Overfilled hydraulic fluid

[hatchet]

I just bought a 1979 721 bobcat .I checked the hydraulic fluid and it was pouting out.I drained out about 6 gallons.Do you think any damage was done to it.

 

[Atilathehun99]

I just bought a 1979 721 bobcat .I checked the hydraulic fluid and it was pouting out.I drained out about 6 gallons.Do you think any damage was done to it.

Sounds like you might have water. If a 721 is set up like a 722 the HF reservoir is the chain cases. Check for a drain plug at the bottom of each behind the back wheels. Crack them and see if water drains out. If it does the smart thing to do is a complete HF change. Should be 10W-40.

 

[hatchet]

Sounds like you might have water. If a 721 is set up like a 722 the HF reservoir is the chain cases. Check for a drain plug at the bottom of each behind the back wheels. Crack them and see if water drains out. If it does the smart thing to do is a complete HF change. Should be 10W-40.

The plugs to check the fluid are to the rt of that circle cover.i open the top one and it was overfilled so i drained it until it was even with the hole.

 

[Atilathehun99]

The plugs to check the fluid are to the rt of that circle cover.i open the top one and it was overfilled so i drained it until it was even with the hole.

Those are the high/low check plugs. Look for the chain case drain plugs at the rear in back of the rear tires. The rubber might cause it to be hard to see these plugs. When I drained my 722 I took the wheels off for easy access.

 

[hatchet]

If their was water wouldnt the oil look milky

 

[Atilathehun99]

If their was water wouldnt the oil look milky

It's an open system so there will always be some condensation making it look milky. Doesn't take very much H2O to do that.

 

[Gearclash]

It's an open system so there will always be some condensation making it look milky. Doesn't take very much H2O to do that.

I have never ever seen a properly functioning hydraulic system get enough condensation water in it to turn the oil whitish. Tractors, skid steers, etc.

 

[Atilathehun99]

I have never ever seen a properly functioning hydraulic system get enough condensation water in it to turn the oil whitish. Tractors, skid steers, etc.

As you know the HF on 72x series is contained in the chaincases. Each side has a open vent to atmosphere. That presents a source of water vapor and the large area of steel inside of the chaincases presents the opportunity for water vapor to condense and contaminate the HF. This at least is how I always figured H2O entered my HF as I couldn't find or foresee another way for it to accumulate.

 

[Gearclash]

As you know the HF on 72x series is contained in the chaincases. Each side has a open vent to atmosphere. That presents a source of water vapor and the large area of steel inside of the chaincases presents the opportunity for water vapor to condense and contaminate the HF. This at least is how I always figured H2O entered my HF as I couldn't find or foresee another way for it to accumulate.

Guarantee you the water is coming either from rain making its way in or power washing. The Case 1835Bs I like so much are terribly prone to water intrusion to the chain cases. It is not from condensation alone. The problem on those is the chain case covers that are located on the top of the chain case, on flat steel, and never did seal well from the factory.

Tractor transmission housings have acres of heavy cast iron that is not submerged in oil, all of which will sweat like crazy on the outside during weather changes of cold to warm and humid and yet they never show moisture in the hydraulic oil inside them. Steel reservoir cases don't sweat anything like the cast iron housings do.

I have seen several examples recently of water contamination that was almost certainly from a powerwasher blast that went past a seal. There was no other way for water to get in the gear case and there was very little free air space inside the case for moisture to condense.