We lost something in the transmission of our D8H and she’s immobilized where she sits. Operator was in a straight line push and hear a loud pop under his seat and the machine came to a stop. He said it felt like it was still trying to push ahead but could not “catch”. So I guess it was more like a bump bump of the machine trying to pull ahead? Not sure. But he said no grinding noises were heard. It also was hung in gear. Could not get the shift lever to move. We took the linkages off and the F-R post would move but not the 1-2-3 gear selection post. Not sure what that tells us. We did disconnect the linkages to see if the posts would move by hand with no luck. All froze up on the gear selection post. I restarted the machine today and all I can tell is that the engine is definitely under load. With the linkages reconnected I moved them around a bit and did get the gear selection post to move. Wouldn’t take gear or anything but at least it moved. So progress?… I’ve bought a copy of a copy of a copy of the manual for the machine but haven’t yet come across where there’s a detail on how to move the machine when disabled. Would anyone be able to help me out on what to do to allow the machine to free wheel? Once we can drag back to the shop we plan to go further. SN:46A27403
The post you just quite see below the shaft is the 1-2-3 gear selector post that was/is frozen up
Is your driveshaft turning? Did you pull the screens and look for metal? There's three of them. Are the filters intact or collapsed? Do you have any oil pressure at the pump. If you have oil pressure and the filters and screens are clear, you should be able to disengage the steering clutches (pull both turning sticks) and push her with another 7 or 8. Wouldn't hurt to pull the driveline if you think the transmission is locked up so as to isolate the damage to the transmission and cross shaft.
I tried pulling both clutches and holding them with the engine running and the machine was able to freewheel. That got it up and out of the way. I did try letting off one of the clutches to see if it would lock back up and it did on both sides. I'm guessing this says something has gone bad in the transmission. Good news is I didn't hear any bad noises while moving it. No pops or grinding of any kind. The engine does still sound like its under a load at idle when its running. It would not speed up at a normal RPM increase rate like it would in neutral normally. Its raining again here, so more diagnostics will have to wait a day or two until we can get back to the machine. We'll pull the floor plates and take a look at what is still spinning and then check the filters as well.
I got some ideas, but best to wait and see what you find. Split planet carrier comes to mind. Seen it on a D7F.
I’m reading through the service manual and found the planet carrier shown in the torque divider. If the divider fails wouldn’t it be a safe bet that I would hear grinding or some other noises? I ask because right now there is no such noise coming out of the machine. We got heavy rain over night but should be dry from later today till next week so we should be able to pull screens filters and the top of the trans off so we can take a look inside
Transmission has them as well. If something breaks and locks something, maybe no noise? The D7F carrier was in the transmission.
You were describing a problem in your transmission. Your torque divider (I call it a torque converter) is separate from your transmission, although they share the same oil (and debris). When you get a look inside your screens and filters, you can begin to figure out what isn't the problem, as in it isn't a catastrophic failure. If there's normal debris in the screens and filters, your transmission case isn't likely to be full of 5 or 6 handfulls of gears and bearings measuring 2" to dust. There are two plantetaries in the transmission. If either one of those started to come apart, you'd see evidence of that in the filters and screens long before failure. I'm still puzzled re why the release of one stick would lock up both sides. You can check that again and check the brakes as well to see if they lock up the tracks when the clutches are disengaged. The issue in my mind is you are describing a main valve problem, in that your linkage won't move. If your valve isn't moving because it's full of debris, then maybe there's something similar going on in your priority valve and it's what's causing an odd condition with your steering clutches. Too soon for any light bulbs to go on in my brain. So, screens, filters, then pressures if the screens and filters are normal. After that, if she still checks out, dig into the valves. Others may have better advice.
This is what the manual describes for checking out the machine transmission in troubleshooting. I also found it interesting that it mentioned the oil pump. Another contractor who’s long since retired but once ran a good many of these old H’s and K’s said that he thought the pump could be suffering from cavitation or failed all together. Last summer the pump had been leaking and we fixed the leaks but maybe that was a sign of failure starting up? Also one of the current operators has previously told me they’d heard a thumping noise coming from the transmission before but then found that they’d neglected to check the oil and it was low. (That was a whole different story) Topped it off and the noise stopped. Maybe it was damaged then. We’ll get the screens and filters off to see what’s there and go on from what we see at that time. I’ve got a bad feeling that the transmission is coming out.
