[jsoluna]

Just thought I'd document a rare case of hydro problem that I witnessed at the shop today.

Unit: 2010 Cub Cadet 2554
Hours: 90.5
Complaint: customer stated lack of forward/reverse power when unit is cold.

Now, this Cub hadn't had a fluid or filter change at 90 hours, so when he brought it in, we immediately jumped on him for not servicing it, so that at the very least it would look good if Cub/MTD had any warranty concerns. We changed fluid/filter (fluid looked like liquid sin), and that didn't change a thing.

Took it out for a test run, and noticed that a whining noise was starting to develop, but then dissipated after it warmed up - and with the noise gone, hydro operation was back to normal. Hmmm....

Came back after Christmas and the head tech tore right into it. Took fender/seat pan off to access the hydro. He was prepared to take off the charge pump assembly to check the o-ring seal when he found the culprit.

The suction tube fitting was loose. That's it. There were no indications of fluid leaking anywhere, the hydro was dry as a bone on the outside, but the suction tube fitting at the hydro had backed off enough to suck air in until it got warm, at which point it would re-seal itself and presto! Hydro would act normally.

Tightened the fitting and on she went, happy as can be....

 

[mowergene]

That makes a LOT of sense! Air does not hydrolic fluid make.

 

[thunderbirl]

Would there have been a lot of foam in the reservoir while it was sucking wind? Would that be a clue worth looking for?

 

[mowergene]

You say fluid looked like liquid sin........black?? I've never had a CC tranny fluid get dark. Perhaps it was suckin' air AND dirt.

 

[jsoluna]

Yes, when I heard the sound the hydro made, I thought it sounded like a power steering pump that hadn't been bled yet so I checked the dipstick and sure enough, it was foamy. So yes, that was the dead ringer that air was indeed the problem. Weird thing was that when it first came in, it wasn't making the noise at all, and while the fluid looked gross (description below), it wasn't foamy.

Yes, the fluid looked horrible. It was a dark grey/graphite color from all the metal accumulated in the break-in period. If these things don't get changed by about 20 hours they start looking like that. Cub's recommended 10 hr filter change is no joke. I'd change fluid and filter if it were mine.

 

[thunderbirl]

An alternative hypothesis for the color...

The entrainment of air (oxygen!) into hot petroleum products would turn them black and may cause them to get more viscous.

Running for 90 hours with air just can't be good!

Thanks for the photo and the tip. I'll be checking that fitting when I pull off (and repaint) the fender pan this spring.

 

[jsoluna]

Thanks for the replies guys. This is the main reason I wanted to work at a dealership - to gain the knowledge and be able to pass it on to the community

The color of the fluid was not really atypical for 90hours of use - there's a lot of the GTs around here, and at least half of the owners have to be beat over the head to do any maintenance at all. First is blades, then engine, and finally the hydro. They are real stout pumps, though, I'll give em that. I've seen plenty with high hours and crappy looking fluid that are as quiet and strong as they were on day one.

 

[savageactor7]

Thanks for the heads up jsoluna, and I really like the pic with the typed description too.

 

[jsoluna]

No problem Hope it helps someone down the line. Just goes to show that sometimes it boils down to something very simple.

 

[MTD snow plow]

Thanks for the replies guys. This is the main reason I wanted to work at a dealership - to gain the knowledge and be able to pass it on to the community

The color of the fluid was not really atypical for 90hours of use - there's a lot of the GTs around here, and at least half of the owners have to be beat over the head to do any maintenance at all. First is blades, then engine, and finally the hydro. They are real stout pumps, though, I'll give em that. I've seen plenty with high hours and crappy looking fluid that are as quiet and strong as they were on day one.

Sounds like alot of people around here. I was BSing with the local cub shop and they said that almost nobody changes it. In my cub the fluid was nasty and it stinks real bad.

 

[jsoluna]

When it comes down to it, people just aren't into preventative maintenance as much anymore. They buy something, use it for a few years, and then trade in. What's the point in servicing something and throwing money at it if in the end you're not going to hold on to it for more than a few years? In regards to the hydro - part of the problem is that the Cub Drive System Fluid Plus is outrageous in price. For those who aren't inclined to do the research and find out what spec the fluid is in order to search for an alternative, it's easier just to not even bother with it.

 

[john_bud]

In regards to the hydro - part of the problem is that the Cub Drive System Fluid Plus is outrageous in price. For those who aren't inclined to do the research and find out what spec the fluid is in order to search for an alternative, it's easier just to not even bother with it.

Sooooo, what is the alternative fluid that is less expensive that that liquid gold the dealer sells?

 

[jsoluna]

Hydro-Gear specifies 20-50 heavy duty engine oil, or synthetic equivalent for the BDU-10 hydro in the 2000/2500 Series. Several have used Shell Rotella 15w-40 or Rotella 5w-40 synthetic. Use factory filter, it's bout the same price as aftermarket.

