Cub cadet 7205 Hydrostatic drive surging - sharing my problem AND fix!

[Ed in Maine]

Single owner of this 7205 since new in 2000, 550hrs now, no issues aside from glow plugs but that is another story with tons of threads.

I mowed with a 5' finish for about 4hrs then parked tractor, next day it was surging bad and eventually would not move after 5min of running. Then it was like the selector was still in neutral, no sounds or anything from hydro when in gear.

Dealer was VERY helpful over the phone and I mentioned I used a napa gold hyrdostatic filter they crossed me to. After scolding me some, I left with an oem filter (black one that goes right under seat). Still nothing. They said I am pulling air in from somewhere and air bound. I went through all fittings going to the charge pump of the hydro (side of hydro drive, then following line up to cooler and back) and was surprised that I could easily get a 1/4 turn on each.

Like magic, the tractor surged forward some finally! I kept rocking it back and forth but there was obviously still air in the system. I parked it nose down on a steep hill and lost all hydro, so I parked it nose up and worked it back and forth some. She came out of it perfectly and hyrdo is running smooth, quiet, and stronger than ever.

I think the after market filter had too much pressure drop on the return and actually created the air leak. Just sharing my experience and recommending you buy the right oem filter! MA-19632558 is PN for my 7205, and likely same for the Mahindra 2015.

Throughout the whole deal, I was looking closely at the EX3200.... hard to get rid of this nice little tractor but the EX3200 looks rugged.

 

[Ed in Maine]

Well, I thought I was onto something but it is taking in air again. I was hoping that tightening the bajo fittings fixed it but now I am going to try replacing the washer/seals on the suction side of the charge pump. I hope the charge pump is not bad, it was running real strong just yesterday before the air got back in.

Open to any and all suggestions, but I think I am getting close!

 

[Yandaddy1110]

My B2400 is in need of a new charge pump. The tractors hydro tranny works fine while cold till the fluid warms up. Then it whines and surges. Some times it wont work at all when the fluid is hot. Also sometimes when going down hill it will break away and roll. No back pressure in the hydro, classic bad charge pump symptoms.

I bought this tractor with a bad hydro. I did rebuild it, but left the charge pump alone. I also had to replace the hydraulic pump.

 

[Ed in Maine]

Same signs here, it will roll down hill and get away from you a bit and then kick back in. I just took out the hex plug in the middle just to see if there was any pressure and there was only a few bubbles.

Anyone have a service manual that they can scan a few pages in on how to remove the charge pump? Tractor needs to come apart, just not sure if there are any settings or tensions when putting it back together?

 

[Yandaddy1110]

There are several Cub Cadet 7205 service manuals on CD on Ebay.

 

[OldMachinist]

http://www.mymowerparts.com/pdf/Cub-Cadet-Service-and-Repair-Manuals/Cub-Cadet-7000-Series-Compact-Service-Repair-Manual.pdf

 

[gtrippleb]

I'm not sure if this is the same manual as what OldMachinist linked to or not, but it is a shop manual that covers the following Cub Cadet Models. It's broken down into the different sections also in case you're on a slow internet connection.

Shop Manual

7192
7193
7194
7195

7200
7205
7232
7233
7234
7235
7260
7265
7272
7273
7274
7275

7300
7305

 

[Ed in Maine]

OldMachinist hit the nail on the head, this is the exact manual I need! Thanks a ton.

I am going to tear into this thing and see what I can make of it. But now that I know what each of the valves in the hyrdo do, I am going to inspect each of them. I also have some of the rubber coated washer on order that go on each side of the 16mm banjo bolts. One had a slight score on it from the line being torqued when tightening hyrdostatic filter. Still can't rule out an air leak.

Fired tractor up again just for heck of it. Surged forward a few ft then stopped, would not go forward or backward again after that.

 

[Yandaddy1110]

Sounds to me like the charge pump is not getting any fluid. Like it just fed what ever fluid was sitting inside of it out to the hydro and then quit because no more fluid is being pumped to the charge pump.
Or whatever drives the charge pump isnt being driven anymore for whatever reason.

Hydros can be a big headache, sometimes I wish i just had a simple clutch and gears.

 

[Ed in Maine]

Yes, that is exactly how it sounds. It is taking in air or a high pressure valve is stuck open?

 

[Ed in Maine]

I just go through putting a gauge on the charge pump test port (supposed to be 60 - 85psi) and read 0 psi, needle did not even bounce. We could still get tractor to surge once or twice forward by pumping the main clutch.

I removed the Forward and Reverse high pressure valves on the sides of the hyrdo and inspected for a sticking valve but they looked fine.

I removed and inspected the short steel line that goes from the hydraulic filter to the charge pump. That is the only suction of the charge pump and one side is an O ring press fit, but it looked fine. I did replace and reinstall the o ring, still no pressure.

So next step is tractor split. Going to drain fluid and remove lines/linkages and prepare to split this weekend. Any and all feedback is appreciated!

 

[Ed in Maine]

A few pics of what I'm up to.

 

[Ed in Maine]

Split the tractor and I obviously have a busted gear in the charge pump. New one is on order.

 

[Ed in Maine]

New charge pump arrived and I had it installed and put back together by myself in about 2hrs. Putting the sheet metal, seat, etc, took another hr or so. Obviously not too tough of a job. Chain fall and over head I-Beam came in handy.

This thing is back to NEW with the new charge pump. It was obviously worn out some several years back. I can climb up steep hill in H range, which I have not been able to do for a few years. Overall cost was just under $700 for all parts (pump, seals, fluid, filter), but I am very glad I did the repair. Makes me want to keep tractor for another 13 yrs.

 

[glinkh]

Where can I get the parts reasonable priced for my charging pump

 

[Ed in Maine]

Cheapest is to match your model up with the equivalent and order through mahindra. Will save you a hundred bucks. There are also other cub parts dealers on the web that have oem parts for discounted rates. I went that route due to free shipping. Someone out of Ohio, can't recall who.

To follow up, tractor is running like new again.

 

[Graderpete]

Good information here, thanks! I just got done installing a new charge pump, but the machine still doesn't want to move for me. Did you have to do anything special to get the air bled out of the system? Any other tips?

TIA

 

[Bob_Bainbridge]

Good information here, thanks! I just got done installing a new charge pump, but the machine still doesn't want to move for me. Did you have to do anything special to get the air bled out of the system? Any other tips?

TIA

FYI - You may not have noticed but the post you are replying to is over 3 years old. Just in case you don't get an answer that's probably the reason.
Bob B.

 

[Graderpete]

FYI - You may not have noticed but the post you are replying to is over 3 years old. Just in case you don't get an answer that's probably the reason.
Bob B.

Yes I did notice....Hoping for the best :anyone: lol

Thanks!

 

[redmondson]

Hi Ed, just saw your post! How did it work out? I have owned a 7205 since new (17 yrs) and with no problems. My friend borrowed it it came back loosing power in the HYDROSTACTIC till it would move at a craw. I changed the filters and oil.......Not the will not move..the other pumps work loader/3pt/PS. The dealer cannot get parts and will not work on it...The pump shows zero pressure. I guy that does hyrdo is going to work it in...It's been there a month. He said could not find a service manual..I got him on the 772-4207 rev 6.95 he will now work it in. Did you get yours fixed? Did it last? Did you find any videos or step by step to break apart and repair?
I would be grateful for any help...I have been without a tractor for 2 months.
thanks,
Rick from INDIANA