The mention of debris if a carrier let go. Sure if it was a slow deal, if it was sudden like the loud pop the operator heard. That is a sudden destruction deal and likely would not pre pollute the oil, sudden break is usually a metal fatigue break, and starts with a small stress riser not something wearing out. Then the mention of the trans pump, I thought the op said it was run and the steer clutches released, the pump is working then. Then it was mentioned that in gear the engine acts like it is loaded. I'm guessing the torque converter is loading it because the transmission is locked up. And again a sign the pump is working. The pump is not an issue in this. And did you ever get the floor plates off, and check the U joints for turning or not? If they don't turn under engine power and in neutral, with engine off use a small pry bar, or screw driver stuck in it and try to turn it, right or left.
Wanted to follow up, we lost our D155 to a wiring issue and have been chasing that down. Will get into this dozer again once the other is back up
Checked filters today here what we saw:
THAT doesn't look promising....
More importantly, what do the screen have in it? Bad Bob
x2. What's in the screens. Those filters have been in there a long time. That shiny flake is aluminum and maybe there's a piece of a plastic thrust washer in your first picture. Those filters are beat but they look like they're intact and still working. There's three magnetic screens on that tractor. Pull them out and post some pictures. So far you haven't found the failure.
Main aluminum item is the stator. Don't remember if there are Al bearings in the transmission. So did the drive shaft turn okay?
Well I’ve had our mechanic tied up and pushed this off to the back burner. We’ve called in TEC to help get us caught up we were having so many back to back failures. Maybe this will be the week we can get back into the trouble of this dozer
So that’s what we got in the magnet… No good… Thoughts?
Definitely trying to eat itself. You just have to narrow it down between the torque divider and the trans, but with that much crap, it may be all through both. When you pull the drain plugs, which compartment has the most crap?
I think you have a catastrophic failure. From what I see, all your pictures are of the same screen. There's two more, one under the seat and another up by the cooler. You need to pull those as well. IMO, everything will have to come out all the way forward to the cooler. The bevel gear case will take you a while to clean measured by the day. Some guys will tell you that's what filters are for, but you're just risking another failure if you don't get it clean. Probably end up working on the cross shaft through the pinions while you're in there. All hoses not replaced will have to be steamed out. I hope you have a shop manual. It will make your job a lot easier.
If i was your mech i would say catastrophic failure in trans... and all associates... That thing has to be overhauled, from converter to sprockets ... miracle is if u´re lucky enough your convertor and oil pump will survive, but from what we could see from the pressure filters, alu particles... that might be understood as convertor particules and main oil pump chambers will be damaged too. In my world that is a F(/%$% expesive repair... Anyway i wich u could salvage the convertor and the pump, and with luck most or your trans parts, as that much damage points to pinion bevel gear failure.... if that the case u might get along no so bad. i´m so sorry to see it. good luck
Might be better off finding a good 8K that needs an engine.........
We have also confirmed that the drive shaft is not turning. I have a video but am looking into how to convert for upload.
I’d be pulling the torque and tranny out anyway looking at that.Everything needs to see daylight now.
We'll get those pulled as well and photos up. I should have the video up soon too. With the engine running the drive shaft is not spinning and when you move the transmission selector to any other position beyond neutral nothing changes. Engine continues to sound like its in a bind/under a load.
Post it to YouTube and link it.
I was trying to use Reddit like a fool. Forgot YouTube is owned by Google.... D8H Drive Shaft Video:
My thought is remove the transmission and pull it apart.
How did you run it? Clean all the mess and reinstall it? At this point and after seeing the mess I would not have started it. A simple longish screw driver or pry bar to try to turn the U joints. Running it just helps pump more dirty fluids. Like others mentioned, that oil is shared from torque converter, transmission, bevel gears, steering clutches, and can if the seals are bad get into the finals. Seeing ferrous in the magnets not good. I would bet even parts for those are crazy high now, not like 30 years ago. Lots of cost to keep an antique on the job.
Transmission grenaded
My thoughts are 30-50 grand hope its less but doubt it
Transmission & converter out and completely stripped to get the debris out. (You'll need a shovel) All powertrain oil lines off and sponge gunned. That metallic debris will be everywhere. New transmission pump, new cooler. And that's probably not the full list of what needs doing........ As Jonas said, if you get away with $50k or less count yourself lucky.
No good answer for the stupid move. Ignorance on my part. Mainly I’d say I just didn’t connect the dots. Our mechanic is not terribly versed in most of the work on these machines and is a non-English speaking/reading. So manuals don’t help him much unless I’m there to help. I speak enough Spanish to hold a basic conversation but lack the nuance to get into details. Our experienced mechanic had a stoke at an early age last July and had to leave to go home unfortunately. Admittedly, I have been learning a few things with these older machines and generally other mechanic related type things the hard way since our experienced mechanic had his health fail him. I really leaned on him to help me not “F” up on stuff like this. Hind sight being what it is, I should have known better. Not a terribly complicated concept to understand.
