Is flushing hydrailic oil, damaging or should it be a top up only?

[Sutton]

I know all manuals on the machines specify to replace the hydraulic oil periodically. Most at around a 1000hrs.
However is flush the system damaging?
Here is what i have experienced
I reasently bought a used ASV. Before buying it, i had the oppertunity to work the machine all day on a job.
At day end i had a good look over the machine as i new i might be buying the machine. On oil leaks i found only 2 of the rams leaking oil(everything else was dry).
After the purchase i had the machine at an ASV expert for some repairs on the undercarrage, it was ponted out to me the badly conatamined hydrailic oil. They then flushed the system several times. (See the picture of oil samples as provided to me). This all seemed like a good thing.
However 1st job out, after the simi-rebuild.
Now a lot more oil leaks
4x of the rams was o/hauled in the rebuild, the remainding 2 rams started leaking. That means all 6 rams started leaking.
On the bottom transmission showing leaks
One of the hydraulic drive motors started leaking badly(the ASV specialised suspecting o'rings in the motor as the cause of oil leak).
I started with only 2 rams as oil leak, now multiple leaks. The machine now have knocking sounds if operated on a bank (the leaking side of the track)
What could have caused this?
Was the flushing of hyfraulic oil the cause?
On some motor vehicles i know the differentials oil will be specified to be topped up only, as complete drainage or flushing will cause failures in the unit.
Is this what is happening to my machine?

 

[Hotrod1830]

As far as the fluid samples are concerned, I am not sure what I am looking at. For the hydro oil you should only have 2 samples. New vs old(yours). I see 4 samples.
Hydraulic oil, just like engine oil , transmission fluid or gear oil needs to be changed due to the wear on the fluid itself. Moisture, dirt and wear particles(metal) and time reduce the effectiveness of the fluid/lubricant. flushing the fluid, providing the correct fluid was used will not harm your machine, or any machine. From what I remember when I worked on one, is that ASV's are very particular as to the fluid used. mainly just operation though. Never heard of one springing a leak. We used fluid from the dealer.

That being said, it is possible that your machine was already on its way to a failure, and you are seeing the failure now, regardless of what was done to it. Possibly the new fluid created more pressure in the pumps and the worn seals announced their presence.

Changing the fluids will not FIX a machine that is already in the process of failing. It is simply maintenance. If the prior owner didnt do it, you are seeing the result and get to pay for the result.

 

[mrbb]

I know of no OEM that doesn't want as full a drain as possible when replacing fluids
the whole point of removing the OLD, is ,as time passes and heat cycles happen, the oils break doe, and or can collect metals and or other things
thus when draining a system, the goal is always to remove as much of the old fluid as possible before adding new fluid

when dealing with say a differential, and leaving bottom of old fluid in it, thats almost like asking for issue's IMO, as the bad things will lay where things puddle up and DON"T drain
so there the more vital places you want to remove if possible!
now keep in mind that NEW fluid will contain cleaning agents and be able to flow better
so if you had OLD thicker oil that was starting to break down and become more like a gel, than a fluid
well it would also, possibly be keeping some, things from leaking,as the contaminates in the oil are acting like a plug, or just being thicker from age

ever see oil that was NOT changed in a few yrs, how thick it gets!? that thicker oil and what ever also is in it can work like sealer and prevent things from leaking
But once you get new fluid in , its not the new fluid caused damage, its just most likely the new fluid, with being thinner and the cleaning agents, have now mad what ever was plugged up preventing leaks, to now leak!
the damages were already done, just were plunged with old fluid and ???
this is why when replacing fluids, you should replace filters as well, so the what ever that got loose will get caught in the filter!
and if fluids are very dirty, they should be flushed several times and new filters each time, to help caught the contaminates! and a fluid change after clean, should happen IMO< before a regular time frame, to ensure things are clean!
oil/fluids is still cheaper than rebuilds and down time! IMO!

NOW< there is always a chance that MIXING two different types of fluids can have a reaction, and I mean two different brands of LIKE fluids
its mostly a rare deal, but not all fluids are made up of the same things and as such, some times there can be a reaction to mixing them!
this is why I always use the same fluids, brand make weights, it leaves one less possible issue to worry about
and LAST, I have heard some folks have Leaks after switching from Dino oils, to Synthetic oils, but again, most times, its not the new fluid,it was damages seals already and the new fluid just cleaned things and now leaking!
every test I ever seen to try and prove syn oil can cause leaks, has been a bust, and not the Syn oils being at fault!

 

[Jyuma1]

What hydraulic fluid is recommended by the manufacturer versus what hydraulic fluid was used to replace?

I'd start there.

 

[oiu789]

Did they use some kind of flushing fluid or just the correct hyd oil for your machine?

 

[Sutton]

Thanks for the response.

I know the oil should be changed periodically.

This is just a mystery to me.

I did the effort to test the machine a full day before the purchase.

Bought it and then all the failures.

Logically i'm only thinking of what we have done to the machine and whether any of these are reasons for the failures.
Reason why i brought up the many hydraulic oil change theory

It's just mind blowing, how is it possible?

Now even worse, back from the mechanic again. $13 000 later making it a better machine. Done one job with it and it now has hydraulic drive motor problems.

The mechanic is telling me that one of the hydraulic drive motors has failed and needs to be replaced.

Is it just my bad luck? Or is this a ASV thing?

Really starting to dislike asv.


My old bobcat has more than double the hours on it and in all the years I have this machine, I don't think I have repaired so many things on it.

 

[Sutton]

Jyuma1, they only used the correct oil with every change. It wasnt mentioned to me that they have used any type of flushing agent

 

[Fabricator]

it was ponted out to me the badly conatamined hydrailic oil.

As others have noted, the damage was likely done before you purchased it. The leaks were basically there, just clogged up by the contaminated fluid. The fresh fluid got things flowing - both properly and through the leaks. The contaminated fluid is also likely to damage pumps and motors and such.

Checking the fluids for condition is one of the first things I'd have done before purchase. Unfortunately, many people will do a quick change of all fluids before sale - whether they've been doing proper (or any) maintenance previously or not, so that isn't always a reliable indication.

 

[mrbb]

I think its a combo here, of, maybe lack of PM's being done in the past, and age, , like parts with same amount of hours or use on them tend to fail about the same time , I know its frustrating to have one thing go after another, but everything is a wear and tear game, and , the secret IMO to long life of parts, is being cared for often with new fluids, fail to replace fluids often, and things wear faster IMO
as they say, its a big part of how long a machine lasts or not, IMO< how it was cared for, and not just how it was used
all owners are not the same when it comes to doing PM"S
and as for costs, this is also why a lot of owners have learned to fix things themselves,a s going to a dealer for things adds up $$$$$ really fast
I know we cann cannot do repairs, but just saying, dealers can turn smaller things into costly repairs at times

 

[Sutton]

Yip Seems like damages must have been present before buying the machine.

The previous owner or owners got me good. OR is it just ASV?

Added failures to date now already repaired
-Failed right drive motor
-Water pump failure
-Crank seal replacement, had to do this twice due to crankshaft being pitted(Oil leaks)
-Drive coupling between engine and hydraulic pump failed(Engine had to come out)
-Fuel leaks from tank (badly , machine had to be pulled from site)
-Electrical failures

This machine didnt complete any full day job without a break down

Now more than $30 000 spend on repairs in 3-4 months time period

Sorry to those ASV fans but ASV sucks, BIG TIME