Oil & Fuel JD 4200 tranmission site glass yuk

navmed · May 31, 2015

I cannot tell if I have my transmission fluid levels are to standard by looking at this site glass (located near the PTO - rear of tractor) on my JD 4200. The glass always has a small 'bubble' at the very top of the glass which would make me believe it is 'full'. I know it uses (and loses) some of the oil through the transmission and hydraulics but the level never goes down. Can't tell if it was full or not...so today put in 4 gallons of transmission/hydraulic fluid and the bubble remained. Still does not give me an accurate fluid level. Hope someone out there understands this and can help. Love my JD but want to take care of it but am concerned I am over...or under...filling the transmission/hydraulics reservoir. Thank you.

RoyJackson · May 31, 2015

I had a 4400 until recently...and I know exactly what you wrote about. That sight glass was a pretty useless method for checking fluid levels. I wish I had a suggestion for you, but I don't. I do know I wish the 4400 had had a dipstick.
However, the good news is, unless you see leakage (drops or puddling after the tractor is parked) or the bottom of the case exhibits signs of leakage, you probably don't have a problem.

Egon · May 31, 2015

Drain and keep the oil. Might prove the sight glass. Sometimes parking on an angle will make a change.

TCSavage · May 31, 2015

I use JD hydraulic dye in the hydro which makes it visible in the sight gauge.

pmsmechanic · May 31, 2015

The bubble in the top of the sight glass will never go away. You could fill the transmission until the oil runs out the fill hole and it won't make any difference as it's the way the sight glass is designed. If you have access to an owners manual it says to park on a level surface and the oil level should be in the center of the sight glass. I find it's an easy way to check levels. Just a glance and you know everything is where it should be.

roush9799 · May 31, 2015

I got my 2520 back from getting a rear engine seal replaced. There wasn't any oil in the sight glass, I didn't know if they drained the hydro system or not when they split the machine. I filled it up, it sat overnight and the oil was gone. I filled it again and it started to come in the glass. I let it set over lunch. Came back out, no change, I poured a bit more in it and it ran out the fill hole. Needless to say I drained out about a gallon. Probably gonna have to change it out and measure as it goes in.