Reading through these comments it would seem: 1. The machine is done. Cost of repair vs real value of machine is upside down. 2. I need to open my eyes stop and think a little more when something like this happens. 3. This machine might be an organ donor for another dozer like a D8K I guess next pictures I get up will be of the other screens and dragging her back home.
631G. If it still has value for parts scrap it. Start doing research with all our help to find a machine to replace it.
YIKES!!!! Going to have to rob a bank for that 1
Well , to me looks like u haven´t realize the extention of the damage u got there. But i´ve been there, and now is just time to inspect what u can salvage, and take decisions.... There in the States u can find either a XTM donner machine or a machine that need an engine, and still good on Iron´s and u may getting out of this spending few, this if u are willing to go through that assle. Good luck at it.
631G,don’t beat yourself up.These things do happen,and anyone saying they’ve not made mistakes is a liar. It’s also difficult to think straight when you’re under pressure like this wondering if you’ll have the money to put things right. My advice is this,if you’ve the work for a D8,buy another couple.The one that’s calved down will pay for itself constantly if you’ve a couple more D8’s in the stable. Buy 2 more D8H’s if possible as you’ve allready got an engine and 2 final drives,not to mention $1000’s worth of pumps,radiator,track frame parts etc. Look at this as a positive thing instead. I’ve had loads of D8’s over the years,and can tell you that running 2 D8’s is a headache,but running only one is a freaking nightmare that will put you in a straight jacket.
Great advice above. I think this is hands down better than getting newer high drive iron that is equally cobbled up and full of issues and having no spares to boot. They all suck that way.
Dozer = Money pit
If you have to pay some one to wrench on equipment, and use it for a thriving business, using antiques for machines doesn't make sense. Okay for the hobbyist here and there clearing or dirt guy that is a DIY mechanic sort, there is so much that can be junk in these old machines now, sorta like us older guys, its called metal fatigue, so what is it, the last of the D8H's are now what close to 50 years old, and the ones before minus another 15 or so. No one absolutely no one was in 1970 using any dirt moving machines from 1920, and is part of what I don't understand about some of the stupid crazy prices of old worn out equipment. I've seen so many different problems on the D8H's and K's. Massively cracked out main frames, front and rear, cracked flywheel housings, various engine problems like loose lifter blocks and such, they all have been hammered for years they are getting tired. Maybe consider a newer off cat brand. Its like do you do work with the machines or do you just like to work on the machines? That is how I see it when it comes to using 50 plus year old equipment for a business. One other thing, how many here use a 1960s to 70's pickup for business?
He he , that is very well said but , let me through my 5 bucks at it... How much is a new D8 this days , half milion, u got to have a very good business going to "amortize"(pay it over long term) , a machine like that, wich in the end is also subject to failures... But with a ten´t of a milion one can deep overhaul a D8H or K , and work for another 10 years,... ppl just don´t do it, cause this machines are so great that they last and last... the member above was just unlucky as he had a catastrophick failure on the transmission, wich is something u dont expect... as this XTM was built to colapse by oil press or friction disks, converter ... not a crown/pinion gear .... I do really understand this move, but one doing this got to be prepared with knowledge to fix this problems , either by himself or colaborators in the business... Same with parts , a CAT original that seels at 1K when purchased from ITW for instance is 200 , same iron ... its proved, and its not china made , or it is but at least say fake china ... regards to all
I looks like a catastrophic failure probably a planetary came apart not something you can predict or prevent
To be fair though, the technological improvements from 1920 to 1970 were vastly greater then the improvements from 1970 to 2023. Operator comfort and ease of serviceability has improved over the past fifty years, operator comfort especially, but they are still torque converter drive hydraulic machines today with diesel engines. Having no idea what condition the rest of the machine is in nor what it is being used for. I am not sure many of us can offer any advice. They made over 30 000 D8H's and goodness knows how many D8K's. There is probably a good supply of used parts out there and if it was a really good condition machine with near 100% undercarriage, a known component history and great frame, being used for intermittent work, but needed something that big to do the job, it would probably be worth fixing. How many millions is a new 300hp bulldozer worth? Certainly somewhere between 1 and 2.
Equipment, new OR old is a pay to play proposition, If you're going to do it very steady you need newer equipment...if you have newer equipment you need to do it steady...if you get my drift.
