Been running a d8t pushing in a pit, sometimes when i pushing up hill or or even backing uphill, it will act like the parking brake is slaming on,have to put in neutal and then forward reverse and then it gos in whatever direction im needing, 6,500 hrs on it getting worse company just says keep running it,i like to know whats going on with it, but im old school this new dozers got to many switches and pumps on them, if was a old K or H ID have it figured out by know, but that being said this 8t is one fine dozer to run all day...any body got any ideas, all fluids check full the trany is overfull but i think some company guy might have overfilled it, i just got back on it after a month or so dont know whats been messed with.
saddleup, when this happens will it steer without moving or is it just totally locked up? it sounds like it is loosing brake pressure. I don't know for sure but I am pretty sure these still have spring applied pressure release brakes...so if you loose pressure they lock up. would you possibly say it only locks up one side? does it seem to drag first? if so that would indicate loss of seal on that sides brake piston.....post the serial number I will look into the brake system closer in sis........TIO
Thanks for helpin, it just totaly locks up,its worse say when im backing up to start anouther push and i have a breakover to where my push leavels out, i decelerat the power down at that point and it just slams into this lockup deal,i will get the serial number today, thanks..Matt
Well only got about three hours out of it this AM, started locking up so bad i was lucky to get it up out of the pit, it for sure locking up both tracks, it would only go about ten feet then lock up insted of fooling with gear and direction changes, i figured out just let it idle down then it would release and go anouther ten feet or so, didnt get a chance to get the serial numbers, jump on the old 77v and keep on moveing overburden...
If it locks up durring deceleration the trans /brake pump is supplying less flow at that Time indicating a leak in the system or worn Pump. Yes theses are spring applied brakes And oil released. The first check should be To inspect filter and screens for debris from A component failure.
Without knowing the Serial Number I just took a look at a random D8T schematic and the first thing that jumped out and hit me in the transmission ECM was an "Operator Presence Detection" input. In other words there's a sensor in the seat that tells the machine when an operator's sitting in it. I know when I run a tractor in reverse I have a tendency to lift my ass off the seat a tad, could that be what's happening here - either that or a maladjusted seat suspension mechanism..?
Great thought there Nige! I was thinking of the secondary brake pedal switch itself and or part of the secondary brake system, if the micro switch on the pedal has come loose and is actually being actuated? If the wiring harness itself had a poor connection on the park brake switch itself would cause this problem or the switch was failing however that part would be extremely unlikely because it has a built in redundancy. Follows is a paragraph from the service brake operation...TIO Service Brake Pedal Switch The service brake pedal switch operates independently of the ECM. The switch is a backup to the ECM and the brake pedal position sensor. Normally, the ECM applies the left and right brakes according to the position of the brake pedal position sensor. The switch ensures that the brakes are engaged if either the brake pedal position sensor or the ECM are not functioning properly. When the operator pushes the service brake pedal to near full travel, the switch closes and a +battery signal activates the secondary brake solenoid. The secondary brake solenoid engages the left and right brakes. The fuse for the dump valve is the source of the +battery signal. This ensures that the brakes can be applied even if the ECM would lose power. The service brake pedal switch is a single pole double throw. Only the Normally Open contact is used. The switch has two conditions. The two conditions are OFF or ON. The Normally Open contact of the switch is open when the brake pedal is not pushed. The switch closes when the operator pushes the brake pedal to the full travel position. The Normally Open contact of the switch connects to the secondary brake solenoid and connector contact J2-5 of the ECM. The pole connects at the fuse. The connection is for the dump valve. Note: The secondary brake solenoid is also connected to the ECM. The ECM will send +battery voltage to the secondary brake solenoid if the ECM detects the following conditions: The solenoid signal is not at +battery voltage. The brake pedal position sensor is at full travel. Note: The brake pedal position sensor is used to diagnose an INCORRECT condition of the service brake pedal switch. The ECM periodically checks the position of the sensor and the output of the secondary brake solenoid. The sensor tells the ECM when the brake pedal is at full travel. If the ECM does not detect +battery voltage at the output for the secondary brake solenoid and the brake pedal is at full travel, a diagnostic code for the service brake pedal switch is logged.
