Hi all, I have found this site very informative so I will ask yet another question: I have a D6C Ser# 76A1197 and the transmission concerns me. When first working for the day it goes into gear fine and has lots of power and steers well but after some time, (anywhere from 2 hours to 8 hours) then it starts to act up. It will appear to go into gear and and then it loses power, not the engine, but feels like the transmission is not engaged and the dozer comes to a stop and makes a kind of whining noise. Sometimes it takes several attempts to get it back into gear, sometimes it takes one attempt, but once its in, its good, once again lots of power with no tourque loss that I can tell. The fluid level is normal when first started (engine running at low idle) but goes up above normal after a while. There appears to be no rhyme or reason to whrn it will act up. My questions are: 1. Sould I even be concerned about it as the dozer is old and it does work pretty good overall 2. What do you think is the problem? 3. Should I change the transmission oil? and if so... 4. How much oil does this particular model take? 5. What about the transmission oil screen how do I service that if that might be the problem if it even has one? (im new to all this) thanks in advance for yalls advice P.S. I have changed the transmission filter a few times and it appears to make a slight difference, not sure if its just my imagination.
One comment I can make is the longer you run it with out a fix the more the repair will cost you.Good luck.
There is a screen and magnetic under the floor board right side i believe behind brake pedals.Also there is a screen in the bottom of the torque converter.Plate you can take off of the belly pan to get to it. The top magnet cacths most of the iron if there is something going bad(transmisson).The bottom screen in the torque usual not bad.You should only get a gallon or two of oil out of the convertor.Won't drain the whole transmission. It could be your transmisson pump is getting bad or the convertor is filling up with oil.Scavenger pump getting bad in the torque convertor.Good luck:usa
I think your trans pump is shot. My D6D acted exactly like that, this fixed it completely. When I took the old pump apart, it smelled burned and the housing was scored badly around the gears.
if it was the scavange pump the oil level should go down not up.. quite possibly it's the trans pump.. but i would also change the scavange pump to be safe. happened to me where the trans pump needed replacing but then it would flood the torque because the old scavange pump couldnt keep up to the new trans pump
Had some slack in the linkage under the seat on a D8K that caused it to partially pressurize foreward and reverse clutches if the machine was at an angle. Felt like it was pulling hard with little load, other times it ran fine. Tightened the linkage, all was good. Checking detents and shift linkage is one thing to eleminate.
Interesting... now that brings me to the next important question. How hard is it to replace? Anybody got any tips?
the trans pump should be on the right side on the back of the engine. it's very easy to replace.
Thanks, this is great guys, now iv'e got some direction. How hard is it to replace the scavenge pump scince it should be done at the same time? Oh and ill check that linkage too.
Well I pulled the trans pump off and found some scoring inside the housing, so im hoping you all are right and this fixes the problem. Ordered the part today.
Most of the advice you are getting is good especially the part about checking screens. If you have metal in the screens don’t waste money on a new pump. Pumps don’t get scored without a cause and usually the source is debris in the system or oil starvation both of which will occur again with the new pump. Did you cut open your old filters? Also, after checking screens the next thing I like to do it pull the floor plate and see if the drive shaft is turning (when the problem occurs) and this will quickly tell you if the problem is in the torque or trans.
Have not done the screens yet but am planning on it. From what I can tell its pretty straight forward, open it up and wash the screen off and put it back right? And no I did not cut open the old filters, thats a good idea.
Cool, but if anything is on the screen don’t clean it! It's best to let someone (like us :thumbsup) have a look first to try and identify the source of the contamination. Otherwise you'll be back here at the forums with a premature pump failure in no time. We might be able to analyze it visually if you could send/post some clear pictures. If not, i would highly recommend shipping them to us. It would be very inexpensive and we could easily send a replacement set of screens to get the machine back in the dirt for you.
I have a D6C service manual if you need any particular info, like pressure checks. Another place you could post your question for more advice is the ACMOC forum, for older Cat equipment. I'm not familiar with the D6C internals, although I operated one for a year. The older D8H powershifts had 2 intake screens for the pumps located in the bottom front face of the transmission housing. I had a suction hose leak once that caused the trans to lose it's prime when warm, the D8 trans had a valve that would push the gearshift back into neutral should trans pressure get too low. There was more than one suction hose leading to the trans pump, so that caused me some grief at the time. Any wear as I recall was too much for the trans charge pump, it had to be in near perfect condition. The trans hydraulic controls( under the top cover) used o-rings to seal against the clutch housings(5), and of course many other spots. These will harden with heat especially the buna-n type and lead to loss of pressure and internal leaks. As I recall on the D8H, the converter scavenge pump had to keep the oil level down in the housing, below the converter itself, and a quick check was to drain the housing and measure the quantity of oil in it. The converter charge pump pressure should be checked too. I like the driveshaft check noted above, good idea. If replacing your worn trans pump, the least you could do is drain every compartment holding transmission oil and replace with new. I would not count on the magnetic strainer to remove all metal contamination. Oil sampling would be good to do, when you have your problem fixed. Phil
Okay, thanks AmerIndependent, i might have to take you up on that. We'll see how they look. Phil, does your manual say how much oil the system takes? Also, I know about the screen below the floorboard by the brake pedals, is there another one? Once again I really appreciate all this help, im just struggling through this and learning alot in the process. Oh and I should probably mention that the trans pump I ordered is an aftermarket part that CAT sells, a new one was over $2k and a reman about $1,200. This aftermarket one they sell has the same 6 mo. warranty as the genuine Cat part and was just over $700. Since the dozer is pretty old, I thought the aftermarket one was the best bet.
