Good morning, My name is XXXXX XXXXX I may be able to help you out. I need to ask a few questions to get started. Is the serial number prefix for this machine 8PJ? and if it isn't can you give me the serial number. and is there a hydraulic temperature guage on the machine or just a warning light? Do the hydraulics work well or are they weak?
Customer
serial-9gj00474...no hydraulic gauge or light....hydraulics very weak to stopping
hydraulics not engaging...will not go forward/backwards
Ok, the hydraulic system is not what controls the tracks to move forward and backward, that is the powertrain, the hydraulic system only controls the dozer blade and ripper. Does the dozer blade work properly?
Customer
yes-dozer blade works properly....
Ok, we are talking about the powertrain transmission system, just to clarify, is it the guage and warning light with a gear and thermometer symbol? and does it heat up as you try to drive the machine?
Customer
warning lights do not work...engine coolant temperature guage very hot...transmission forward to reverse slows then stops...
Ok, it sounds like we need to do some tests to find out what is wrong with the transmission. My thoughts are that the torque converter is failing. can you give me an indication of your mechanical skill? We will need to remove the cab floor plate, remove and inspect the powertrain oil filter and possibly perform some pressure tests.
Customer
1 yr. ago all filters were changed. torque converter checked. my mechanical skills are not good but have a neighbor with some skill. Since filters have been changed, crawler used only 20 hrs. I am a rancher and it is used in summer and fall only.
Ok, let's try a few simple checks, First, remove the floor plate and operate the machine until it warms up and the problem occurs, watch the drive shaft turn, as long as the machine is moving the driveshaft should move, if the driveshaft turns when the machine is not moving then the transmission is slipping, hold your foot on the brake and check the driveshaft in all gears forward and reverse. it should not move with your foot on the brake, keep the engine at about half throttle during this test. If the driveshaft is spinning when it shouldn't be then the problem is in the transmission, if the drive shaft stops in all gears then the problem is in the torque converter. Next, purchase a new powertrain oil filter, Caterpillar Part#:(NNN) NNN-NNNN it does not need to be from Caterpillar that's just the only part number that I have now. any parts store should be able to cross the number. Remove the powertrain oil filter that is under the floor plate and install the new filter. Cut the old filter open and remove a section of the filter pleats and squeeze the oil out in a vise and inspect the filter, if it has aluminum filings in it then that is an indication that the torque converter has failed. I just happen to be doing this exact test on a D8N this morning. I hope this helps, please let me know if you need anymore information. Thanks, XXXXX XXXXX
Customer
we need to go and work some cows as the vet just arrived to pregnancy test. we will have to put this off til we finish there. we will try this afternoon and then get back with you.
Customer
I'm communicating with my husband on this problem and giving you the info...he just clarified that it is the transmission that is overheating-not the hydraulics....the coolant gauge shows overheating....water boils out of coolant cap when opened and running....crawler will not go forward or backwards
Ok. It sounds like we may be talking about two different problems, a transmission that is in good condition should work no matter how hot it gets, within reason, the transmission will also not cause the engine to overheat. the reason that a transmission overheats is that it can't pass enough oil across the oil cooler to cool the oil properly. Perform the tests that I suggested on the transmission and then with the radiator cap removed fill the coolant to the top of the radiator and rev the engine up and down several times and see if the coolant level drops when the engine speed is increased. this will tell us if the water pump is working or not, let me know what you find and we make a decision on what to do from there.
Customer
Thank you...just finished with the vet and will try and do these suggestions after a bite to eat. Will let you know what happens.
Ok, I'll be around the rest of the day and tonight, and then I will be in and out on Thursday and Friday and may take a little while to get back to you.
Customer
ok...here is what was tried and the results...First-the crawler was operated for 1hr.45 minutes and worked fine then it would not change from forward to reverse until my husband worked the shift lever 3X then it would change. After 2 hours, he could not get it from forward to reverse.
Test performed as you advised:"First, remove the floor plate and operate the machine until it warms up and the problem occurs, watch the drive shaft turn, as long as the machine is moving the driveshaft should move, if the driveshaft turns when the machine is not moving then the transmission is slipping, hold your foot on the brake and check the driveshaft in all gears forward and reverse. it should not move with your foot on the brake, keep the engine at about half throttle during this test. If the driveshaft is spinning when it shouldn't be then the problem is in the transmission"...
