Forst ST6 Hydraulic oil leak

[Thesnarlingbadger]

Are you certain there is water in the oil? Hydraulic oil can foam up and come out of the breather (top of tank, sometimes the filler cap itself) if it is sucking air in from somewhere. It will be on the suction side - check all the connections and seals on any filters between the pump and the hydraulic oil tank. The pressure side will squirt oil out if there is a leak, so is easy to find.

 

 

I ran it earlier with the housing open and there was no sign of any oil squirting out of anywhere other than the filler cap. Will try again in the morning but I'm pretty sure it's water getting in and not air. The fluid that came out was like milk and there was a hell of a lot of it.

I've checked over all the seals and they look fine.

If I have to bleed the system and change the pump and filter then so be it but I need to make sure that I get all the water out. Do you know if I just let the whole lot drain for a day, would it be clear or do I need to get the air compressor out and blow the through the hoses?

As I said to begin with I'm a little over my head with this but want to sort it (maybe a little for self satisfaction).

Thanks for the replys

 

 

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[monkeybusiness]

It won't leak any oil out if the leak is on the suction side of the pump. A leaking seal will let air into the hydraulic system, and you won't be able to see it happening (but it will make the oil foam up when it returns to the tank, and then expand out of the breather after a while). I doubt very much that it is water in the oil as it wouldn't necessarily expand when running and then leak out of the breather (unless it was a massive amount of water, which I doubt). I would definitely not change any components until you know what the issue is - if it is water in the oil how is it getting in? If it is air in the oil,how is it getting in? Either way, fix that issue first and then pressure test the system to check for damaged components. Maybe find a local hydraulic firm to give it a quick once over - I guarantee from what you are posting that it will save you money in the long run.

[Thesnarlingbadger]

It won't leak any oil out if the leak is on the suction side of the pump. A leaking seal will let air into the hydraulic system, and you won't be able to see it happening (but it will make the oil foam up when it returns to the tank, and then expand out of the breather after a while). I doubt very much that it is water in the oil as it wouldn't necessarily expand when running and then leak out of the breather (unless it was a massive amount of water, which I doubt). I would definitely not change any components until you know what the issue is - if it is water in the oil how is it getting in? If it is air in the oil,how is it getting in? Either way, fix that issue first and then pressure test the system to check for damaged components. Maybe find a local hydraulic firm to give it a quick once over - I guarantee from what you are posting that it will save you money in the long run.

 

cheers for this reply. I will try and drop it in to a local hydraulic firm tomorrow morning. there is one round the corner from me. I personally can't see how any water has got in, let alone a large amount. Would pictures help to determine weather or not it is water or air in the system for you guys? if so I'll get a picture, or is it really that similar that you can't tell the difference?

[jeanesy]

Its not under warranty, I got it second hand 6 months or so back and it's a 2013 model. It's been a cracking machine otherwise.

The machine runs ok but yesterday I noticed the leak (not to bad) then today I started her up to see if the oil was that milky colour and it pissed out of the filler cap after 20 seconds of running idle, only had it running 30 seconds and there was at least 3 litres of oil/water that pored out.

I've got no idea how the water got in and have checked the hoses and seals and they all look fine. So it's either the pump like redwood said or possible the filler cap.

What I don't want to do is get it all running again and find out the water got in some place else as I only have a week to get it sorted.

 

 

 

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Didn't they give you a years warranty when you bought the machine? I bought a 2013 machine off them and had a years warranty.

[Thesnarlingbadger]

Didn't they give you a years warranty when you bought the machine? I bought a 2013 machine off them and had a years warranty.

 

 

It wasn't from them. It was a privet buyer

 

 

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[monkeybusiness]

If there is lots of water in the oil the oil will look milky/white in the oil level sight glass. It takes a long time to separate out so should still be noticably milky a few days after the last use.

[Thesnarlingbadger]

Well I have taken it in to Listers this morning. They think it is air in the system, and more than likely from one of the pumps. They are going to pressure test them on Monday and hopefully find the issue.

I think it's probably best to leave this one to the professionals as I might end up cocking the chipper up more.

Hopefully I can get the chipper back by Friday for this job.

Thanks a lot for the replies on this as I had it down to water in the system after what I'd been told.

Thanks again I really appreciate it people :-).

 

 

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[monkeybusiness]

Ace - hopefully won't be too expensive a fix!

[openspaceman]

Well I have taken it in to Listers this morning. They think it is air in the system, and more than likely from one of the pumps. They are going to pressure test them on Monday and hopefully find the issue.

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I thought the st6 only had one pump, an 11cc/rev gear pump with an outrigger bearing, if the outrigger bearing fails it puts a radial stress on the pump and they cannot stand that. If so it could suck air.

[Thesnarlingbadger]

I thought the st6 only had one pump, an 11cc/rev gear pump with an outrigger bearing, if the outrigger bearing fails it puts a radial stress on the pump and they cannot stand that. If so it could suck air.

 

 

Apparently there are pumps on eash roller as well, I'm guessing these are just small pumps.

I know of the main one below the filler but the guy at listers said that there are pumps on the rollers as well. Hi may have just thought because other machines have pumps on the rollers mine would or maybe there are. I didn't check as I figured he had more of an idea that I do.

 

 

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