With a ready supply of second hand parts it should be a cheap enough fix . Standardizing the "fleet" with dozers of the same model bit late at this point unless the D8 has to be let go , getting another D155 a good option . Comments about getting later model tractors all very well if you customers can pay to support replacement upgrade , after all its the customers who pay for the machine .
Got the screens out from under the seat and here’s what we saw. Looks like more thrust washer and maybe a piece of a gear? I’ll get you all some over all photos of the machine so you can see what it looks like.
Clean the screens. Replace the filters. Remove the driveline between the converter and trans input shaft. Hopefully you still have some pump pressure. Disengage the clutches, push her onto the lowbed and take her home. We have one 46A. Built from two. Spent $100K on the rebuild and another $50K or so of our own labor. She returned that in under two years and a whole lot more. We're not pushing scrapers all day long or moving a million yards of dirt a year so the investment made sense. Rebuilt three 77V-s thereafter (torn down to every nut and bolt) and they all made substantially more than the $200K or so investment in each. Just depends on what you need a dozer for and how she pencils out. Your biggest expense is operator damage, not parts and labor. Now to determine the value of what you have left. If a 7500 hr motor and a 100% worn undercarriage, she's just a core and the finals are likely the same. Still, if Italian parts are still available ( https://www.ghinassi.com ), she might be worth saving if you find another machine full of useable CAT parts.
If you start the motor with the driveline removed the flange shaft will puke out if the torque divider and you will see if there are really 35 gallons of oil in there. Bad Bob
Wow ! In this and the coming soon economy that would make zero sense. 100k and 50k labor? Did you mean parts and labor? All that cash and in the end depending on s/n its still just an old D8. Like the OP's case metal fatigue could bite something at any time, could be a final, transmission, engine or what ever. If its being used to work hard it will happen at some time. I'd like to hear more details about the rebuilds and what was done and by who. And what sort of up dates were done? The question is how much longer will the old machines that don't have brand new electronic engines installed be allowed to work on jobs that pay. I think that is already a california thing isn't it?
Yeah the best options maybe one of 2, removing the transmission, or steering clutches. But with a locked up transmission, I guess the only option is removing the transmission. Could try applying some air to release the clutches? May need some oil added, to help seal the rings.
New D8's are past $1,000,000. Not everybody needs a D8 running 16 hours a day and can amortize that expense in a rational manner. A good rebuild thoroughly done by people who know what they are doing can provide many thousands of hours of good service. As in Cheak Break's case, it can be very financially logical in certain circumstances. The current and "coming soon" economy make financing a million dollars even less viable. Depending on the OP's business situation overhaul could be a viable option.
My mistake. Should have known better as we had a bad leak there once. Not 35 gallons but at least 15. I forgot that shaft would come out and ruin the converter. I'm running out of easy options. What's left. Unbolt the final drive pinions from the steering clutches. I always worry about making a bad situation worse. She'd be intact and the finals would be free, but given the short ride home, maybe unnecessary. No way to know for sure unless the problem gets worse.
1 million $, who's saying get a new one? For a fraction of the time to rebuild, and $, a very good low hour off brand can be found. Depending on how many people involved, the total rebuild could take up to a year. If it just one or 2 guys in the shop that have to fix everything else that gets broke, even longer. I'd like to know when that person had the rebuild done. Its likely close to 50K to have a D342 rebuilt now, then there is the everything else, back in the early 90's to have a cat dealer swap out a crankshaft and rebuild the torque converter in an old D9G, was if my memory is correct 30K, I think they swapped the crank, leaving everything on top and pistons-rods in, engine out of course. I'm thinking in the now inflated price time, that the fellows complete rebuild would be pushing 400K depending on who is doing it of course. Maybe John knows more about all this. So it looks like you have a D155, and that would be an excellent choice for another "off brand". And newer than a D8H. If I was needing a machine to work on a job for my business vs a complete rebuild of an old D8, this would be my choice.
. . . To each their own . . .
Hehe, guys ... I´f we were to rebuild a dozer like the D8 size certainly was not a H or a K... as there are the R´s in there multiple series , or even early L´s and in my opinion this ones are much more easy to work on as they are modular machines as the H´S and k´s are not. Also this later models can be reengined as they are much easy to access to. Regarding the others "off brand" a D155 is much more than a "off brand" machine ... only persons that do not had contact with a Komatsu can say that... the D155AX does not owe nothing to a D8L or R as they are for the same period. in my opinion the 155 is much more flexible tha the D8´s of the ERA.
