RTV 1100C Transmission oil in engine

Grayducks

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B7800 - RTV 1100c
Jun 7, 2024
8
1
3
North Carolina
Transmission oil is filling up the engine crankcase. I've been watching this for a year or so and as the trans oil goes down the engine oil goes up. There are no external leaks and all fluids and filters have been changed twice since this started. Both local dealer mechanics say this can't happen based on my description but have not had it in the shop. Looking for direction before it blows up.
 

TECH101

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Kubota - Bobcat - Caterpillar - Case - John Deere - FARM - CONSTRUCTION -
Mar 8, 2022
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I would start by removing your drain plug on the bottom of your bell housing, there should be no oil in there.

Let me know for next steps
 

whitetiger

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Kubota tech..BX2370, RCK60, B7100HST, RTV900 w plow, Ford 1100 FWA
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Transmission oil is filling up the engine crankcase. I've been watching this for a year or so and as the trans oil goes down the engine oil goes up. There are no external leaks and all fluids and filters have been changed twice since this started. Both local dealer mechanics say this can't happen based on my description but have not had it in the shop. Looking for direction before it blows up.
What is the exact full model number of your RTV?
 

Grayducks

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B7800 - RTV 1100c
Jun 7, 2024
8
1
3
North Carolina
I would start by removing your drain plug on the bottom of your bell housing, there should be no oil in there.

Let me know for next steps
In the past oil has leaked from the starter bolts and the vent tube needed cleaned. I will pull the plug bell housing tomorrow. I did pull two quarts of excess oil from the crankcase yesterday to get the level to normal. I will drain and replace the engine oil before starting.
 

TECH101

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Kubota - Bobcat - Caterpillar - Case - John Deere - FARM - CONSTRUCTION -
Mar 8, 2022
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In the past oil has leaked from the starter bolts and the vent tube needed cleaned. I will pull the plug bell housing tomorrow. I did pull two quarts of excess oil from the crankcase yesterday to get the level to normal. I will drain and replace the engine oil before starting.
Yes exactly.... There should be zero oil coming from the starter bolts meaning your seal has damage and is leaking

You have to separate the engine from transmission to replace. I would do both engine and transmission seals.
 

whitetiger

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RTV-X1100C S/N 21586
Ok, your RTV-X1100c is a completely different model than the RTV-1100c you have listed.

Are you losing oil from the trans-axle behind the engine or the hydraulic tank below the passenger seat?
 

lugbolt

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ZG127S-54
Oct 15, 2015
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a failing hydraulic pump will fill the crankcase with hydraulic fluid.

I'd think that if the charge pump in the bellhousing were leaking, it'd fill the bellhousing but unless the rear main seal on the engine were leaking, hyd oil couldn't get into the crankcase from there--at least I don't see any other way it could.
 

whitetiger

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a failing hydraulic pump will fill the crankcase with hydraulic fluid.

I'd think that if the charge pump in the bellhousing were leaking, it'd fill the bellhousing but unless the rear main seal on the engine were leaking, hyd oil couldn't get into the crankcase from there--at least I don't see any other way it could.
There is no charge pump in the bell housing, it is at the rear of the machine.
 
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Grayducks

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Equipment
B7800 - RTV 1100c
Jun 7, 2024
8
1
3
North Carolina
Yes exactly.... There should be zero oil coming from the starter bolts meaning your seal has damage and is leaking

You have to separate the engine from transmission to replace. I would do both engine and transmission seals.
I drained about a pint of oil from the bell housing. I agree that the seals are the most likely source of the problem.. Any idea of the cost/complexity of replacing them?
 

Grayducks

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Equipment
B7800 - RTV 1100c
Jun 7, 2024
8
1
3
North Carolina
I drained about a pint of oil from the bell housing. I agree that the seals are the most likely source of the problem.. Any idea of the cost/complexity of replacing them?
I do have the 72" commercial snow plow setup. I remember the dealer having to install a pump for that system. They are researching that and I can't find anything in the usual parts diagrams.
 
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woodman55

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L6060HSTC, RTV 1100
May 15, 2022
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canada
I do have the 72" commercial snow plow setup. I remember the dealer having to install a pump for that system. They are researching that and I can't find anything in the usual parts diagrams.
Is the plow Kubota, or a after market brand like boss ? That may be why you can't find anything on it.
 

TECH101

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Kubota - Bobcat - Caterpillar - Case - John Deere - FARM - CONSTRUCTION -
Mar 8, 2022
69
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I drained about a pint of oil from the bell housing. I agree that the seals are the most likely source of the problem.. Any idea of the cost/complexity of replacing them?
In the shop we would quote out
I drained about a pint of oil from the bell housing. I agree that the seals are the most likely source of the problem.. Any idea of the cost/complexity of replacing them?

Real time do it yourself first timer maybe a week time of work, All depends on the person I guess

You'll need some jack stands and a jack for sure, separating engine/hst from frame. Not too bad
 

TECH101

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Equipment
Kubota - Bobcat - Caterpillar - Case - John Deere - FARM - CONSTRUCTION -
Mar 8, 2022
69
15
8
Canada
In the shop we would quote out



Real time do it yourself first timer maybe a week time of work, All depends on the person I guess

You'll need some jack stands and a jack for sure, separating engine/hst from frame. Not too bad
 

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Grayducks

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Equipment
B7800 - RTV 1100c
Jun 7, 2024
8
1
3
North Carolina
Thanks for your information.. The RTV has an additional hydraulic pump that appears to be mounted to the engine block behind the injector pump. Most likely to power the Kubota 72" commercial snow plow. I'm going to see if it might play a role in all this.
 

whitetiger

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Nov 20, 2011
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Kansas City, KS
Thanks for your information.. The RTV has an additional hydraulic pump that appears to be mounted to the engine block behind the injector pump. Most likely to power the Kubota 72" commercial snow plow. I'm going to see if it might play a role in all this.
The power steering/bed tilt pump is mounted behind the injection pump. If an auxiliary hydraulic package is added, that pump is replaced with a tandem pump. The front section supplies the steering and dump bed & the rear section supplies the auxiliary hydraulic control valve.
This pump draws hydraulic oil from the reservoir under the passenger seat.

if you are leaking oil from the transaxle into the bell housing, check the vents on top of the transaxle. If they are plugged it will push oil past the transaxle input shaft seal into the bell housing.
For the oil to get from the bell housing into the engine crankcase, the bell housing would have to fill up to the height of the rear crankshaft seal and be pressured higher than the engine crankcase pressure.

The transaxle oil is just for lube, there is no pump. The hydrostat is mounted to the rear of the transaxle assembly and it draws oil from the reservoir under the passenger seat.
 

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Grayducks

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Equipment
B7800 - RTV 1100c
Jun 7, 2024
8
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3
North Carolina
Thanks whitetiger and TECH101. You are confirming what I am figuring out. The double pump I have isn't causing my problems because the under seat tank isn't loosing fluid. I may have a bum trans input shaft seal. I cleaned the trans vent but nothing came out. I'll drive it for a few days then drain the bell housing again to see if it is gaining fluid.
 

TECH101

Member

Equipment
Kubota - Bobcat - Caterpillar - Case - John Deere - FARM - CONSTRUCTION -
Mar 8, 2022
69
15
8
Canada
Thanks whitetiger and TECH101. You are confirming what I am figuring out. The double pump I have isn't causing my problems because the under seat tank isn't loosing fluid. I may have a bum trans input shaft seal. I cleaned the trans vent but nothing came out. I'll drive it for a few days then drain the bell housing again to see if it is gaining fluid.
No worries anytime just let me know
and remember to keep it simple