New Cat 977L Owner - Fluids Question

[Mike-JCB]

Hey Guys, I recently got a Cat 977L that appears to be in great shape!

I’m going to be using it to clear some land my wife and I own, hoping to build a house.

I have just gotten an operators manual from Cat and I had a few questions for you all.

After I bought the machine I checked all the fluids, and the transmission fluid was low, we filled it up and it took about 3 gallons, which I felt like was a lot. The manual says the system takes 24.5, and so maybe this is normal? It’s a pretty dry tractor overall with no major leaks, so I’m wondering why the transmission would be so low? I guess it’s possible it’s been low for some time, but was curious as to whether I should expect some oil loss.

The other question I had is about final drives.

The last thing the seller told me is that they recently drained and replaced the final drives fluid, and that they took 90W gear oil. Thought nothing of it at the time. But now I’m reading the manual, I see the drives actually take SAE 50W.

How big of a deal is that? Should I drain and replace the 90W with 50W?

Thanks guys!

 

[Nige]

Did you check the transmission oil level with the engine stopped or running.?

 

[fest777]

good idea would be too drain the 90wt and get some to-4 50wt in the finals, its a real easy job the plugs are at the back down low, you will see them, i think there 3/4" square, you need a 5 gal drain pan cut low. on the trans it could be leaking past the pinion seal ?, check the steering case oil and see if it is higher than normal, also check the converter input seal for leaks while running,the only other possibility is the steering case suction screen is plugged and pulling the oil from trans to case, that's all for the 955 series and the 977 is almost identical but the 77 has a drive shaft, whats the vintage or ser. # that will really help, good luck anthony

 

[Nige]

The last thing the seller told me is that they recently drained and replaced the final drives fluid, and that they took 90W gear oil. Thought nothing of it at the time. But now I’m reading the manual, I see the drives actually take SAE 50W.

Maybe I can shed some light on this. The viscosity of Gear Oils like the 90 (it's only "W" up to 85) the seller spoke about are measured not surprisingly on the SAE Gear Oil scale.
The SAE50 (not 50W, there is no such thing) recommended in the manual is measured on the SAE Crankcase Oil viscosity scale. See the illustration below.
In terms of absolute viscosity there is very little difference between a 50 and a 90.
As Fest said above, the SAE 50 recommended for the finals should be a powertrain oil that meets Caterpillar TO-4 specification, or Caterpillar TDTO if you buy the oil from the Cat dealer.
Apart from certain limited exceptions Cat never recommended Gear Oil in finals because part of the GO additive package is known to attack the silicone rubber rings in face seals and can cause them to leak.

 

[Bluox]

AAH 50w transmission oil has been around for years.
Cat has used GO 90 in finals diffs and direct drive transmissions from the get go .
In fact they still use it in a lot of final drives.
When TO-4 oils came out for PS it could be used finals.
GO is not used in finals with frictions.
Bob

 

[Mike-JCB]

Thanks guys this is super helpful. Learned something about oil viscosity today. It makes sense now why the seller said they used 90W. So because they used 90W and it has the same viscosity as SAE50, we should be good as is?

Nige- to your question on the trans, we checked it with the machine off and cold.

The serial for this machine is 11K5780.

 

[Bluox]

Hey Guys, I recently got a Cat 977L that appears to be in great shape!

I’m going to be using it to clear some land my wife and I own, hoping to build a house.

I have just gotten an operators manual from Cat and I had a few questions for you all.

After I bought the machine I checked all the fluids, and the transmission fluid was low, we filled it up and it took about 3 gallons, which I felt like was a lot. The manual says the system takes 24.5, and so maybe this is normal? It’s a pretty dry tractor overall with no major leaks, so I’m wondering why the transmission would be so low? I guess it’s possible it’s been low for some time, but was curious as to whether I should expect some oil loss.

The other question I had is about final drives.

