RTV-X1120D Hydraulic Fluid/System question

[s219]

So I did the 50-hour service on my RTV yesterday, which included changing the two hydraulic filters on the back. The smaller HST filter came off easily and I barely lost any fluid replacing it. The larger suction filter was stuck on beyond belief, and I had to drive a screwdriver through it, multiple times, to get it off. Could barely get one full turn out of it after stabbing and rotating little by little, three times, and the rubber gasket made an awful squeak noise until it broke free -- seems like they must have put it on originally with no lube on the gasket.

Anyhow, in the process of murdering that big filter, I lost a fair amount of fluid. Per the manual, after replacing those filters, the fluid level in the transmission case should be checked and fluid topped off as needed. Well, that particular dipstick (yellow plastic, on the top center of the transmission, under the dump bed) read full and kept reading full even after running the engine. I checked the hydraulic tank dipstick, which is under the passenger seat, and it read very low and took about 2.5 quarts of UDT-2 to come back to full.

I spent some time studying the hydraulic plumbing, and it seems to me that the reservoir is connected to the transmission -- the same line that feeds from the reservoir through the oil cooler loops back to the transmission, plus the control valve lines for the dump bed cylinder come out of the transmission. Seems like it's one big common system, but with multiple dipsticks and a couple of reservoir points.

I guess I am at a loss why the owner's manual says to check the transmission fluid level after the filter changes, but mentions nothing about the tank under the seat. It's as if they are separate systems. I would think someone could get in big trouble if they did what I did, but only checked the transmission dipstick and didn't question things, or know to check that other (more hidden and not obvious at all) reservoir/dipstick under the seat.

Maybe one has to drain or lose much more fluid through the transmission case itself before that runs low and can't siphon off the tank? Any other thoughts or insight? As it is now, I know I lost about 1/2 gallon of fluid based on what collected in the kitty litter box I used to catch drips, and I know I added back about 2.5 quarts, so if I step back and look at it in an overall sense, I should be more or less back to normal.

 

[JRobyn]

I think some factories coat the rubber gasket liberally with paint and then screw it on. Avoids leaks!

 

[ovrszd]

Common that the manual doesn't clearly explain how to check the fluid after changing. Have read instances where owners had to have help to successfully get it right.

Factory installed filters aren't lubed.

 

[coldfingers]

S219,
First of all I want to thank you for pointing this out. I did the same thing last summer, changed the two filters, lost oil with the same filter as you, checked the transmission and it was okay so I scratched my head and went back to using it. I didn't check the oil tank until reading your post, mine was about a quart and a half low. If you look in your book they show them as two separate units as they have two different oil changing hour requirements. The only thing I can think of is they are separate units but look like they aren't, weird as the filters are side by side. I know on my tractor they must share the oil reservoir as there is no separate oil tank. Confusing to say the least. Thanks again, great forum!!

 

[s219]

S219,
First of all I want to thank you for pointing this out. I did the same thing last summer, changed the two filters, lost oil with the same filter as you, checked the transmission and it was okay so I scratched my head and went back to using it. I didn't check the oil tank until reading your post, mine was about a quart and a half low. If you look in your book they show them as two separate units as they have two different oil changing hour requirements. The only thing I can think of is they are separate units but look like they aren't, weird as the filters are side by side. I know on my tractor they must share the oil reservoir as there is no separate oil tank. Confusing to say the least. Thanks again, great forum!!

Well, I am glad this helped someone, plus it confirms something is wrong with the way things are written up in the manual.

 

[DEK]

If you change the hydraulic filters, you need to check the reservoir under the seat. A lot of hydraulic oil can be lost when changing those filters, and that oil is from the reservoir. I read about someone who changed his filters and only checked the transmission dipstick. Apparently he lost enough oil changing the filters that the RTV didn't move very well. He thought the new filters might be the problem, so he put the old filters back on and lost more oil doing so. Checked transmission but not reservoir. Started again and I think he said barely moved or wouldn't move, I don't remember. Anyhow, the oil reservoir lost enough oil with the two filter changes and not being replaced that major damage was done to the drive system. I think the repair was $3000-$4000. Dealer was working to try to get warranty coverage. Always, always check the transmission dipstick as well as the reservoir dipstick under the seat or serious damage can occur.

 

[s219]

If you change the hydraulic filters, you need to check the reservoir under the seat. A lot of hydraulic oil can be lost when changing those filters, and that oil is from the reservoir. I read about someone who changed his filters and only checked the transmission dipstick. Apparently he lost enough oil changing the filters that the RTV didn't move very well. He thought the new filters might be the problem, so he put the old filters back on and lost more oil doing so. Checked transmission but not reservoir. Started again and I think he said barely moved or wouldn't move, I don't remember. Anyhow, the oil reservoir lost enough oil with the two filter changes and not being replaced that major damage was done to the drive system. I think the repair was $3000-$4000. Dealer was working to try to get warranty coverage. Always, always check the transmission dipstick as well as the reservoir dipstick under the seat or serious damage can occur.

Would be super if the owner's manual gave that information instead of directing people to just check the transmission dipstick. I bet many owners don't even know about that separate reservoir tank dipstick, especially as well hidden as it is under the seat tray. It's like the perfect storm waiting to happen. I hope Kubota corrects the owner's manual at some point.