No low range

We are a new farming couple in northern NY. We bought an older 1995 International Navistar 2674 L10 and 9 speed. It's an old village dump truck that was used as a plow truck. We are building a house and other buildings so we were (are) saving money by hauling stone and gravel ourselves for the foundations and our 1/4 mile driveway. After a new set of batteries, range slave valve and a few air leak repairs we had a very reasonably priced dump truck for our farm.

Well, the other morning my wife (I'm certainly not blaming her) started the truck to build air while I retrieved the backhoe. I heard the truck start fine with no noticeable alerts. I returned to hear an awful grinding over the exhaust of the backhoe! I quickly shut off the truck. I soon realized that my wife had thought she was putting the truck into neutral when she inadvertently engaged low gear. Air pressure released over a couple days from the range cylinder apparently allowed the range to go to a neutral position (truck didn't move when started in gear) and as air pressure built up, it tried to engage low range harder and harder until making an awful noise and I shut off the truck. I returned the transmission to neutral, started the truck and shifted range low to high and back. Everything sounded normal.

Making sure the range selector was in low, I put the transmission into low. It was an odd experience for me as the gear came with very little resistance (the clutch brake is non-existent). I released the clutch and the truck would not move. I return to neutral to range up to high and tried to go back into low. The familiar grinding returned until the transmission went into gear. Releasing the clutch, the truck started to move. Back into neutral and low range we go. The transmission easily goes into low gear...too easily. The truck does not move when releasing the clutch.

Remember, the range slave valve is new and air lines have been repaired so there are no leaks. The truck shifted OK previous to this morning...except for the clutch brake issue.

I have removed, cleaned, lubricated and assembled the air regulator filer, (1) O-ring, air regulator (and checked for proper regulated pressure [it's right at 60 psi]), range piston, (3) O-rings and cylinder. I have troubleshot the low/high shifter air. It does not leak and puffs off at the appropriate time. Removed low range supply line and it does have 60 psi only when low range is selected. Also, I removed high range supply line and it does not blow air when low range is selected. I thought if both high and low had pressure the range piston might go to neutral position?

I try to get the proper repair manual from Eaton, but I do not know the model number as the identification plate has rusted off or has been removed. I understand the model naming nomenclature but am unfamiliar with it's terms. I don't believe it's an overdrive transmission, there is no splitter, I don't know the ratios, the torque rating must be at least 950 ft. lb. so all I can assume is it's something like FR - 10n09xx. But assuming always gets me into trouble....like assuming everything will be good if my wife starts the truck! I'm not putting blame on her though....really.

Can anyone help me determine why I cannot get low range and allow me to repair our truck's transmission?

 

I removed the range cylinder cover today to watch what happens when the low range was selected. The piston only comes half-way out. As I suspected, there is air to the back side of the piston to push the piston out. There is no air leaking past the O-ring in the piston. Still, there must be something out of alignment. Maybe the yoke came out of its groove and only engages high range?

Thunder and rain started while I was under the truck. Not a great place to be...under a huge lightning rod in a field. I'll remove the range cylinder later to see if I can reach in to see if the yoke is in it's proper place in the synchronizer.

 

Yes, I just took another look after the storm passed. I could not get the yoke to come out of the synchronizer (Makes sense). I removed the driveshaft to be able to turn the output shaft. So far, no luck moving the range by hand. I must be able to turn the input shaft to mesh the high range to get room to have a look/feel as to what's happening with the low range issue.

I do not have a good set of pictures to know how it all works together to understand how it's suppose to work.

I'm not opposed to removing the auxiliary section, I just want to be sure the solution is in the removal since we do not have a nice concrete floor to work on and the proper devices to remove/install the section.

 

I started to remove things to get ready to remove the auxiliary section. Drive shaft is removed. I have a universal joint to replace while it's off. I started to clean out the three threaded holes and clean off the alignment pins. The truck was used as a salt truck and is very rusty. I spent 10 minutes cleaning out the drain plug trying to be sure I didn't unnecessarily disturb non-square hole because I needed all the material (even rust) to help bind on the wrench to remove it to drain the oil.

