Caterpillar 247B3 Leaking final drive or planetary. Does it need to be fixed?

Hello. I have a Cat 247B3 with 980 hours and I noticed that one of the final drives or planetaries is leaking. I suspect it's the drive as the planetary doesn't seem to be losing fluid. It does not leak very much. I only put about 50 hours a year on the machine. Is it safe to operate with the leak or should it be repaired?

Thank You!

I fixed a leak similar to that a few months ago. Blown oring on a plug, back of the motor

It appears as though your leak is coming from the drive motor if your photos are taken looking at where the red arrow is pointing. That motor has a Duo-Cone seal inside it and they like being kept moving. By any chance did you first notice the leak when the machine had been standing for an extended period if you're only using it 50 hours a year..?

That is hydraulic fluid. Your tank holds close to 15 gallons. Just run it, keep an eye on it and the hyd. fluid level.

ianjoub said:

That is hydraulic fluid. Your tank holds close to 15 gallons. Just run it, keep an eye on it and the hyd. fluid level.

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Be aware though, that if fluid can get out, dirt can get in. I have no idea what underfoot conditions you operate in.

Nige said:

It appears as though your leak is coming from the drive motor if your photos are taken looking at where the red arrow is pointing. That motor has a Duo-Cone seal inside it and they like being kept moving. By any chance did you first notice the leak when the machine had been standing for an extended period if you're only using it 50 hours a year..?
View attachment 199731

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Yes, that's exactly where it is leaking, and yes, it does sit for pretty extended times between uses. I probably didn't run it at all from January till this month. What kind of job is it to replace the seal? Something I could do myself?

Thanks You!

It might not even require the seal to be replaced. Good bearing adjustment (it's done with shims) will often fix a weeping seal like yours.
Going into one of those drive motors is not a job for the uninitiated - see below. The seal is #10 (circled)

Nige said:

It might not even require the seal to be replaced. Good bearing adjustment (it's done with shims) will often fix a weeping seal like yours.
Going into one of those drive motors is not a job for the uninitiated - see below. The seal is #10 (circled)
View attachment 199773

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Definitely doesn't look the easiest. With the small seep, how much risk do you think it is to run it as is? Any thoughts on how much a cat dealer would charge to replace the or shim the seal? It looks like it may be cheaper to replace the entire drive.

Knowing how these seals function personally I would have no problems digging into that drive motor assembly, but ........
The Cat dealer wouldn't want to spend possibly who-knows-how-many hours digging into it and checking/adjusting the bearing preload to maybe have it still leaking when it was reassembled. They would want to replace the seal assembly ($300 give or take) as an absolute minimum in order to give a warranty on the repair. They might want to replace other parts as well. With dealer labour at maybe $150/hour all of a sudden you're talking real money.
You might be better advised to have a qualified independent mechanic with hydraulic drive motor experience to have a look at it. I have no idea what's available in your area.

Just to remove any possibility that it might be no more than a piece of dirt in between the two rings of the face seal why not try operating the machine for an extended length of time (half a day maybe?) and get things really hot, then park it and see what happens to the leak.

Nige said:

Just to remove any possibility that it might be no more than a piece of dirt in between the two rings of the face seal why not try operating the machine for an extended length of time (half a day maybe?) and get things really hot, then park it and see what happens to the leak.

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I seem to recall a 769C truck at the quarry that developed a leak form a wheel seal while parked over the winter. But after washing machine thinking we would be pulling the rear wheel off found that the leak disappeared and ran the full season with no more leaking!

I cleaned everything up and ran it a while yesterday. After an hour, there was 1 drop on the rail. After 5 more hours and sitting overnight, still just the one drop, so it looks like it may have stopped leaking. I'm going to clean it up again and see if it leaks anymore.

Aside from holding dirt out, does this seal hold pressure on the hydraulic side, or gear oil on the planetary side or neither? If it does leak dirt in, is there risk of getting dirt into the hydraulic system or just the planetary?

That seal keeps the planetary oil from falling out and dirt from the outside getting into the planetary. It’s not connected to the hydraulic system in any way.

If by running the machine you can get the deal to quit leaking then maybe at that point might be the time to change the oil in the planetary.

If you want more info about these deals and how they work, do a search on here for “Duo-Cone seal”

Nige said:

That seal keeps the planetary oil from falling out and dirt from the outside getting into the planetary. It’s not connected to the hydraulic system in any way.

If by running the machine you can get the deal to quit leaking then maybe at that point might be the time to change the oil in the planetary.

If you want more info about these deals and how they work, do a search on here for “Duo-Cone seal”

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OK. Thanks so much for all the info! The planetary oil only has about 8 hours on it now. I replace it every fall which ends up being every 50 hours or so.

Joshs I have the same leak on my 247b2...what happened with yours? Thanks

Blue247b2 said:

Joshs I have the same leak on my 247b2...what happened with yours? Thanks

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After a while of using it, it has seemed to seal back up.