Bobcat T770 Hydraulic double flush

[shawnseveras]

long story short i have a t770 that has metal shavings in the hydraulic fluid. i will be doing a double flush on the entire hydraulic system. ill be using this guide to do so http://info.texasfinaldrive.com/shop-talk-blog/how-to-flush-your-hydraulic-system . so im purchasing all of the filters and will be getting all of the oil and perform the double flush soon. hopefully it will solve my problem. the system has already had both drive motors replaced recently so im hoping those didnt go bad again but we will find out soon. well if anyone disagrees im open to suggestions. but it seems that they made a few changes to the filter setup to the fan motor filter. ie the charge filter on the maintenance book isnt on the bobcat website for my specific serial number because they replaced it with a regular old metal white filter.

 

[Michael Kast]

how did it go?
I have been told this is what is done to large industrial machinery when they change the oil viscosity to prevent mixing of viscosities. I am in the process of doing this to my motor oil. Next is the hydraulics, but first I need to stop all leaks. I think my cheat will be to change the hydraulic oil ASAP, then work on leaks, then change fluid and filter a second time once it is proven the leaks are repaired. I haven't seen any signs of mechanical failure other than leaks so far.
I am attempting to revitalize a poorly maintained Takeuchi track loader 140. I could have built an adobe hut from the oil infused clay I shoveled out of the belly pans. I couldn't even begin to know what was leaking until it was cleaned. It was a crap shoot as to whether it was worth the low price I payed. It seems to have plenty of life in it but surely more will be revealed. The deeper I get into this thing the better I am feeling about it. That is the good news.
I have a question on this topic of flushing an oil system while I am hijacking this thread. Is it unwise to use a "detergent" Such as Seafoam or something like that on the first oil change when it seems very clear the oil has not been changed or properly maintained in way too long??

 

[TVA]

It says: “drain existing fluid only when it is reached operating temperature”? Really?!?!

So you have system full of shavings!
The return filter probably plugged up because of that and bypass valve is open.
In this condition you just recirculate the crap probably killing both gear pumps!

If you want to do this - first thing you have to do is drain existing fluid from the tank with crap already in it, or at least replace fresh return filter on so bypass wouldn’t open!

 

[shawnseveras]

how did it go?
I have been told this is what is done to large industrial machinery when they change the oil viscosity to prevent mixing of viscosities. I am in the process of doing this to my motor oil. Next is the hydraulics, but first I need to stop all leaks. I think my cheat will be to change the hydraulic oil ASAP, then work on leaks, then change fluid and filter a second time once it is proven the leaks are repaired. I haven't seen any signs of mechanical failure other than leaks so far.
I am attempting to revitalize a poorly maintained Takeuchi track loader 140. I could have built an adobe hut from the oil infused clay I shoveled out of the belly pans. I couldn't even begin to know what was leaking until it was cleaned. It was a crap shoot as to whether it was worth the low price I payed. It seems to have plenty of life in it but surely more will be revealed. The deeper I get into this thing the better I am feeling about it. That is the good news.
I have a question on this topic of flushing an oil system while I am hijacking this thread. Is it unwise to use a "detergent" Such as Seafoam or something like that on the first oil change when it seems very clear the oil has not been changed or properly maintained in way too long??

well... the double flush went like this, drained fluid and then refilled ran for 30 seconds. then drained fluid changed filters(hydro-static,hydraulic) 2 different filters btw. and then refilled with fluid and ran for another 30 seconds or until the heat level raised to the oil viscosity ambient temperature. then i drained and refilled again then followed it up with another filter change out. after that i refilled and fired it up and have been running it since then! no problems what so ever. keep in mind the viscosity has to match the normal temperature ranges for the environment that it will operate in, ie if it is 100 Fahrenheit outside per normal then you will want some thicker fluid.

fyi, come to find out that the last maintenance done on the machine was a replacement of both drive motors that move the tracks. there was a manufacturer fault in the motor and that is what caused the shavings to appear in the first place. customer didn't flush the attachment so when it was reattached the shavings from the incident made its way full circle and back into the filter. lessons were learned and all is ok......

 

[shawnseveras]

It says: “drain existing fluid only when it is reached operating temperature”? Really?!?!

So you have system full of shavings!
The return filter probably plugged up because of that and bypass valve is open.
In this condition you just recirculate the crap probably killing both gear pumps!

If you want to do this - first thing you have to do is drain existing fluid from the tank with crap already in it, or at least replace fresh return filter on so bypass wouldn’t open!

that's what i did and she is in the clear. we have since added 100 hours to the machine with no fault codes nor any signs of shavings in the fluid. she is also performing better when it comes to hydraulic power!