Eaton 13 Speed getting stuck in neutral

alaskaforby4 · May 23, 2019

Hello, We have a 91 Pete that has a intermittent issue with shifting. Sometimes when splitting the gears on the high side it will go into some sort of neutral freewheel. The only way to get it to re-engage is to stop the truck using the brakes and re-start. This happens primarily on the splitter but has also done it a few times on the high/low selector as well. Looking for ideas?

Truck Shop · May 23, 2019

First Place to start is the air system and valves. The air is feed into the pressure regulator at right rear top of transmission, there are two range cyliners on the rear section.
The lower one on left is the splitter, the one on the top right behind the regulator is the range cylinder. The valve on the left side near the top/ middle is the slave valve.
Sounds like the air system is dry, remove the air fed line from frame to pressure regulator at rear of transmission, get a bottle of air tool oil and squirt a good amount down the
air fed line once it stops flowing air. Reconnect, build air and operate the low range and splitter back and forth several times. If it was dry it was also/probably shifting slow.
With the air tool oil it should speed up the shifts. Normally this symptom happens when the slave valve is dry. Moisture in those air lines is not good, water plays hell with
that air system. Has the air dryer been serviced recently?

RZucker · May 23, 2019

I don't like to just throw parts at stuff, but if it looks pretty old I will replace the filter/regulator unit if it looks like it has seen much moisture. So far I've been right on the last 3 cases. The air tool oil first.

alaskaforby4 · May 23, 2019

It has a very old looking self contained Bendix Air dryer. Maybe I should look into this, as we did have some issues this winter with ice in the lines not allowing the box to raise or lower. I'll squirt some oil in the lines and see about getting a new element or whatever air dryer takes. Thanks for ideas!!!

Nige · May 24, 2019

I may be well off-base here but I always thought that the idea was to keep water and oil out of the air system downstream of the air compressor but maybe I'm wrong............

Truck Shop · May 24, 2019

Nige said:
I may be well off-base here but I always thought that the idea was to keep water and oil out of the air system downstream of the air compressor but maybe I'm wrong............

Correct, but over time the air system on these transmissions will collect crap and the o-rings start to drag instead of sliding. Plus where I was headed with the air dryer without asking
the direct question told me a possibility of air line antifreeze could have been used to clear the ice in the air lines. I hate airline antifreeze {alcohol} it dries out any air valves it makes
it's way to.

alaskaforby4 · May 27, 2019

This is the dryer. Anyone familiar with servicing it or just by new?
Hoping to lube up and try the system tomorrow

funwithfuel · May 27, 2019

You remove the whole unit, split the nuts and bolts around the perimeter. Swap out the desiccant and put her back together. Now turn it upside down and take those 3 little screws out and replace the purge valve/heater assembly. Reinstall and your done. Or in the interest of time, swap with a reman unit.

Nige · May 27, 2019

I'd be interested to hear what's the recommended interval between dessicant cartridge replacements for an on-highway truck..?
Our off-highway equipment we replace every 1000 hours which equates to every couple of months give or take.

Nige · May 27, 2019

Truck Shop said:
Correct, but over time the air system on these transmissions will collect crap and the o-rings start to drag instead of sliding.

Interested to hear what the fix is. Strip & clean the valve, S&C plus some sort of lubricant, etc, etc..?

funwithfuel · May 27, 2019

On highway is recommended annually. Truck shop will back me on this, they're usually forgotten till something happens.

funwithfuel · May 27, 2019

The exhaust ports aren't substantial enough to purge the dirt and crud. You would have to disassemble clean/polish and reseal. It's a PITA but the only 'right' way to do the job. I myself have sprayed blaster or wd-40 in a slave or 20 over the years.
Plus, like truck shop mentioned, the air brake alcohol is terrible. It turns the aluminum to chalk, corrodes relay valves from the inside.
You wanna really lose hair quick. Try to troubleshoot an air problem on a gradall that someone pours alcohol into regularly. Holy smokes, I just wanna burn it to the ground and start over.

Truck Shop · May 27, 2019

Bendix o-ring lube in the cylinders and on the o-rings.

alaskaforby4 · May 28, 2019

Excellent thanks, I think I’ll opt for a new one. This one is pretty crusty trying to get off. Ive found some more info on the on my neutral problem. It seems the splitter sometimes does not dump into the low side. And stays high, so if I shift into the low side (1-4) where there is no split available it makes terrible noise and stays in a neutral. So which actuator is the splitter and which line should I squirt some lube?

Truck Shop · May 28, 2019

In the bottom photo the feed line with the white fuller parts tag sticking up is the one to put air oil in. But before you do that-in the second photo remove the rubber hose to the
splitter valve and see if anything drains out of it. That line has a dip in it which is a collection point for oil and water.
There are only three ranges, low, direct and over drive. The Splitter will only work in direct and overdrive. Photo of the control knob please!

alaskaforby4 · May 28, 2019

Excellent, I will take care of this today. definitly going to check that rubber hose with the dip in it. It sounds like the splitter is unable to dump properly. The range selector from high to low has a very audible clunk when toggling up and down. The splitter on side, not so much. I am not by the truck but this is the type of shifter it has

Truck Shop · May 28, 2019

In that splitter valve is a shuttle valve that can get covered with crud. It is opposite the 5/32 line and has a port in the end of it, it takes a 7/8 socket to remove the cover plug and carefully use needle nose pliers to grab the stem without bending it pull it straight out and clean the bore it slides in and clean plus lube the shuttle and reinstall.

DMiller · May 28, 2019

Had occasion to just replace the shuttle on the Dir/OD spool, the pin insert was the culprit with debris damage over time that would not seal for shifts.

Truck Shop · May 28, 2019

I have two new ones in my tool box. And I agree Dave those shuttles can be problematic I'm just trying to help him through it without throwing any parts at it.
At least until they have an idea whats wrong.

mitch504 · May 29, 2019

This may have been mentioned but I didn't see it. Have you washed out the sintered brass filter under the 1 1/2" plug on the trans. air regulator yet?

Eaton 13 Speed getting stuck in neutral

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