The Cub Cadet Drive System Fluid Plus is a Shell Spec-TTF-SB 10w-40 synthetic oil.

 

[67Truckin]

How often does it need changed on a 2186?

 

[67Truckin]

What if every time I check the hydro oil, it is clean and clear? I've put over 100 more hours on it since I bought it. Should I still change it or did the previous owner do it after the break-in period and its good to go now?

 

[mowergene]

I am a true NUT when it comes to changing oil......25 - 50 Hours on the air cooled engines.......1000 - 1500 on my car & truck. On hydro fluid, I'm very lax. My best buddy had a small engine repair shop and acreage of his own. He NEVER changed hydro fluid and managed to get by alright. On my 2146 I changed at 50, 100, 200 and 1600 hours (note the gap at the end). Over the ten years I had the machine, it stayed perfectly clean! The machine was stored inside (heated and air conditioned) and when run during the mowing season, it was run for goodly periods of time so that if any condensation were present, it probably burned off. I'll probably treat the 2550 similarly.
I drained the hydro on my JD LX178 the other day and it was probably the first change it ever got (it's filterless), and it's 17 years old! It's a "tuff torq" and runs on 10-30 motor oil. My plan is to run it hard for a couple hours next summer and drain it again. It holds less than 4 quarts. It came out pretty black on that first change!

 

[jsoluna]

Break in period is the hardest on the hydros. There's a lot of mating surfaces that get polished in that period of time. After that, it's typical for the fluid to stay relatively clean unless there's a problem.

 

[thunderbirl]

I've been reading this thread with great interest. In 2008, I bought a used 3225 which had seal problems and came to the realization that one of the very important aspects of a hydro oil change was to remove the metal shards that result from polishing. These shards can cut up the rubber seals on the bearing blocks and cause leaks.

Here's a link to my discussion of the logic and basis for that realization.

In that thread - and today - I support the concept that the fluid change following the intial break in period is the most critical and that later changes are not likely to be so important.

However, as a full-on research scientist, my view is that a plausible hypothesis like this one predicting that later fluid changes may not be as important as early ones is still only a hypothesis. It may be true, but should (and can!) be tested.

So I took this all one step further... and installed a drain plug with a magnet on it to see how much metal was being thrown after 10 years of use and polishing.

I don't have any pictures. When I changed the filter and fluid last year, the plug had a nice clump of very fine shards on it. Now this was about a year after installing the plug (following an annual oil/filter change) and about three years after rebuilding the transaxle (so it was really pretty clean at that point). Thus, it's possible that the amount that I saw was either one year's worth of shards (if all the past shards were removed with the oil change) or three years worth if they weren't. I don't know which this was, but I'll be doing another change this year and that "should" be one year of what the magnet can gather.

The amount I saw was no where near the two teaspoons full of metal that I removed from the first eight years of use (I don't know if the fluid/filter was changed by the previous owner, but I suspect that it was not.). I can't be 100% sure that all the shards are on the magnet, but it seems like a pretty good assumption - and more work to test than I want to contribute at this point!

So, this tells me that there is a reduced amount of polishing going on after some initial "break-in" period. This would seem to support the importance of that first change. I just can't tell you what that period is.

However, my observations support there are some shards continuing to be formed in these systems after the first few years. Since my major goal is to avoid shards - to avoid having to change those bearing blocks - I'm going to continue to change my oil and filter on an annual basis.

I'm also going to go out on a limb here and suggest that the magnetic drain plug is a good tool for removing these shards. Please keep in mind that I'm changing the filter on an annual basis, but the filter is clearly not getting all the shards. Some are settling down in the bottom of the transaxle.

The magnetic plug was a M14-1,50 Magnetic by Oil-Tite. It's a Dorman part 65216 and I bought it at Autozone. Here's a link to the product:
Dorman 65216 at Amazon

 

[jsoluna]

Awesome information!

When I tore open the 3205 rearend, it was horrible. I had catastrophic failure to account for some of it, but the fine metal particulate was also common to what I've seen in other rearends. Operators manual states to change filter at 100 and fluid and filter at 150....but there's no way I'd wait 100 hours before filter. Even at 10 hours, the fluid turns from clear/light amber to a light silver in color.

These HydroGear pumps can take a lot of abuse, I'm convinced. Both the BDU-10 and the BDU-21. There's lot of units out there with horribly contaminated fluid that have whisper-quiet, super strong hydros.

I'll be investing on that magnetic drain plug for sure. Thanks for the link!

 

[mowergene]

You've got to love magnets! I've started putting them on my filters..........I wonder how effective that is???? Ever since the invention of the alnico (aluminum, nickel & cobalt) magnets, we've got gobs of gauss in a small containment! If we can keep just one shard of crud out of circulation, we've done something! That one shard may be the one that causes the purchase of a "for sale" sign.