appeal

 

[dwlindsey]

The auxiliary transmission cooler came off today. The plumbing seems to have been transmission to primary cooler, primary cooler to valve (thermostat valve?) then back to transmission. The valve has an output to the auxiliary cooler and and return from the Auxiliary cooler. I guess you would call that a secondary loop through the auxiliary cooler.

So it seems to me that when the oil is hot, it's diverted into the auxiliary cooler, back through the valve and back to the transmission.

So what I did today is to cap the ports on that valve that went to and from the auxiliary cooler. With those hoses off, we unbolted the auxiliary cooler and removed it.

If I'm right, with those ports in the valve that went to and from the auxiliary cooler capped off, there should be a loop - transmission to primary cooler, then primary cooler to valve, then valve to transmission. It should work fine. Can someone confirm or deny?

My plan is to get a new hose ASAP to do the return from primary cooler to transmission, which will eliminate the valve (thermostat valve?).

I don't plan to drive it far until I get the new hose, just in and out of the garage, because I can't raise the cab in the garage. Am I OK for short drives of 30 feet, until I get the new hose?

OK, I've figured it out. Nate Volk did an auxiliary transmission cooler delete on his M1088

It's apparent that he took the return hose off of the valve (thermostat valve?) and connected that hose to the elbow that's now on the transmission "to cooler" port. He didn't get a new hose, just re-routed the existing hose.

I'm going to do exactly that. Thanks Nate! Your video was very helpful.

 

[Ronmar]

the thermostatic valve only routes oil to the aux cooler when the temps returning from the primary cooler are warm enough to warrant it. yes, take that thermostat valve out of the system completely with only the transmission to-from ports connecting forward to the primary cooler...

 

[dwlindsey]

I'm making some progress. The fifth wheel plate is off, the auxiliar transmission cooler is off, the work platforms are off and I've painted more on the frame.

I also tracked down and fixed a couple of air leaks today.

Here's the latest picture.



I'll be out of town for a couple of weeks starting tomorrow, I'll start on replacing the air cleaner and getting some primer on the cab in late August or early September

 

[dwlindsey]

I have an air line at the back of the frame on my M1088 that has been disconnectged since I got the truck from GovPlanet. The air line goes to intermediate axle. There's a T that goes through the cross brace to an elbow with a kind of cap that rotates freely.

On the intermediate axle there are two air lines a larger one (the one that's disconnected at the rear of the truck) and a smaller one.

I imagine that the smaller one will lock the two axles together. Correct? What should the large one do? The larger line at the disconnected end has a 45 degree elbow that was obviously connected to something at one time. Where should it go?

I've found the pneumatic schematic in the 34-4 TM, but as far as I can read it, there's only one air line going to the axle. I'm sure I'm reading it wrong, but I'm quite confused.

What does the larger, now disconnected, line do and where should it be connected?


View attachment Air line disconnected at rear of truck.jpg
View attachment Air lines on intermediate axle.jpg

 

[Ronmar]

Well the cap that rotates freely sounds like a vent cap…

Each axle should have a vent line to the top of the axle housing.
There should be the control air line to the power divider on the intermediary axle differential(AWD to 6WD control when mode/6X is selected)

Each end of both axles should have 4 air lines.
One is park air to compress the park springs/release the park brakes.
One is service air to apply the service brakes
One is the service brake vent. Service air is applied to one side of the service diaphragm to apply brakes, the other side of the diaphragm is vented thru this line to atmosphere. The vent line usually only runs up to a pass-thru port on the frame
The last is CTIS to control tire pressure thru the spindle/hub.

If you identify all of these, that may help give you an idea what the line you are talking about is actually for.

 

[dwlindsey]

Well the cap that rotates freely sounds like a vent cap…

Each axle should have a vent line to the top of the axle housing.
There should be the control air line to the power divider on the intermediary axle differential(AWD to 6WD control when mode/6X is selected)

Each end of both axles should have 4 air lines.
One is park air to compress the park springs/release the park brakes.
One is service air to apply the service brakes
One is the service brake vent. Service air is applied to one side of the service diaphragm to apply brakes, the other side of the diaphragm is vented thru this line to atmosphere. The vent line usually only runs up to a pass-thru port on the frame
The last is CTIS to control tire pressure thru the spindle/hub.

If you identify all of these, that may help give you an idea what the line you are talking about is actually for.

 

[dwlindsey]

The brake and CTIS lines are clear, obvious and not the ones in question

"Each axle should have a vent line to the top of the axle housing.
There should be the control air line to the power divider on the intermediary axle differential(AWD to 6WD control when mode/6X is selected)"

Here's a picture of the intermediate axle:


The smaller air line toward the top of the picture, near the U-Joint, must be the control line that locks the axles together. The larger, toward the middle of the picture, on the square part of the axle is the one that goes to the rear and ends in a 45 elbox, shown here:



The air line coming down from the top of the picture to the T is the one that comes from the square portion of the intermediate axle, continuing down from the T it ends in the 45deg elbow shown at bottom center of the image.

That elbow has pipe dope on it, it was obviously connected to something at one point. If it's a vent, then aside from being a loose uncontrolled hose, it's probably not doing any harm.

If the brass "cap", vertical center right of the image, that rotates freely is a vent, then maybe removing the loose line, capping the lower side of the T and letting this line vent through the "cap" vent might be the play?

I am very curious to know where that 45 degree elbow was connected. There's no obvious empty or plugged place to thread that in.

I've not yet had the occasion to push the MODE button on the Allison shift panel, so I don't know what happens at that 45 elbow. I'll get the truck out of the garage, get someone to press the MODE button and see what happens back there.

 

[Ronmar]

Ok, the line from the middle of the top/square portion of the axle IS the axle vent line.

where is the axle vent line on the other axle? I could see the lines from the 2 separate axle vents being tied together into a common vent port(T fitting to vented cap)…

 

[dwlindsey]

Ok, the line from the middle of the top/square portion of the axle IS the axle vent line.

where is the axle vent line on the other axle? I could see the lines from the 2 separate axle vents being tied together into a common vent port(T fitting to vented cap)…

Ron:

That hint was VERY helpful. I hadn't thought to look on the rear axle. Sure enough, the air line reaches to a spot on the rear axle where there was a broken off portion of that 45 degree elbow. I hadn't recognized that as a broken fitting. If I ever looked at it, I may have thought it was a plug.

I wonder if that broke off before or after they had the truck over the axles in mud or sand? It was certainly before I pressure washed and painted the axle. So I've probably got an emulstion of oil, water, soap and sand in there. Sheesh!

I was heading toward changing the gear oil in that differential as part of the Eco Hub installation, but now I think I'll drain it, fill it, run it a bit and then drain and fill a second time. I'm hoping it's not completely full of sand . . .

I'm in awe of the support you and others provide here. Thanks so much!