Hello everyone on the forum, I'm here for the first time, I've had a CAT 950h for two years, The machine has a problem, There are air bubbles in the gearbox oil, All filters and oils are new in the machine (original CAT) There were also air bubbles before the oil change. The oil was precisely measured and poured into the gearbox (34 liters) What could be the cause?
The quantities mentioned in the O&M Manual are only approximate. You should always fill to the correct level in the sight glass on the transmission. Was the engine running when the photo of the sight glass was taken.?
2nd photo - the engine didn't work all day 4th photo - the engine worked for 20 minutes
Need to see a photo of the sight glass with the oil at normal operating temperature and the engine idling with the transmission in neutral.
I don't have it at the moment, I'll prepare it for tomorrow
Apart from seeing what the level looks like with the engine running it will also give an indication of how much air is in the oil. I assume you are using Cat TDTO oil but what viscosity.?
after checking the pressure there are irregularities
CAT TDTO 30
Service Information System (8) Torque converter outlet pressure 415 ± 140 kPa (60 ± 20 psi) (9) Transmission lubrication pressure 105 kPa (15 psi) (minimum
A full pressure test of the torque converter and the transmission might just reveal something. See attached.
Could this indicate restricted flow in the radiator?
Only these two pressures do not match
They are the only two you mentioned so I could not assume you had tested any or all of the others. Comments/questions:- 1. Converter inlet pressure is measured with cold oil and is a maximum value . With oil at operating temperature it will be lower. 700kPa (101 psi) is probably about right. 2. Did you use a gauge with a maximum scale of 30psi to measure transmission lubrication pressure.? On a 500 or 600psi gauge the lubrication pressure is not likely to register because the value is so low. 3. Did you test any of the other pressures, starting with the pump pressure.? Can you post all the results please. 4. What was the converter outlet pressure with the loader stalled in 4th speed forward against the brakes.?
I used an 870 psi manometer for the measurements, so I don't have a proper manometer 3.Pressure measurements The machine worked for about an hour before the measurements. torque converter intel pressure 900 kPa torque converter outlet pressure 700 kPa Transmission lubrication pressure 0 Transmission oil pump pressure 2700 kPa 4. I didn't measure it I didn't measure the clutches
In that case I think that is why you are not getting a pressure reading for the transmission lubrication pressure. If you were able to get a 30-50psi gauge (200-350 kPa) I think you would find pressure in that system. Inlet pressure is fine. Regarding the outlet pressure. Was it measured with the transmission in 4th speed and the torque converter stalled against the brakes.?
I will try to get a 30-50 psi gauge and measure the lubrication pressure. I will measure the outlet pressure again in 4th gear. I will write when I measure it. Thank you for your help and time so far.
You should do it with the oil at normal operating temperature and the accelerator at full throttle.
Hello, I managed to measure the pressure today and the results are as follows: Torque converter output pressure: 80 psi (In fourth gear with the brakes locked) Gearbox lubrication pressure: 17 psi Before taking the measurements, the machine ran for an hour, then I drove it 5 kilometers at full throttle.
After warming up, the oil level was slightly above the "max" mark. I drained 2 liters of oil and it's above the "min" mark. I'll run it for a while and see what the oil looks like. The third photo shows the level shortly after shutting off the engine.
That's where it's supposed to be. There is a big difference in oil level between engine stopped and engine running. See the attachment.
Does the oil look okay? I think the oil is cloudy, should it be clear?
It does look a bit aerated.
What could be causing oil aeration?
I would say the most likely cause is that somewhere on the suction side is not 100% sealed and as a result the pump is sucking a mixture of air and oil.
Gdzie szukać przyczyny? Uszczelki w miejscach zaznaczonych na zdjęciu zostały już wymienione. I nadal nie wiem, gdzie szukać.
Where to look for the cause? The seals in the areas marked in the photo have already been replaced. And I still don't know where to look.
Is the photo above the transmission from your actual machine.? If so was the entire transmission completely disassembled and rebuilt before installation.?
To tylko zdjęcie poglądowe. Skrzynia biegów jest nadal w maszynie. Na zdjęciu widać miejsca, w których wymieniłem uszczelki.
There is always a possibility that any leak on the suction side of the pump could actually be inside the housing containing the transfer gears. Take a look at the attached parts diagram. Pay special attention to the transmission oil suction screen/magnet assembly (Section B-B).
I disassembled the strainer, and there was no visible damage. I also replaced gasket number 7.
The parts diagram may not show it very clearly but I think there should be an angled suction tube inside the housing. How you would insect it for cracks, etc, I'm afraid I have no idea.
Will the tube be visible in this photo?
It doesn’t appear to be.
We have a 950H, JAD prefix, that we bought from our Cat dealer’s rental fleet with 4000hrs. Was doing the same from day one. Lost plenty of hair chasing external leaks etc. but oil tests were coming back fine. Still doing the same at 6500 hrs, still testing ok so, for now, we’re just sending it.
Nature of the beast maybe.?
I wonder why seals weren't used in the gearbox pump? Maybe there's a leak in the pump?
There is a seal between the pump and the transmission housing. Or are you referring to the absence of seals actually inside the pump.? Maybe it could be an idea to remove/disasemble the pump to look of revidence of any internal suction leakage.
Yes, I mean the seals inside the pump, they are only at the connection between the pump and the gearbox and the hydraulic pump
Can you list what was checked? Would replacing the seals between the pump and the gearbox help?