D6c takes 24 gal for trans There's a second screen in the bottom of the flywheel housing. Here's a couple of scans from the Maint. manual
I would still say put a new pump in it, replace the filter and clean the screen. Use air and a lot of brake clean. The air will blow the stuff off the magnets (wear goggles) . Run it for an hour, clean the screen again. Do this about three times and it should clear up if nothing else is toast. No pump will last forever, and when it starts to go, the housing flakes off and this allows the oil to spill backward and not get pushed along. This builds heat which accelerates the problem. That transmission is very tough and can take a lot of this until the screen gets full and the metal gets run through the trans which will wear about everything out. Old C's like yours never were known for good cooling so don't be surprised if the temp gauge doesn't go right back up where it was when everything is perfect. Not enough cooling fin area up front (most guys I knew that ran those never payed any attention to the guage). Still that is a great tractor and will do a ton of work. Let us know how it goes and good luck!
D6c10K, thank you very much for those scans. Man that tranny takes alot of fluid! I was actually afraid of that. oldirt, good advice, this is what I wanted, some clear direction from people who know. Probably gonna get back at it next week.
With all due respect to Oldirt, I must disagree with his advice. Pumps DO last virtually forever if they are in a healthy system without contaminates or lack of oil. Secondly the screen should have very little debris on it because a properly functioning power train does not produce measurable amounts of metal. If the screens and filters are clean….great! If they are not however, to clean them of excessive debris and install a new pump seems to me a waste of $700. Also, I would suggest inspecting the old pump before installing its replacement as it too can give evidence as to the source of the problem. Basically there are three types of pump failures: 1. Scoring and discoloration of endplates indicates oil starvation. 2. Even damage of end plates as if the gears where machining their way through them. This is an indication of contamination in the oil which results in abrasive wear. Often the center section (body) will have wear too which will produce a lip on the inner circumference. 3. Sometimes the bushings lose their babbit lining which can cause a failure resulting from service hours and would be the only scenario that I would proceed with the new pump (if the screens/filters are clean). Sorry, I don’t mean to be an alarmist but we have seen this scenario too many times over the years and in this economy nobody can afford to throw parts at a problem without doing a thorough job of troubleshooting.
I will start by saying I don't know about these things at all. I did split apart the old pump and there was no burnt smell. There was some slight scoring in the housing (obviously my estimation of slight is not based in experience, so I might try to get some pics up here for all to see). The gears were not chipped but appeared evenly worn.Could you describe the babbit lining of the bushing? The dozer is old and I have no idea if previous owners have maintained it. I have seen evidence of corners being cut, i.e. silicone being used in place of o-ring and subsequent leaking past silicone, poor wiring etc. In my opinion, and again I haven't seen this before, but the magnetic strainer looks filthy. Lots of small iron filings and some larger shards, i guess I should get it analyzed. Amerindependent, when you say to clean the screens of excessive debris and install a new pump seems to me a waste of $700, what is my alternative? I thought I would just make the best of the situation I have.
i'm sure he'll chime in, but if you don't find out where the metal in the screen is comming from it's just gonna trash the new pump. pictures would be great to see whats in the screen and also how damaged the pump might be to see if it can be fixed.
Here's some pics, when I first said even wear on the gears I was looking at the big ones, the little spline type gears are actually chipped. The picture of the magnetic strainer didn't turn out good, let me know if another would be helpful and I will try again.
Here's some more
And some more.
It looks like you've got problems there with that pump. Like I said, installing a new pump is a waste of money because the new one will likely suffer the same fate. The pump damage is a symptom, not the cause. The bushings are damaged, but not from service hours, they too are the victim's of the debris in the system. The problem with dozer power trains is that the transmission, torque, steering and brakes all share the same oil. When one fails it contaminates all the others and if allowed to progress it can get pretty expensive. That's why it is so crucial to isolate the problem early and thoroughly clean the system. Since you just acquired the machine, you don't have the luxury of knowing how long this has been going on and that can be a real disadvantage. I know this machine is old and not worth pouring a bunch of money into it but you may as well know the truth and then make your decision as to how to proceed. Continuing to run the machine with repeated oil and filter changes and a new pump now and then might be reasonable under the circumstances as long as you understand that one day it will probably just lock up and by then it will be well beyond feasible economic repair given the value of the machine. As rebuilder we see this all the time! Looks like your torque screen is pretty clean which could be good news, but since half the magnets are missing from the power train screen it's going to be difficult to make a decision. Where is the outer screen? It looks like we can save your pump, perhaps the best plan of attack would be to rebuild it and reassemble the machine with clean new screens and filters and plan on monitoring closely.
Thanks once again for your input. The outer screen picture didn't turn out well at all so I didn't post it, but it was pretty clean, looked pretty much the same as the torque screen. How much to rebuild the pump? I said the dozer is old which is true, however from what I can tell and from what people have told me its in pretty good shape, so maybe its worth spending some more money if need be as long as I can afford it. I really want to do the best route, just trying to find out ecxactly what that is. Sounds like I should do the following: Buy new tourque screen Buy new powertrain screen Buy new magnet insert for powertrain screen Buy new transmission breather Rebuild pump Change oil and install new filter element Anything else?
That sounds real reasonable, the more I deal with this machine the more I want to fix it right. Let's just hope the cost doesn't get too high.
Hi there guys. I need some help. I'm a new member on this forum. I've just got a dozer d6c 47J series with power shift transmission.i found a piece of metal trapped in the magnetic screen with some minor debris.it looks like a lock plate for the bolts that tie the planetary gear.i dont know if the bolts untied and and the lock went into the system or something.it runs very well, steers well, shifts perfectly. Can you give me any advice on how to handle this as I dont want to run it if it will damage more parts.thanks.any help will be highly appreciated