Blowout on HST filter

[jovialjeeper]

In June, I bought a used (~60hrs) Case DX40 from a dealer. Fired her up last night to move some snow around and within about 2 min. hydraulic oil started blowing past the seal on the spin on HST filter. Somehow it was blinded, but I'm trying to determine what to do next. Is this an indication of a larger problem? What should I look for? By the way, I happened to have an automotive filter that would fit so I could limp her back to the garage. She just turned over 100 hrs.

[DANOCHEESE]

Call your delaer they have a cold weather filter. THis happened to a few others.

[jinman]

The Case and New Holland HSTs all have a filter problem in cold weather. There is a special filter that is made for cold operation. It is Part #SBA240500980. There has been extensive discussion of this in the New Holland forums and your Case or New Holland dealer should be able to get you that filter if they don't have one in stock. The problem is that the HST filter can have as much as 300 psi pressure. The normal seal can't hold that pressure and blows out. The heavy duty filter should solve your problem. This only applies to the HST filter. No other filter has this issue.

[jovialjeeper]

Thanks for the responses. I searched and read the other posts.

Just an FYI. The part number is SBA340500980.

[john_bud]

Nearly all HST transmissions seem to put the filter after the pre-charge pump. Normal operations are about 200 psi in the filter. Cold temperatures make the fluid thicker and the system pressure relief is not able to bleed off fluid fast enough to reduce pressure and you get a leak.

Kubota went thru at least 3 iterations of this filter. The current one has a machined base and co$ts lots of money. (I blew out 2 incarnations that I know of).

Solutions are;

Use the stouter filters AND maybe some of the following

Warm the tractor up longer with the clutch dogged down. 5 minutes for every 5 degrees below 15 or 20F. That will disconnect the HST pre-charge pump so it won't push any fluid until it warms up.

Use thinner fluid. Kubota recommends SUDT. I think NH has a similar fluid (5w30 vs straight 30w)

Park the tractor in a heated shop (yeah - right!) or use a magnetic heater on the transmission. (Marginal at best)

[jinman]

Originally Posted by john_bud

Warm the tractor up longer with the clutch dogged down. 5 minutes for every 5 degrees below 15 or 20F. That will disconnect the HST pre-charge pump so it won't push any fluid until it warms up.

JB, good advice. However, the DX40 has no clutch and the charge pump runs anytime the engine is running. There is no way to warm up the engine and not also run the charge pump. However, if the engine warms at low rpm, that will probably be the best for keeping the pressures low. It will just take a long time to warm up 10 gallons of cold hydraulic oil in the reservoir.

[RickB]

Originally Posted by jinman

JB, good advice. However, the DX40 has no clutch and the charge pump runs anytime the engine is running. There is no way to warm up the engine and not also run the charge pump. However, if the engine warms at low rpm, that will probably be the best for keeping the pressures low. It will just take a long time to warm up 10 gallons of cold hydraulic oil in the reservoir.

That's good advise, but unfortunately many, many filters have failed at cold start low idle while the operator is warming the tractor properly with good intentions. Best bet right now is to cough up the big bucks for the xxxx990 filter. NH ic currently changing the regular filter ONCE AGAIN; we have not recieved the new number to stock yet. Time will tell if this new filter can be used in colder climates.

[john_bud]

Originally Posted by jinman

JB, good advice. However, the DX40 has no clutch and the charge pump runs anytime the engine is running. There is no way to warm up the engine and not also run the charge pump. However, if the engine warms at low rpm, that will probably be the best for keeping the pressures low. It will just take a long time to warm up 10 gallons of cold hydraulic oil in the reservoir.

I do tend to forget about machines that have (in my opinion) cheaped out and don't have a clutch.

My left foot would get mightly uppity with nothing to do while tractoring!

jb

[jinman]

Originally Posted by john_bud

I do tend to forget about machines that have (in my opinion) cheaped out and don't have a clutch.

My left foot would get mightly uppity with nothing to do while tractoring!

jb

Well, those of us with these type tractors are actually pretty thankful we never have to worry with any clutch "stuff" as others do. Our left foot stays "happy" with the brake pedals and differential braking while our right foot stays "happy" with the HST pedals. The "uppity" part is the guy in the seat feeling so smug because he has such a good layout. That smugness comes to an end quickly though when the HST filter blows and the left foot gets "baptised" in hydraulic fluid. Too bad that NH didn't use the money they saved on the clutch to build a system with a bullet proof HST filter.

Disclaimer: This message comes to you from a guy who has never had a problem with his own HST filter, but just identifies with the frustration of those who have.

[john_bud]

Well, Kubota did finally fix the issue as it has not leaked on me in 2 winters with the newest style filter. And, the kubota has never pee'ed on my foot! That would be just too disgraceful for words. It has however, pee'ed in the shop, on the lawn and on my trailer. When you gotta go, you gotta go - but never on my foot!

Now, if I understand your clutch free tractor, it is spinning the HST pre-charge pump when starting the engine? That wouldn't go over real well here at -30F. Stuff gets mighty thick and chewy at those temps. Probably not a concern at all down in the warmth.

jb