TC40A Hydraulics Hissing

[mundamanu]

Ever since I did my 50 hour service (70 hours ago), I have noticed that the hydraulics hiss. I feel like they didn't hiss before I performed the service, but I can't be sure. The only thing I did with the hydraulics was change the hydraulic filter. The seal is good and the oil level is fine.

I hear the hissing when I slowly raise or lower the bucket, and especially when I turn the steering wheel. It is a quiet hiss that goes away as soon as you release the hydraulic controls or return the steering wheel to normal position. I don't hear the hissing when I raise or lower the three point hitch.

Is this normal? Does it need to be taken care of?

Thanks,
Bob

p.s. -- Sorry. I thought I was in the Owning/Operating forum...

[jinman]

Bob, the steering and the main hydraulics run off of two completely isolated and different systems. If you changed the main filter only, there is no way it could have an effect on the power steering.

This is not to say that they both could not be hissing. It just means that you didn't cause it and you just probably have a little post first-time jitters.

[Soundguy]

My only thought could be that he changed out oil in both systems.. perhaps putting a thicker oil back in.

How bout' it Bob? you cahnge the oil in both systems or no?

Otherwise.. what Jinman said.

Soundguy

[jinman]

Originally Posted by Soundguy

My only thought could be that he changed out oil in both systems.. perhaps putting a thicker oil back in.

How bout' it Bob? you cahnge the oil in both systems or no?

Otherwise.. what Jinman said.

Soundguy

Chris, in Bob's post he said,

"The only thing I did with the hydraulics was change the hydraulic filter."

The 50 hr service only calls for changing the hydraulic filter, not the fluid. That's what I think Bob did.

[mundamanu]

Originally Posted by jinman

Chris, in Bob's post he said,

"The only thing I did with the hydraulics was change the hydraulic filter."

The 50 hr service only calls for changing the hydraulic filter, not the fluid. That's what I think Bob did.

Yep, Jim is right. I only changed the filter. I did also check the power steering oil level and that is fine too.

So, is the hiss not something I need to worry about? Like I said, I feel like it started after the 50-hr service, but I can't be sure. Immediately after I did the service, I was extra attentive to the sound of the tractor just in case I screwed anything up, because as Jim rightly pointed out, I had the first-time jitters, so it might have been happening before and I just didn't notice.

One other thing that I noticed that I forgot about earlier is that since the 50-hr service, if I have the bucket angled down when I lower it to the ground , it curls to level as it goes down (whether I push the control just down or all the way to float), whereas before it used to maintain whatever angle I had it set at. Now, once the front edge of the bucket hits the ground and it starts to curl up to level, I can push the angle control once and it will hold the angle, but like I said, if I don't push it, it automatically curls to level. It is possible here too that this didn't only start happening after the service. However, in this case, I am pretty sure that it did.

[Soundguy]

My bad.. I missed that part!

Ignore the bearded guy and carry on!!

(wink)

Soundguy

[jinman]

Originally Posted by mundamanu

One other thing that I noticed that I forgot about earlier is that since the 50-hr service, if I have the bucket angled down when I lower it to the ground , it curls to level as it goes down (whether I push the control just down or all the way to float), whereas before it used to maintain whatever angle I had it set at. Now, once the front edge of the bucket hits the ground and it starts to curl up to level, I can push the angle control once and it will hold the angle, but like I said, if I don't push it, it automatically curls to level.

Bob, that curl issue would be a strange "beast" if it had anything to do with a filter change. With the bucket hanging downward, but not all the way to dump, there will be some upwards slop once the linkage gets broken in and is not too tight. Also, there will be some movement inside the cylinders due to the change in pressure from hanging weight to upwards pressure from the weight of the bucket. I think you are experiencing a normal action. Not being able to see it is limiting my judgement, but it does sound normal. The next time you are at your dealer, you might ask him to let you try that on a new tractor on his lot to compare what it does. That would be the best comparison in my opinion.

The humming sound could be coming from the engine or even be a vibration that occurs when the engine is under load. Since the main hydraulic and power steering pumps are separate, I think you are hearing something from the slight loading of the engine. It could even be something in the exhaust due to a slightly increased flow as the engine loads. The hydraulic pumps are gear driven, so there is no belt to slip or other reason for you to hear something different except the slight engine loading from one of the hydraulic pumps. You could also just be hearing fluid run through the system. The fluid for the steering runs through the valving in the steering column and the hydraulic flow in the lines under the right side of your operator's platform. You could hear some hissing, but it would be coming from slightly different locations for the steering or the main hydraulic pump to the loader or 3PH.