550 trans rebuild

[adamshuss]

Well I rebuilt my transmission (clutch packs and seals) but it still has some hesitation shifting between ranges and speeds. The transmission is definitely better than it was, no longer creeps in neutral, but still has a siftdelay. The only noticeable problem I saw when rebuilding were the steels in the forward clutch, they were warped about 3/4". I noticed after the rebuild I can hear a whine when in gear, my pressures were low before the rebuild and have not changed much. I am planning on replacing the pump but wanted a second opinion...thanks

[Tigerhaze]

Hi Adam-

Were the warped steels replaced during your rebuild? That would be a problem if they were put back in.

[adamshuss]

I replaced all discs and sealing rings on all clutch packs.

[digitup2]

If it is whining then look for gear sets not totally lining up correctly.I have had that problem before and needed a shim to set things straight.there are spots on the clutch packs they aren't lining up.Look carefully.Digitup.

[adamshuss]

I described the noise wrong, it is a vibration in the lines rather than a whining. Sounds like it is sucking air somewhere. Anyways, replaced the pump, rebuilt all clutches, replaced all o-rings, pulled control valve and selector valve and cleaned all spools / bores and still only have 130 psi in Reverse and 130 in F3. Any more ideas?

[digitup2]

You had mentioned that this machine hasn't seen much work for a while .Put a few hours on it doing some decent pushing don't beat it too hard but work it some what for 20 hours and see if the shift speed and hesitation straightens up get back to us it will clean up it's act if it gets the cobwebs out .Digitup.

[JD430C]

If you havent done it yet clean the filter screen in the transmission. My 550 was making a similar noise yours is, filter screen was plugged.

Andrew

[adamshuss]

The filter screen was previously checked and found to be clean. I think that it is sucking air somewhere and from what I can gather it could only be from the screen through the suction tube and into the pump, unless I am missing some other area that could be under vacuum. I forgot to mention if I take the dozer on a hill (front of dozer pointing down) and try to reverse, often times it will start to move and then completely disengage the clutches. I noticed the oil is quite milky, I was under the assumption of moisture but with the noise in the transmission line coupled with the other symptoms I think it is foaming the oil. Can anyone think of an ingenious test to find a leak from the suction tube to the pump...without pulling the motor and converter housing? Has anyone ever had trouble with cracked suction tubes or bad o rings on the suction tube?

[digitup2]

that oil should not foam so that should be a red flag try to flush that system and run clean oil never milkie .Digitup.

[JD430C]

Dont have the manual handy, but I believe it said to add a couple extra gallons if its believed to be sucking air from the suction screen or a bad o ring. Will check it this weekend.

Andrew

[adamshuss]

yes I do have the manual and did add 2 extra gallons. I did not know if that would cover the front o ring or not, either way that leads to my next question... could anything bad come from adding a bunch of oil to the transmission to completely cover the suction tube and o rings?

[adamshuss]

Well I dropped the oil again and it is milky. What I don't understand is there is no oil in the radiator and I am assuming oil pressure through the cooler is greater than the radiator pressure. I have changed the oil 3 or 4 times and it has been milky everytime. I rebuilt the transmission last year so I know it was empty when I refilled. Where am I getting the milky oil?

[digitup2]

cooler may be leaking so watch that I have had a 550 do that.Digitup.

[adamshuss]

If the cooler were leaking, wouldn't I see oil in the radiator as well, since the trans pressure is higher than the rad pressure during running condition? I was assuming on shutdown I could get water into the trans due to lack of trans pressure but during running the opposite would be true. I am planning on pressure testing the cooler tomorrow regardless. Another question I had; Is the steering clutch housing the same as the transmission housing? I thought it was but noticed in the manual they talk of 28 qt of oil for each steering clutch compartment, is the 13.5 gal sufficient for the entire housing or do I need to add the 13.5 gal and the 56 qt?

[adamshuss]

I have everything apart again. I tested the suction line with air and did get a little air leaking around the front o ring. If I test the each clutch with air while out of the machine will any of the air get around the clutch piston seals or should it be completely contained? I figured I would do this to ensure proper sealing before reassembly, is this a good way to test or is there some other way?