Hi Folks, It seems I have to change out the seal group on my d8k, and possibly other parts. Just bought this machine locally, in Yaounde, Cameroon, Central Africa. During our first maintenance, we were checking the condition of the hydraulic oil on one side of the hydraulic reservoir near the sprocket. We opened the reservoir cap and realized that the transmission oil was leaking into the hydraulic oil section. Transmission oil was literally gushing out. Has anyone here done this before? Just how complicated is this, and what parts do I have to change out? ie Are there additional seals and gaskets I would need to change once I have opened the machine up? Given that this seems like quite an exercise, would this affect the condition of the final drive?
I think you are trying to say "trans oil going into the final drive" If so the steering clutches need to come out and the final drive pinions need to be resealed. Lots of heavy lifting and press tools. Later Bob
That's right Bob, Transmission oil is going into final drive. So we need to replace the damaged seals. Seems like a tedious and time consuming exercise. Any tips on how best to go about this? Any precautions one must observe while doing this?
Remove everything down to and including the fuel tank. Remove the steering clutches and check the stack height and brake lining as well as the bevel gear shaft bearings for side movement. I think the FD pinions and flange will all come out assembled. You need a press and some tooling to remove and reinstall the flanges. Some one will have spec to press the flange on to and nut torque. Be sure to do both sides while you are in there. Later Bob
If you take a look at my CAT sprocket pulling thing in Shop Talk page 14ish might be of interest, but dont think the top pinion seals are the single cause of oil transfer, the problem can be caused by other issues, most D8K's gush out oil from the F/Drive case, it is sometimes best to wait for a need to go into the back case like worn Brake Bands etc, fit new copper washers on the F/Drive oil level plugs and get some work out of the chariot, to much oil is a lot better than no oil, the work to get things in bits plus all the tooling is a problem to sort, I do this type of work constantly so I know there is drama ahead, the pinion nut size is 3" A/F also the top pinion and flange on D8s can be removed as 1 item to use a shop press for replacement of the Duo-Cone seals, its hard to know the point to stop after you remove the Fuel Tank. keep it rolling, tctractors p.s. Shop Press = No fancy tooling, just your brain???
Most of those old machines leak oil between the final and the main frame cases. It doesn't hurt a thing. The seals between the cases don't seem to last as long as the bearings and gears. Opening up the steering clutch on an old dog like that to me is like lifting the lid on a coffin. You are likely to find a lot of expensive old bones. If there were no big pieces of steel in what you drained out of the final and the machine is still operating properly I would suggest as tctractors has stated, fill everything back up and put it back to work.
Hi tctractors, Thanks for your response. I wish I could say I am experienced at this but I am not, so I am getting some help locally, while trying to learn as much as I can about it all. So I am looking at all those pictures you referred to with the eyes of a novice , Actually, I was advised that it would be better to go in and sort it out now otherwise it could get worse by damaging the transmission system drives, etc. Plus they said it would be good to change both (just like Bob said) because we don’t know the pressure the previous mechanic used when pressing the other side previously. If I continue to use the machine for a while yet, what would be the point at which I stop? How would I know when I am at that point?
Hi John C, Thanks as well for your response. It's an interesting take on this problem. Apart from particles in the oil, is there anything I could look out for as a sign that there are problems if I decide to keep working with the machine?
Here are the pics showing the initial leaks around the hydraulic fluid reservoir caps.
Have you pulled the final drive filters and cut them open?
Madozer, you might just be getting the wrong advice from your man that gives advice??? the final drive outer bearings are usualy marked up some after around 1'000 hrs but can still manage massive hours, if you think the top pinion seals are the cause of the oil transfer you might well be looking at the wrong spot, I have seen these seals totaly knackered and loose in the housing without any oil transfer found, its your money you spend it as you need to, it might help some to start at page 1 of my thread so you dont think I am full of crap? best of luck, I wish you were in the U.K. as I would love your coins. tctractors
No, I haven't, John.
Hi Tctractors, I am here to garner some knowledge and I have read enough of your posts to know you are one of the most experienced guys here who are also willing to share their knowledge. So I am taking your feedback seriously. Unfortunately I don't have the maintenance records for this machine, and you are quite right that I could be getting the wrong advice from this side. One question is, how do I manage the situation going forward, if I decide not to change the seals just yet? Simply keep a close eye on the transmission oil level by checking on it daily?
Yair . . . madozer . It sure looks like those final drive level plugs are just leaking. They will have "O" rings or copper washers to seal them, I disremember which. One thing that threw me was your use of the term "hydraulic fluid" and hydraulic "reservoir". "Hydraulic" is normally associated with blade and ripper lift and various systems on machines such as brake boost and steering clutch release . . . what you have is a gear case containing the final drive components that I think these days run in a light gear oil although when that era tractor were in production Caterpillar recommended engine oil in all compartments. As John C suggests I would check those filters and if you are concerned about the metal drop the drain plug out for a moment with an old fry pan or some such underneath the housing to catch any bits and teeth . . . do it cold and you can poke a finger in there to have a scrape around, you can usually get the plug back in there and won't lose all the oil. tctractors has been very helpful to other folks and I am sure he will help again if you have major problems . . . be assured though that final drive work on a D8 is a major undertaking for a newby and you will need some specialised but fabrictable in the bush bits and pieces of tooling. Cheers.
I would change all filters, clean screens, set oil levels where they belong and run it a day, check levels and proceed, oil samples are good after several are taken to get a starting point. Put some new seals on all the fill and drain plugs. If I were going to follow one mans advice on this it would be TcTractors.
The F/Drives will take oil from the steering case untill the levels match, all you have to do is add oil as needed to the trans/steer case, if you press lightly on the brake peddle under movement you will detect any brake drum dance, if the peddle feels constant things should be good, as I said in my first post fit new copper seals to the F/D oil fill plugs and top up the steer case SAE 30 or TDTO and get some work out of the beast, on D8's the only oil samples worth taking are from the engine, all the other areas set free "Glitter" its just knowing the amount that things get done at??? if you are mad keen to see inside the beast (I would be, its what I do) crack on and pull the fuel tank, I can offer plenty of tips to help. tctractors
Keep it going.If oil starts coming from somewhere else,then it's time to investigate. Iv'e had 8/9 D8's in the last 25 years and never lost a final drive through pinion seal transfere ......yet!.It doesn't worry me at all.Top pinion seals often go brittle and hard and start leaking.I once lost drive on a D8 one day and pulled the screen under the filter to find an almost in tact seal which I guessed could only be from the top pinion.It was hard and brittle and had caused a fair bit of oil to dump out of the tranny causing ocassional gear loss.I simply fired a load of oil into the tranny and put it back to work.I chucked the remaining seal into the bin and ran that tractor for another couple of busy years before shipping it to Africa.I still know the owner and it's still going.(don't know how many hours it clocks up though) Your tractor might(and I stress 'might') carry on for years. On D8's,there will be plenty of other things to worry about than transferring final drives!!