I looked at a D6D today, serial number 4x1220 and found that the left final drive which is seeping was overfull of oil (it ran out when I removed plug) and the oil seemed very light compared to the right hand final drive. Is it possible for the hydraulic oil to get into the final drive? I'm just beginning to learn about how these dozers are put together. Also, the left hand steer lever/brake was hanging up and you needed to push it in after releasing it; what is the most likely cause of this? Also, what year is this dozer, he thinks it's a 1977. Thanks to all who have replied to my requests for info on different dozer's. Your advice/information has been a big help. Dan
Oil is transfering from the steering clutch case to the final drive. Clean and lube the linkage pins. Later Bob
Thanks for the reply Bob. I'm assuming that the two sentences are two seperate answer's; the first obviously for how the final drive is getting hydraulic oil in it and the second being what to do about the steering lever hanging up! A follow up question on the first problem is how big a deal is it to fix the oil transfering through the steering clutch? I'd love to see a parts book on this thing to see how it all goes together as I've never been around a dozer being worked on in the rear end.
Dan, you need to lift out the steering clutch, should do both and reseal the FD Pinion flanges. Likely just replace the orings not the duo cone rings. Take off fuel tank, then covers the pinion flanges need pressing off and back on. Later Bob
For the pinion seal you have to pull the top off the bevel gear case, pull the steering clutch & brake band, then pull the driven hub off the pinion shaft with hydraulic puller to access duo-cone seal. (hub pressed on at 20-25 tons and torqued to 700 ft lb.)
Bob dosen't that final drive use 30wt also same as tranny? Youknow what i am thinking. DR I will try to scan some pages of my parts book for you.
Are you looking to buy this dozer? If so, maybe someone could give an idea of what it would cost to repair. I would be curious if that seal is known to fail or if the bearing is out on the pinion shaft and caused the seal to fail. None of this would make me run from the dozer but would affect what I would pay for it.
Good point...the seal probably failed for a reason....while I was in there I would fix anything that was marginal.
It has been a long time since i've gone into one of those but as I recall the final drives are supposed to run 50 wt. while the transmission runs 30 wt. There is no way for hydraulic oil to get into the final drives. There is a lip seal on the pinion gear from the steering clutch into the final drive. The part I don't recall is whether or not you have to pull the final drive to get to the seal. As I recall on the D8 and 9 machines the seal carrier was bolted into the inside of case of the steering clutch. I could be wrong so you better get a book with the correct information. The steering clutch will definitely have to come out for access. That entails pulling the fuel tank, the clutch / brake cover and unbolting the clutch. You need a book for that job or someone who has done it before. I have had machines that transferred oil before and since money was tight we did nothing with them. The final will fill up with oil to the transmission level and not hurt anything as long as the bearings are OK. The steering clutch and brake levers have a support shaft under the deck plate that has needle bearings in them. There are no grease fittings for them so eventually they fill up with dirt and get stuck. You can take them apart, which a bit of a pain, and clean them up. Coat the bearings with anti-seize and put back together. It should be good for years after that. Good Luck!
if the final is leaking to the outside, the bearings are loose enough to ruin the seals, and it all needs to come apart for at least new bearings and seals, requiring the cat hyd press/puller as it will take 60-80 tons to get the sprocket and flange off, 35-45 tons to put it all back. As has been said, pinion seal/bearings are shot as well, and it comes out the top side after you pull out the steering clutch assy. That is an early model, serial break was around 7200 or something for the 4X. You need to know how many hours are on the cross shaft, other final, and trans/torque since last rebuild. If the seals go out on the cross shaft the steering clutches will quit functioning. This stuff all lasts a really long time but when it is done you really need to get it repaired.
It doesn't sound like this is a dozer to bring home and put to work. I think I'll pass on this one and keep looking. Thanks to all for sharing your thoughts/experience with a rookie on dozers! I'd still love to see those pages Shopguy, if you want to take the time to scan them. Dan
a quick followup question regarding the wt. of fluid in the finals... the left one that is overflowing looks/smells like hydraulic oil, the right hand final has what could only be 140wt oil in it and it's making me wonder if someone filled it with the heavier grease to cover up a leaking seal on it also. I checked for play in the sprocket hubs and both seemed good, no play that I could see when prying on them with a bar. Any thoughts on this??? Anyone ever ran into this before?
It's pretty common to use 90wt in the final drives instead of the 50wt Cat specs show. Sounds like it might have just one side leaking and that would account for the different oil in each side.
Well I think D6c10k and john c have good have good points , i would not let final drive level to cause me to not buy a tractor if you needed that size dozer and that is all you can find wrong with one that old i would buy it and keep everything checked and run it, As John said I have had machines that transferred oil before and since money was tight we did nothing with them. The final will fill up with oil to the transmission level and not hurt anything as long as the bearings are OK.
Final drive over filled oil level on D6C/D tractors is usualy blamed on the top pinion shaft Duo Cone seals, but its often the intermediate gear housing causing this oil transfer, the F/Drive steel breather pipe can also be an issue, the fact that the spocket seals (Duo Cone) are letting oil past regardless of the oil levels indicates that the hub needs the dead-shaft nut checking and the hub pre load adjusting, these seals dont leak unless there is slack in the pre-load or they are damaged ether from wear or otherwise, I once had a D6 F/Drive with engine anti freeze in it?? the transmission oil cooler had failed, also the inter' bearing housing had smashed up letting A/Freeze into the final case, there is plenty of people that use 85/90 gear oil in F/Drives the service plate indicates SAE 30 S3 as a more prefered oil, the latest thing now is TDTO 50 oil this is a new oil that is found a better product that things that were about 25 years ago, I still manage to do about 8 or 10 F/Drives a year on standard style CAT tractors and still enjoy doing them.
DRieff, I was looking on craigslist and saw a D6C 10K near me. Thought I would tell you about it. Then I looked at the pictures and saw the brass spittoon. On to this D6D, every dozer I've bought needed something fixed or resealed. It just needs to be reflected in the price. Sometimes you can get a heck of a bargain that way.
at the age all these girls are you have to expect to do something to them. The point is eventually when you,ve gone through every/ or most things ! You at least know what youve got. And the beauty of D6C/D is that plenty of parts are always available; be they new cat, cat classic, pirate and 2nd hand. They wi;; still do a good hard honest days work, and there is no electrical ******** to put up with. Biggest question is how clever you are with spanners, and if not do you know some one that really is, and how much does he charge. Yes alot boils down to the maths with it all. Have 2 D6Ds D4E and D of my own, all were got for various reasons, and price was in most cases right. don,t really need all of them, but they are differently spec,d for different jobs. rippers, winch,scraper, bull blade,angle blade. TC is also correct in that they can leak from the intermediate f/d brg housing. there is a o ring in there than can go hard over time. As well as the pinion drive flange cork seal and/or duo cone seal. Still a great classic machine, love mine.