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Is it better to have the hydros hot or cold to drain the fluid & change filters.

7394 said:

Is it better to have the hydros hot or cold to drain the fluid & change filters.

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The service manual doesn’t specify either way. I don’t think it matters. Once you remove the filters, the oil spills out easily.

Thanks MParr- very true.

Warm oil just drains faster and more completely. There will still be areas that will not drain.

OK Thanks, I have "Internal expansion tanks" on my HG 2800s' & I drained a precisely measured 118 oz combined total of OE 20w-50. (yes I'm that anal to measure the drained oil),.

Research states about 2 quarts per unit on my application.

You got to remember the oil filters contains some oil.

Also you need the Hydro-Gear dual barb fitting, part number 55752 to refill the oil. Or at least it makes it easier.

StarTech said:

You got to remember the oil filters contains some oil.

Also you need the Hydro-Gear dual barb fitting, part number 55752 to refill the oil. Or at least it makes it easier.

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Absolutely, & that accounts for the extra missing.

Yes I have that blk dual barb fitting, or you can just open the very top fill caps & side oil level caps.
I used the fitting. I filled them to full level. .. Letting it sit a couple nights, & then check levels & start purge process.

OK, so in continuing. I have added new (oe) H/G oil filters & using the dual barb fitting added fluid. I could only get
all but 16 ounces in of a gallon on 2 internal expansion 2800 units. Let it sit 2 days. Checked fluid level & it was to level.

Then with dump valves released, started it, rear off the ground & at low rpms run the sticks slowly 6 times times. Stopped it, leveled it on blocks & then checked fluid levels, they both wanted more fluid in each.

Now I am about 10 oz short of 1 gal total. & will have more purging to keep doing maybe tomorrow.

Any advice would be greatly appreciated.. These are my 1st serviceable hydros.

Look at the serial numbers on your particular units. Now, go the the Hydro-Gear service manual and look at the chart on page 9.

Yes Thank You- (EDITED Correction) I had a link saved, but it was from 2011. So I deleted that, & saved your new link from April 2023. Thank You Sir.

https://www.hydro-gear.com/wp-content/uploads/2023/05/BLN-52441_P25-23.pdf

Info certainly has changed..

7394 said:

Yes Thank You- I have the link saved, & have verified my serial numbers as internal expansion unit. It seems my pertinent info & chart begins on page 10 & onward..

Says fluid capacity is 77.23 fl oz for each unit only. But this is also for External expansion units, even tho it is clear it lists this as for the hydro unit alone.

I only drained a total of 118 fl oz outta both combined. Not counting oil filters soaked media.

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How did you drain the units? Drain plug, turning them upside down, extraction with a pump? This process should not take that long, nor does it have to be exact. Go through purging process with bypass open and closed, add oil until full.

Tiger Small Engine said:

How did you drain the units? Drain plug, turning them upside down, extraction with a pump? This process should not take that long, nor does it have to be exact. Go through purging process with bypass open and closed, add oil until full.

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The ZT 2800s have spin on filters. The fluid drains through the filter mounts.

7394 said:

Yes Thank You- I have the link saved, & have verified my serial numbers as internal expansion unit. It seems my pertinent info & chart begins on page 10 & onward..

Says fluid capacity is 77.23 fl oz for each unit only. But this is also for External expansion units, even tho it is clear it lists this as for the hydro unit alone.

I only drained a total of 118 fl oz outta both combined. Not counting oil filters soaked media.

Click to expand...

Okay. Check the level when cold. If there is a slight trickle of oil from the check plug hole, you are good. I do know that the ZT3100s with expansion tanks take about 73oz. per side. That is a little shy of 5 quarts total.

For future reference, draining when hot will not only drain faster, but any debris in the system will flow out while it is still in suspension. That's been the preference.

MParr said:

Look at the serial numbers on your particular units. Now, go the the Hydro-Gear service manual and look at the chart on page 9.

https://www.hydro-gear.com/wp-content/uploads/2023/05/BLN-52441_P25-23.pdf

Click to expand...

Opened your link. Different that what I have saved. Says my unit designated by a "T" in serial number holds 56.6 oz per side.