I do want to clear something up here my idea about loss of oil pressure through the brake pistons is wrong! It would be virtually impossible for this to create an intermittent full on condition. The failure is surely on the electrical side of the park brake or secondary brake system. This would include a loss of power going to the park brake solenoid, a solenoid failure or its oring, or intermittent power going to the secondary solenoid or its o-ring. Remove and ispect park brake switch and harness, remove and inspect secondary switch at brake pedal, remove seat (I think) to get to park brake and secondary brake solenoids inspect harness and solenoids, remove solenoids and inspect O-rings. Questions 1 does a light come on in the dash when the park brake is on? if so does this accur when problem accurs? if not I would look most closely look at the secondary brake system! Question 2 NIGE I randomly used KPZ 1000 serial number and I didn't locate the seat switch am I missing it or is it not in this serial number group? Good luck,......TIO
I used MLN-prefix. The Operator Presence Detection input is Pin 53 on connector J1 of the Powertrain ECM. You can find it at grid reference G-16 on page 4 of 331-4066 electrical schematic. The switch is shown at grid B-14 of the same page.
No park break light when it locks up, just light when you lift the button, the seat deal is a good idea had that problem with some other peice of equipment,cant think what it was, but know what you talking about, this has been going on intermitently for a month with differnt guys running it, guess they got a mechanic coming tomarrow, but have heard talk that its got to be the tranny, dont think so ,have to watch a see how much money gets spent on parts changeing before they listen and check this seat switch, Keep you posted on this deal if i can Thanks Matt
I suggest to make sure that if the "mechanic" who comes to troubleshoot it doesn't have a laptop with Cat ET to check for Diagnostic Codes that they boot his *** right back out of the gate. First thing they chould be looking for is the simple stuff, in this case the external electronics, before condemning the transmission.
Nige, for sure, im going to try like hell to be around when he shows, i seem to be the only one on the job paying attentoin to this deal, i would like to see it fixed right the first time and get back to work on it, the first 6 hours runnin the old really wore out open cab 8k was good yesterday , today not so much, im 61 YEARS OLD been runnin dozers since i was 12 or 14, ran about every model of Cat dozer starting on a 2u,point being i Really like these new ones, spent most of the season on a brand new put the first 1,000 hr on it 6T, FINEST MACHINE i ever ran.....
Shouldn't be a big deal, hook the pc up, start a log and run for a while until the fault occurs, check log, repair accordingly. Done it many times.
That's OK for us to say Per, but we're assuming that the "mechanic" who turns up to troubleshoot it has a laptop equipped with ET + a Comms Adapter.
Exactly what I thought there NIGE, wish I could get cat ET back again, but pretty much impossible for me, they consider me competition and I haven't figured an honest way around the dealer so I have to figure out things the old fashioned way usually I can get it done 80% of the time without the computer and usually before the cat guy can make it to the job, whatever keeps the customer happy......TIO
I'm not a mechanic, but in my experience with a D-8T, I would check the electronics first. It would be really odd to have a mechanical problem at 6500 hrs. The seat switch may be it, but I would look at the sending unit connected to the brake pedal on the floor. If it goes bad, the vibration may signal that the master brake pedal has been pushed when in reality it has not moved. This problem MAY not log a fault code, as it will read in the computer as a normal brake application. I love the machine, but HATE all the electronics.
No mechanic yesterday maybe one get here today, was a rainout yesterday, dont know why that would make a mecchanic not show up , but this is one of the busyist places in the country, waiting to get sombody to do any thing here is the norm.. where just out of Willeston , ND The way it acts think you guys are on the right track with it being a switch somewhere, again thanks for the help,i keep ypu posted..Matt
Don't all CAT dealer mechs have a laptop with ET on it? How are they supposed to do anything worthwhile on modern equipment then? The ability to use ET is in my opinion what separates us from any hillbilly with a worn out wrench in the backpocket......
Absolutely correct. I may be wrong but I get the idea from the OP that the mechanic who's coming to look at the machine isn't necessarily from the Cat dealer.
Still, no mechanic today, so pretty sure its a Cat dealer when he shows
I must say I've seen a lot more achieved by hillbillies with worn out wrenches than any Cat dealer mechanics with their ET laptop.
Well Guys,thanks for your help on the issues with the 8t, got to the job yesterday am, and the dozer had been loaded and hauled off somewhere, nobody had a time frame if or when it was coming back was told we just finesh job with the old 8k witch would be fine with me but i been trying to get enough oil and hygrolic fluid to keep it running, its a real leaker, no real boss around at the end of this job to say go to town and get what you need, so i said just said goodbye, fired up my moterhome and headed out of North Dakota a hour later ,time for us to go south for the winter anyway, so when i do hear what the deal was on it i will let you know, thanks again. Matt headed for Arizona
Per. That's is exactly the attitude that keeps us as far away from our local cat dealer as possible. You sir are arrogant!!! We are not friends!!