Result:drive shaft did not move in forward; drive shaft in reverse moved in all 3 speeds; driveshaft always moved in neutral
Question...what are our options?
Ok, the fact that the drive line was still spinning in reverse indicates that the reverse clutch pack is slipping, the fact that the drive shaft is not spinning in forward, but the machine will still not move indicates that the torque converter is failing. the fact that the engine is overheating indicates a completely different problem altogether. I need to ask a couple of more questions, do the brakes feel like they are dragging, will the machine roll in neutral or does it stop as soon as you let off of the throttle? and did this problem come on quickly or has it been getting gradually worse?
Customer
Drive line was spinning because reverse would not engage. I assume forward would be the same if I had stopped in reverse. Machine would move forward but I was stepping on the brake and going thru the 3 speeds. Brakes don't drag. Machine rolls in neutral. Problem getting worse over time.
OK, just so that we are on the same page, with the all of the reverse gears selected and the brake pedal pushed the driveline still turned, I understand that you had it selected but it would not engage, but it should have. In all of the forward gears with the brake applied the driveline did not turn. that is what it is supposed to do. with the drive shaft in neutral the drive line turned, that is normal. I am concerned that the torque converter is failing and contaminating the transmission oil system and causing the valves in the transmission to not allow the gears to engage properly. Have you had a chance to cut the transmission oil filter open yet?
Customer
need to head to town to take someone to the airport and go to some appointments. Will get back to you later...have not opened the transmission oil filter yet.
Ok, cut it open and let me know what you find and we will decide what to do from there.
Just to let you know, I am going to be working on a jobsite today where I won't have cell service for my internet, so I won't be able to respond to you until about 8:00 PM Mountain time. Steve
Customer
Hi Steve,
I just returned from town with new transmission oil filter and the guys have just left to drive to where the crawler is and replace the filter. Hopefully this will correct the problem. I will let you know what they find out...they will be gone for several hours as the crawler is up on our forest permit where my husband was repairing a ditch.
Hello, I'm working out of town for a few days, so it may take a little to get back to you, but please let me know how things go and I will help you all that I can. Steve.
Customer
Thank you...I will be sure to let you know!
Customer
We cut the filter open, pulled it apart and did not see any aluminum filings. My husband operated the crawler for about 1.5 h and it did the same thing again....worked fine then it would not change from forward to reverse
Well that's a good thing, those little metal filings cost a lot of money. Well it looks like we are going to need to do some pressure tests in order to do much more troubleshooting, you indicated that you have a neighbor that may be able to help you test the pressures, you will need a couple of 500 PSI pressure guages and a 150 PSI pressure guage and some about 4' hoses and some o-ring boss couplings or some Caterpillar test port fittings to complete the tests. you will need to hook these guages up and test the machine when it is cold and then test it when the problem occurs and then record the readings. I can give you the test procedure, and the part numbers of of the fittings that you need if you decide to do the tests yourself. I don't know where you live and and I don't know the skills of you friend, but I am starting to think that you may want to consider having someone that already has the tools and has worked on these before to come and test it out. I don't want to discourage you from trying this yourself, but depending on what we find, you are not likely going to have the equipment to make the necessary repairs anyway. I don't recommend having the Caterpillar Dealer come out unless that's your only option. Let me know what you want to do and I will be glad to help in any way that I can. Steve
Customer
Thank you, Steve. Right now my husband wants to finish 1 more ditch repair and then start walking the crawler home....this may take 2 days. He then will decide about doing more tests and think about who might be able to help him or if there is anyone beside the CAT dealer to call.
What state are you in? I know several people in the western states, there may be someone that I could recommend. Steve
Customer
Colorado-Wyoming...ranch is in both states 50 miles nw of Steamboat Springs and 30 miles east of Baggs, WY....nearest towns are Craig, 70 miles away and Steamboat is 50 miles...Rawlins, WY is 110 miles (winter) and 60 miles summer and fall
I know that area fairly well, I'm in Utah and I spend quite a bit of time in Vernal and Rock Springs. Try this
link and see if it helps. Steve Phillips
Customer
Hi Steve,
The crawler is now here at the ranch and we have taken a break from the problems with it to deal with other obligations. I checked out the link and Terry may call you if this is ok.
Yes that's fine, even if you don't want to do anything about it now, we can discuss your options. Talk to you soon. Steve
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