I'd like to know when that person had the rebuild done. Its likely close to 50K to have a D342 rebuilt now, then there is the everything else, back in the early 90's to have a cat dealer swap out a crankshaft and rebuild the torque converter in an old D9G, was if my memory is correct 30K, I think they swapped the crank, leaving everything on top and pistons-rods in, engine out of course. I'm thinking in the now inflated price time, that the fellows complete rebuild would be pushing 400K depending on who is doing it of course. Thank you for your concern for my financial condition. Perhaps I didn't make it clear that these four machines were profitable making the rebuild cost reasonable. A new machine would have not done as well. This was done between 1992 and 2002, and yes, it takes two guys half a year to work one over completely. I wouldn't pay someone $50K for a rebuilt D342 today out of fear of them cutting corners. Twenty years ago a new crank was over $10,000, less if you knew a few tricks. No rebuilder is going to start with a new crank now. I once looked at a 46A that had $140K in CAT dealer repairs. I was thinking it would be as good as ours for less than half the cost but it was scrap and the owner broke. We all make decisions based upon our own situations. May yours work well for you.
I am a fan of Komatsu dozers, as well as the old D8's. Your are correct. I say off brand because many folks are Cat only.
Question on this old D8H and the D8K we have, how much of the parts from one to the other are compatible? The D8H in question is done for sure less we find a machine that needs an engine for the right price. But we do have a D8K that may could use parts from the D8H. I plan to try and spend some time going through SIS to see what parts numbers will pull up crossing over (just learned that trick recently) but thought that the group here might know right off.
Right now this is the plan. We rent some space in what really just amounts to a farmers field to keep room open at our shop and that's where she's going, the bone yard....
Yes we have a D155AX-5. We got it back up once we determined that the engine controller computer had died. Somehow it grounded out internally. It's a good machine, but even it is getting troublesome for parts availability and its only 22 years old. I really like the Komatsu equipment we have and the after the sale support we get from TEC our local dealer is top notch. Oddly, we can buy another 155 for a much more reasonable price that we could that of a similar D8R or D8T. It would seem from my searches on Machinery Trader that a D155-6 or -7 can be bought for about the same as a D8N with usually much less frame hours.
I'd go for the Komatsu.
There are about 7 D155's in my little country for sale at the moment -6's and 7's , dozers are very expensive here , I think any way . Trade Me www.trademe.co.nz
With those prices, the economy there must be booming, and tons of dozer work as well. Fuel there must be $2 a gallon.
We are doing alright , sales of pine logs to asia drive the machinery demand . Diesel about $ 1.80 per liter cheapest I can get it . It costs more to fill a D155 than put new batteries in one . Cost per ton of dirt moved is cheaper the bigger the dozer .
the conversion is 0.62 for the NZ dollar.
So that liter is $1.11?
yes and the 475K dozer is 295K
Those prices include 15 % GST , which is claimed back for a business operator or not charged at all on exported machinery .
Get onto the Facebook page "moving the earth with D8", ACME (Antique Caterpillar Machinery Enthusiast) Caterpillar Equipment old and new, theres dozens of groups there and several working Cats for sale. Cheap. Theres also Machinery Trader, Rock and Dirt, many others. They have a "parts" search function that you can filter by make or model etc. I dont think it's worth overthinking this, problem 1) your operator wasn't aware of the maintenance needed to keep that Dozer going daily and your mechanic was absent. Big issue there running any age equipment. 3rd strike: ran low on fluid till it was thumping, meaning gears and bearings got lack of lube, overheated and damaged and that's why you are here. Get another decent used machine that hasn't been run by an idiot and you'll get many more years of good use. And all for less than a trans rebuild. You want a one-owner or retiring owner operator if you can find one. Not a bad idea to upgrade to K model for sure but either way a late model H is a hell of a machine and there is GOBS of parts lying around the country. I dont know anyone short of Oil Company that can afford a newer Dozer NOR the constant emission / management system computer malfunctions.
I agree with you. This one is done. Too costly to get back square. I’ve been on Machinery Trader looking at D8K and H’s. They’re out there for sure and absolutely for a decent price. The operator issue is on going. Most just haven’t touched these older machines. Oddly enough the operator that was running it when the thumping occurred, when questioned, couldn’t even tell me where the dip stick was on the transmission and he’s been around these machines the most based on work history and age if that can be considered for what some one should or should be familiar with. I know now, or at least know more, about what to do with training and inspection for these machines as a result of this. Expensive lessons…