And I thought hillbillys were only in the US now I find out I got cousins in Sweden. But this hillbilly does have et and sis I guess that makes me a redneck hillbilly
High-tech redneck
:usa
Per, yes this is ONE thing that separates the Cat dealer mechs from the hillbillies, Cat has done a very good job keeping us hillbillies from getting ET this is what we call in the US as a monopoly don't know how they get away with it? Now if you think somehow your above the rest of us non OE mechanics in this world because you have a tool in your box we don't then you are sadly mistaken, you need to humble yourself a bit you are being judged, a tool is only as good as the person turning it, in fact being able to do a job without the designated tool is a sign of even greater ability! You obviously know how to use your ET but be assured that not all your fellow CAT dealer mechanics do!!! now for saddleup, how dare you get us involved in this discussion and then let us down right at the climax! lol. I love this, a machine that just got lowboyed to the shop because obviously no mobile mechanic was available!! my rate just went up again!! This entire story needs connected to the thread "the way we work?" this is a perfect example of how the customer pays for these service trucks which appear to get larger every year! The example here is a truck and trailer that can haul 45 tons costs 1.5 times what a fully loaded 33,000gvw service truck costs which means you can make 3 trips to the job site with the service truck to do the repair for the same money as lowboying to the shop and back, just wanted to show the numbers involved.......TIO
Way to go T.I.O.---- hey that rhymes I'm a poet and didn't know it:tong
T.I.O AND OUTHER GUYS ,i feel bad i didn't get this deal fallowed thru, but i will eventualy hear what it took to fix this 8. As for loading a machine becouse you cant, get a mechanic out pretty standerd deal up here, hell couple years ago had a cat grader with issues, wait time from dealer in Dickenson ,ND was three weeks the one in williston a month, we pushed the blade on a lowboy sent it to Gillette WY, Had it back in a week fixed.
Hey Saddleup, I know what you are talking about. If a person hasn't worked in the Bakken then it is hard to understand just how busy it really is there. Pretty much have to be prepared to do everything yourself.
Oxbow, thats right unless u see it hard to beleave was in a south Texas oil boom a few years ago,they where better set up to handle the people and buisness , dont matter what you want done better be ready to hear it be a month or more, Docters dentists car dealers warrenty work it a month or more for you get in then no telling how long it set before they work on it, hell it takes two and half hour wait at penzoil quiky lube in Williston. Was in New Town a few weeks ago at the big cenex truck stop at 5 am, they had 7 cashers going and 7 lines the shortest one i counted 32 guys in it, No i didn,t need what i wanted bad enough to wait..lol
oxbow, what is the Bakken? sounds like there is work there? is much of it federal or municipal? it would be tough to move a construction company there for private work! I am not looking but know someone who is, they like to handle 6-12mil gross a year they just got done with 2 years in Alaska and are looking for the next project with great mark-up. you can direct me or pm me whatever makes sense......TIO
T.I.O, The Bakken is a big oil and gas boom, in ND,keeps getting bigger every year, lots of constuction, roads, building trades,lots of work most all the oil drilling is on privet land , witch is why its booming no feds interfering to bad yet, they on there way though...just google oil boom
TIO, the Bakken is the name of the oil field that is present in Western North Dakota and Eastern Montana. There is a tremendous amount of work there, but with that comes logistical difficulties that are hard to imagine if you have not been there. Housing for employees is on the top of the list. Many of the Townships have put moritoiums on man camps, and are trying to control development growth to a pace that they can keep up with infrastructure wise. I believe things are starting to level out a bit now versus 2 or 3 years ago, but the demand for everything from housing to heavy equipment mechanics is tremendous. I worked there 2 winters ago hauling crude for some folks that I knew here in Idaho. They managed to find us a place to sleep and shower, and we had it better than most. I have never been so tired of convenient store pizzas! I went back and built some shop pads for the same folks last spring. It was cheaper for them to have me haul equipment from Idaho to do the job than to find someone there. To summarize, there are tremendous opportunities, but be prepared for winter conditions as tough as anywhere, spring breakup that litteraly breaks up most all of the roads until the frost is long gone, and some unscrupulous people. I had no bad experiences with anyone, but heard that it was hard to collect money from some. The crime rate for what was a quiet rural setting some years ago has increased dramatically as well.
thanks oxbow I knew of that boom, however you filled in some of the gaps a bit. didn't understand that was called "the bakken" anyhow definitely not the kind of circumstances this outfit likes, they don't even subcontract to anyone and rarely anything private.........TIO