Where did my transmission fluid go?

[Mike_S]

With a year old JD4400HST that has been very dependable, I changed the transmision/hydraulic fluid, changed the filter and cleaned the suction screen which was very clean (didn't have a third of a cup of metal filings on it like my previous 4400). 50 hours after the tranny fluid change and using the loader to clean up ice storm damage to trees, the sight glass showed the transmission fluid to be at the top of the site glass as usual when the tractor was parked in its basement garage. i check the sight glass before and after each lengthy tractor use. After a snow, and clearing a mile of rural road twice, I removed the rear blade and FEL and observed that the tranny fluid was in the same spot at the top of the sight glass when parked in the garage. THEN I towed my daughter on her sled for an hour around my small acreage and I used road gear for maximum speed. The ground is uneven and in places I bounced out of the seat momentarily. When I parked the tractor in its garage, the tranny fluid was at the bottom of the sight glass showing it to be low. The filler cap was still tight and a VERY close inspection beneath the tractor did not show any leaks or places where it might have leaked. The dealer's service dept. had no clue and neither do I. It just could not have beamed up--anyone with ideas as to where it went? Mike S.

 

[Mike_S]

Addendum: I had to add a half gallon to top off the transmission/hydraulic fluid. I drove it three miles and then checked the sight glass to find that it was still full. Another close inspection beneath the tractor revealed no wet areas or drips. I remembered that the top connection to the transmission cooler had leaked slightly when the tractor was new so removed the front cowling and both sides, but found no leakage there either. The only change made in the tractor was the replacement of the hydraulic control valve for the 3 pt. about 50 hours ago. Surely this is not a one of a kind Twilight Zone kind of issue. Mike S.

 

[kubmech]

Mike, do you think it's possible you had the 3ph all the way up or the loader in a different position than the last time you checked it? If your 3ph is up, lower it, set the loader bucket flat on the ground and see if the level goes up.

 

[Mike_S]

Good thinking, but in this case the tractor is always parked with the 3 pt. up and the FEL down with all pressure released. Mike S.

 

[Harv]

<font color=blue>3 pt. up and the FEL down with all pressure released.</font color=blue>

Don't you have to let the 3 pt. down before you can release all the pressure?

 

[Mike_S]

Harv--never entered my mind since I have always been in the habit of leaving the arms up after one of them jumped out and hit me in the chin one time when I left them in the lowered position. But in the case of my original posting, I am consistent in the way that I leave the tractor when it is parked in its garage, thus, any change in the level of tranny fluid in the sight glass would be evident. Mike S.

 

[Egon]

Mike:

Could the gauge glass have been air locked/blocked and the bouncing released it? Or could it have a check valve/ball of some sort in it that was stuck?

Egon

 

[Mike_S]

Egon--having replaced the sight glass in my last 4400, I understand its design and doubt would a bubble have blocked it. Mowing season is quickly approaching and then time will tell if this was a fluke. Mike S.

 

[GaryK]

when replacing the filter, did you fill it with fluid before putting it on the tractor? if not it could have been airbound and given you a false reading until it filled up with fluid.