And here is my query. I drained only a quart from the transmission. I cannot see how that would be a good thing. Might that be my only issue? I now feel I am a bad truck owner. Did I check 1) Engine oil...Yes. 2)Power steering...Yes. 3)Coolant...Yes. 4)Hydraulic...Yes. 5)Transmission...No. 6)Differential...No. 7)Washer fluid...Yes (But the lines are not whole or attached).

The underside of the driveline is so rusty I didn't think any of the plugs would come out in one piece since I had to hunt to find them through the think and flaking rust. Apparently, the village I bought the truck from thought the same thing because they owned it since it was new in 1994. I have had it a couple of months and driven maybe 40 miles. There was some wetness around the PTO and the output yoke, but I didn't think it would have been THAT bad.

Since there was little lubrication, I questioned if it was really desirable to remove the auxiliary section. I inserted a mirror into the auxiliary section though the slave piston hole. I looked for broken/bent pins, broken teeth and signs of anything lying about that would signify that something wasn't working. Everything looked surprisingly clean and even wearing. Maybe I could reassemble everything add the proper amount of oil and give it a go!

 

If you don't have time to waste, go to the last sentence of this post for the short version.

I had my glass half full and put some oil in the transmission to test it. The few minutes to put it back together and fill it with oil I thought would be well worth the time and effort. If it was just a lubrication issue as to why I could only select high range I was willing to take the risk. I did not (and will not) put the recommended oil in the transmission. This truck will not see another 5,000 miles in my ownership and my lifetime. This year, it will haul 200 or so ton stone and gravel home from a quarry 5 miles away or move dirt and rock about my property here while I build my house and pond. After that, it will most likely be retired to plow my 3/4 mile driveway and private roads of snow during the winter. I will not spend $200 for synthetic oil for the truck. Conventional oil did truckers well for a century, it will do well for me an my truck for my requests and it's intended purpose.

I have to say that there was little gear grinding upon initial entry into gear even though the clutch brake does not operate as it should. The proper amount of lubricating oil surely made a big difference. I didn't expect the range to go into low at first try until I was sure oil was everywhere in the transmission to coat everything that may have been a little worn or buggered up. I took it for a short drive to a turn around point about a mile and a half away. I backed onto a side road to make my return. I shifted into low range, moved the shifter from reverse to low gear and let out the clutch. To my surprise, the truck moved forward with ease! Not the labored chug of high range. In disbelief, I selected high range, shifted to neutral and back to low. I got the familiar chug. Now, I'm excited! Back to low range, push the shifter to neutral, pull back to low gear and let out the clutch.....nothing!

Disappointed, I shift back to high range low gear and head home. About a half mile along the journey home, I'm still hopeful. I pull half off the road as I come to a stop. Shifting to low range, low gear I have a glimmer of happiness as I felt the grinding of gears. I let out the clutch once again to have any chance of satisfaction diminished. I feel foolish for not taking AModelCat's advice to heart.

It is now time to go home, drain the oil and remove the auxiliary section as I should have before instead of believing my glass was half full. I shift back to low range and low gear, ready to make that long trek home to break out the jack and wrenches. I let out the clutch...nothing! OH NO! Frantic, I try every combination to get the truck to move. The more I try this combination or that combination, the more I realize the truck will have to be towed. Now I really feel like an idiot.

This story is getting too long. I'm realizing it is an effort to put off starting the repair process. I need to yank the band-aid off. Finish the post. Get busy. Sorry, I'm such a procrastinator this morning.

Shortening the story...I walked home and with a friend's help, we drove the backhoe to the truck hooked on a chain and towed it home. It now sits waiting for me to close the lid on the laptop and get off my ***.

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I put it back together, oil in it, drove it....still no reliable shifting into either selected range and I need to remove the auxiliary section for inspection and repair.