The last thing the seller told me is that they recently drained and replaced the final drives fluid, and that they took 90W gear oil. Thought nothing of it at the time. But now I’m reading the manual, I see the drives actually take SAE 50W.

How big of a deal is that? Should I drain and replace the 90W with 50W?

Thanks guys!

The 90 gear oil will be fine.
Check the oil level in the final drives if they are way over full that may be where the transmission oil went.
Most of the time you don't notice oil transfer till you change the final oil.
Check the transmission with the motor running.
Good luck
Bob

 

[Nige]

Nige- to your question on the trans, we checked it with the machine off and cold.

It should be checked with all systems at normal operating temperature and engine idling with transmission in neutral. That could explain what you saw on the stick when you checked the level.

 

[Bluox]

It should be checked with all systems at normal operating temperature and engine idling with transmission in neutral. That could explain what you saw on the stick when you checked the level.

If the oil level is correct and you check the oil with the motor off it will show overfull.
Bob

 

[fest777]

what i was concerned about is if the 90 was a gl-4 or 5,from reading this is not good for cat finals, i should have asked if it is in fact gl-4/5.hence suggesting a change of fluids to a to-4 spec oil, conoco 66 is priced good, even cat oil at certain times is priced right, mobile is like out of the question something like $110.00 for 5 gal bucket,

 

[Bluox]

what i was concerned about is if the 90 was a gl-4 or 5,from reading this is not good for cat finals, i should have asked if it is in fact gl-4/5.hence suggesting a change of fluids to a to-4 spec oil, conoco 66 is priced good, even cat oil at certain times is priced right, mobile is like out of the question something like $110.00 for 5 gal bucket,

You know everything you read on the internet is the truth right?
That machine may have came with 90 in it that's about the time TO-4 oils came about.
If the guy that had it been running it must not be too bad.
Bob

 

[Mike-JCB]

Thanks guys. Now I’m worried me filling the trans fluid will be overly full because I didn’t read it properly! Ahh

 

[fest777]

the trans level will normally go lower when checked running and in low drive, but it can also increase the hotter its gets, 1 or 2 gallons over on a large loader like a 977 wont kill it ,some operators like running a gallon over, check it warm,if its way over try taking a gear pump attached too a 3/4" hose and ram it down the fill tube and pump a little out,unless there is a drain plug on the bottom of the skid plate, some have them for the case and trans

 

[charles walton]

I like to run the trans oil on PS loaders a little over because I get it in extreme angles quite frequently.

 

[Mike-JCB]

Hey Guys - I ran the Cat over the weekend and this thing is a beast, I got a ton done. But the bad news is after I was done today, I noticed that my right final drive had some drips on the inner track. Not yet a severe leak but when the machine is hot it’s definitely got a small leak.

From reading in these forums I know that this can become a big deal if it’s not taken care of over time. Here’s my question.. how big of a deal is this right now?

I’m trying to clear a 4 acre field over the next few weeks so I can plant some clover/winter wheat to get through winter. I have other things to do with the machine and will get this fixed, but can it wait? Or is this a, do not drive the machine until it’s fixed type deal?

Also this is outside my wheelhouse and not something I can do myself. To replace that duo cone seal, what does that cost? Or what should I expect to pay?

Any other advice would be great. Thanks!

 

[Bluox]

You need to get a service manual.
If the sprocket bearings get worn you can sometimes adjust them and cure a leak.
You can check for a loose bearing with a 6 ' bar ,stick the bar in the sprocket and pry against the track frame.
You might call the nearest Cat dealer and ask if they have a number for a independent who can handle the job.
Good luck
Bob

 

[charles walton]

If you will buy a service manual and adjust the bearing preload you will probably be able to run a good while if it is not leaking bad.

 

[Cat977]

Bob could be onto something. Back at the Power Plant I replace a few bearing that had inboard seals similar to a duo cone seal. It sometimes took a few weeks to have the leak totally stop, but it was cheap and easy!!!
Best of Luck