Hydraulic oil in eng oil

[TC 35D owner]

TC35D replaced three hoses and a hydraulic cylinder. Checked fluids and refilled as needed. I started working machine and backhoe was digging but with reduced power for a bit. Friend started using backhoe and said he heard “a noise like something break”. I know- not very descriptive but best I could get. Power improved but now dumping hydraulic fluid into oil as evidenced by oil overflow tube blowing out oil/hydraulic mixture and engine oil now showing overfilled and with the same mixture.
So- I have an idea what the problem might be but want educated (cause I’m a novice) opinion and suggested repair.
Thx is in advance.

 

[Roadworthy]

It sounds like your hydraulic pump is leaking into the crankcase. It is powered directly from the engine and sometimes they leak.

 

[JC-jetro]

Most likely place for the leak would be hyd pump shaft seal. It is double lipped seal on the pump input shaft.

 

[TC 35D owner]

Most likely place for the leak would be hyd pump shaft seal. It is double lipped seal on the pump input shaft.

Thanks. That’s what i was guessing from reading up. Do you know if a replacement seal installation is difficult?

 

[TC 35D owner]

Thanks. That’s what i was guessing from reading up. Do you know if a replacement seal installation is difficult?

And is it just a coincidence that this blew with an hour of operation after I replaced 3 hyd hoses and a hyd cylinder? Or could the replacements created a problem and tvs seal will blow again?

 

[JC-jetro]

Thanks. That’s what i was guessing from reading up. Do you know if a replacement seal installation is difficult?

No. It is pretty easy but you need to be careful and not rough with removal. I have a few pics below FYSA. For just shaft seal replacement you do not need to do pump disassembly but you do need to remove the pump. You need to remove the nut on the shaft while holding on to the gear in a vice sandwiched between couple of pieces of wood to avoid damage to the gear. The shaft seal has a snap ring that seats in an internal groove. Need to use a pick and remove the shaft seal, that will destroy the oil seal completely. Clean the shaft and the groove well. Use a deep socket that fits the dia of the new seal, lube the shaft and seal and slowly but firmly drive the new seal. This is a one time deal.Make sure the seal is nice and square to the shaft. After that put the spring loaded retainer ring and make sure it is fully seated in the groove and then put the pump back.
JC,

 

[JC-jetro]

And is it just a coincidence that this blew with an hour of operation after I replaced 3 hyd hoses and a hyd cylinder? Or could the replacements created a problem and tvs seal will blow again?

My seal also looked good but was not making pressure so ended up doing it after pump overhaul. Gear pump is a positive displacement pump unlike a centrifugal pump. You can not dead head a gear type pump and the seal is path of least resistance. If you have a pressure gauge use it and see what pressure you are developing.

 

[TC 35D owner]

No. It is pretty easy but you need to be careful and not rough with removal. I have a few pics below FYSA. For just shaft seal replacement you do not need to do pump disassembly but you do need to remove the pump. You need to remove the nut on the shaft while holding on to the gear in a vice sandwiched between couple of pieces of wood to avoid damage to the gear. The shaft seal has a snap ring that seats in an internal groove. Need to use a pick and remove the shaft seal, that will destroy the oil seal completely. Clean the shaft and the groove well. Use a deep socket that fits the dia of the new seal, lube the shaft and seal and slowly but firmly drive the new seal. This is a one time deal.Make sure the seal is nice and square to the shaft. After that put the spring loaded retainer ring and make sure it is fully seated in the groove and then put the pump back.
JC,

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Thanks for taking the time to give me a great explanation and the pics.
Have a great weekend.

 

[JC-jetro]

Thanks for taking the time to give me a great explanation and the pics.
Have a great weekend.

You're welcome. You too. Let us know how your repair is progressing and if we can help more.

 

[DwayneB]

Usually never just the main shaft seal. The internal seals hold the pressure.
Sounds like the relief valve on the backhoe may be set higher than your pump can handle.