Just be aware when external tanks are used the drained fluid amounts can vary as even different length hoses will change the total amount drained. As long as you get very to the spec'd amount you will be okay. It is even note is the service manual about the hoses.

I got engines here that spec 64 oz of oil that can require an additional 8 oz at times. Nothing is ever 100% accurate as there are variables. Even different filters can hold varying amounts of oil depending how they are made.

Yes agreed. mine are Internal expansion tanks. Hydro-Gear Tech said mine should take approx 63, so I am very close between both numbers. Just need time to do good purging..

https://www.hydro-gear.com/wp-content/uploads/2023/05/BLN-52441_P25-23.pdf

MParr- your link is from April 2023. The one I was so set on was from 2011. Doh !

No wonder I couldn't see the current info you directed me to.

Thank You for the current link & directing me to page 9. I deleted my obsolete link, & saved your new one. So much has changed.

I can report, I have my Liberty hydros purged, & it is now so quiet, smooth & Very responsive.
I tested it for a 1/2 hour then parked it, & looked her over. I still have to put filter guards back on.

I used Amsoil 20w-50 Hydro fluid, & Hydro Gear # 52114 oil filters.

Thanks to all who contributed to my thread.. Much appreciated.

MParr said:

Okay. Check the level when cold. If there is a slight trickle of oil from the check plug hole, you are good. I do know that the ZT3100s with expansion tanks take about 73oz. per side. That is a little shy of 5 quarts total.

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OK, after the purge & working it for a solid 1/2 hour. Been parked & now good & cold. Checked hydro fluid levels & both are slightly below the level on side fill level ports. Only like maybe 1/8" under...

So, should I top them off again, then call it good.. I just want to be sure.

The little pistons get air in then and in place of being pumped out so oil can replace the air, it simply compresses and decompressed.
This is why you purge with the wheels off the ground so there is no resistance in the motor pistons
You do it at low speeds to reduce the oil frothing
Some times they purge really easy and some times it takes forever and a day

Just make sure the region around the fill pot is VERY clean
do the final addition and go mow

MParr said:

The ZT 2800s have spin on filters. The fluid drains through the filter mounts.

Click to expand...

Yep, good point. I forgot.

7394 said:

OK, after the purge & working it for a solid 1/2 hour. Been parked & now good & cold. Checked hydro fluid levels & both are slightly below the level on side fill level ports. Only like maybe 1/8" under...

So, should I top them off, then call it good.. I just want to be sure.

Click to expand...

You want a slight trickle from the inside inspection/fill port. In other words, level with the bottom of the hole.

Bert- I almost surgically cleaned my units.
MParr- 10-4 on that.

Ok, After 1st purge attempt, rear off the ground. Did that. Then put back down / level & left overnight.

Checked fluid levels next day & found to be low, took about 2 - 2.5 fl oz per side.

This 2nd time purging after adding top off oil previously mentioned, both units were lil weird noisy in free wheel mode (both sides, pump valves released) stroked 6 times slowly, shut off let sit 10 minutes, engaged the pumps valves & started it off the ground, it was quiet, still stroked the sticks 6 times slowly.

Then ran it a solid 1/2 hour all around the property, all seemed good, quiet & responsive.

Now fluid levels are a very slight bit low again. Temp overnight in my shop was 60* F. Just fyi.
Hot weather would likely read a bit higher. IDK to add just enough to hit bottom of side fill port ?

OK, I can report my Liberty 48" is running so smooth, nimble & actually quieter than when I bought it new.

I only have 50 hours on my machine, but it was recommended by my Dealer to service these Hydro-gear 2800's early @ around 50-ish hours, to get off to a good start..

Because my Hydros have internal expansion tanks, it takes a bit less fluid (56.6 fl oz) each before purging) than external units.(Thanks MParr for latest current H/G link). So I went with Full synthetic 20w50 to help try & keep my hydros a bit cooler.

After final purging then overnight sitting, I ended up adding a few more drops of oil for a total of 59.6 fl oz in each unit to the bottom of side fill ports.

After that, is moving onto just everything else, where's my wax can ?