Cat D7F hydraulic oil into final drive casing?

[Grouser]

Hi Guys, is it possible for hydraulic oil to enter the final drive cases on a D7F (94n series)? I have a bad hydraulic oil leak that I cannot find. I have removed the floor plates and cannot see any leaks in the body of the dozer.

The leak is coming from the inside of the right drive sprocket.

The right side final drive case pours out oil when checking the filler cap. The final drive lube has bubbles in it also but only on the right side. We normally fill the final drive cases up to a couple inches below the filler cap so I don't think it was over filled, also it pours out after use and when cooled down.

Trans fluid is good.

Thanks in advance . .

 

[bobin35]

I would say your steering clutch hydraulc valve is leaking into the steering clutch and brake case and you may have a bad seal on your pinion shft where it passes through into the final drive.Does the machine steer ok both directions?

 

[LonestarCobra]

Its been a while since I worked on a D7 of that vintage, but best I remember the oil used to disengage the steering clutches is the transmission oil. It sounds like your spur pinion seal is out regardless. If you are losing hydraulic oil, you may have two problems.

 

[Chris91786]

I just finished rebuilding a military D7F (serial # 61G), and I'm currently rebuilding another one, and there is no way that hydraulic oil could enter the final drives that I can think of. I would check out your pinion seals and your steering clutch hydraulic control valve.

Have you noticed a drop in the transmission oil level?

 

[Balzomedic]

My D6c does the same thing, on the same side. I was told by another operator that it's not harmfull, is that true? Curious to see what kind of suggestions/solutions you'll get here.

 

[LonestarCobra]

I have found that on alot of the older lowtrack machines like the D6c, d, d5, d5b etc, that the vent on the steering clutch case can plug up causing the oil to push into the finals. Some are on the filler neck, and others are on top of the case.

 

[Grouser]

Hey guys thanks so much for taking the time to offer input. Turns out the hydraulic leak was a tilt ram hose that came up inside the dozer arm and crossed over into the machine just in front of the drive sprocket. It was hidden under a beat up cover that I finally removed.

I got caught up in the over-full final drive case and it really threw my thought process off to be something that simple! I thought no way could the gear lube pour out like that after the machine cooled for a couple hours but I guess with the air bubbles from 2nd gear use and with still warm oil it had expanded enough to pour out.

The left side may have been low enough that it did not quite pour out when warm.

So I have learned . . . check the finals only in the morning before use and keep your lube all the way to the bottom of the filler cap and expect that when it's warm it will pour out . .

 

[Balzomedic]

Glad you figured your problem out Grouser! I was sidetracked myself recently, dozer was having a hard time starting, thought it was my glow plugs due to the bad wiring leading to them. It wasn't that at all, I had a fuel leak slowly letting air in the line, and It was sure hard to start sometimes.

 

[Balzomedic]

I don't want to hijack your thread Grouser, but I've got another question, im thinking about what Lonestar said. Lonestar, does the steering clutch have it's own oil, or is it supplied with oil from the transmision? Cause i'm thinking my oil might be low if it's leaking into the final. But of course I've nothing to worry about if it's supplied by the trans and I keep it's oil up. I've still got alot to learn regarding the particulars of how dozers work.

 

[LonestarCobra]

Bolzo, the rear section of the tractor has three compartments. Ther LS steering clutch, the bevel gear case, and RS steering clutch. They are all connected by holes in the bottom of the dividers, and share oil. The trans shares this oil also on powershift models. The transmission pump pulls oil from bevel gear case, then to the magnetic strainer and on down the line to the transmission and steering/brake controls. On the older machines with dry steering clutches, the cross shaft has seals to keep the bevel gear oil out of the steering clutch cases. They will leak sometimes and oil up the brake bands and cause problems there.

 

[rickfind]

I've owned D6C's,thay would pass
trans. oil down into the final drive. There's a big O ring between the two that would get brittle with age. thats all I remember about it .