[rsp420]

I have a JD 420. I recently had the trans fluid changed at the dealer. When I got it home I noticed the fluid was not showing up in the site glass. Thus, I figured that the dealer did not fill the fluid up enough and I proceeded to add about 3/4 of a quart of hydro fluid. As I was filling, I checked the site glass several times and still saw no fluid in the site glass. Then, all of a sudden fluid started leaking all over the driveway - probably a half quart came out. I could not determine where the fluid was coming out of. I have researched old posts, and it seems that there may be a breather hole somewhere where the trans fluid is discharged if it gets overfilled, but I could not find any definitive posts on this topic. Can anyone verify the existence of the breather hole and tell me where the hole is? Also, if my trans fluid is full, why would it not be showing in the site glass?

Thank you!

 

[shadetree]

The fluid is clear. The tube is clear. You can't tell the difference. Either change the tube to something you can see through. Or dye the fluid so you can see it.

 

[chuckv]

Scott,

The Deere low-viscosity fluid branded Hy-Gard is relatively clear, and if there is not a meniscus (air/fluid boundary edge) visible in the site tube it could be either that the fluid is below OR ABOVE the short section of glass tube. The vent is in the fitting where the upper section of the site tube hose connects back into the transmission housing. Here is the operator's manual instruction on how to check level in the transmission:

This illustration is from an early 318 manual and mentions Type F fluid which is dyed red and a bit easier to see in the tube... It is very easy to overfill, so add in small increments.

Chuck

 

[rsp420]

Great, thank you for your help. Would it be correct then that if the fluid was over filled that any excess would have been discharged out through the vent hole?

 

[chuckv]

NO, you still have to drain enough out to get the level back to the middle of the sight tube...

It is quite possible that the dealer is not very familiar with the older models and put in the amount of fluid in the manual without keeping close tabs on the sight tube -- a previously filled transmission does not drain completely (particularly if it is not at operating temperature...) so the replacement fluid will not require the "manual specified quantity" due to the retained fluid on the parts internal to the hydro itself.

Chuck

 

[knottyrope]

the top port where the site tube connects was plugged on my 420 so the sight glass would never show correct amount

 

[bo2009]

Scott,
Search 'elbow' or 'elbow fitting'. JD has a dye you can add to the Hy-Gard, MT3668. Bobo

 

[jd2854020]

Scott,
A little more infor on the dye mentioned above.

JD Hydro Fluid dye
Part Details
Part Number: MT3668
Part Price: 3.91 USD
Description: FLUID, HYDRAULIC OIL DYE

Deere uses a red dye in the hydraulic oil to help identify oil leaks on the assembly line.
Deere has adopted a part number for the red dye, MT3668. This is available in a 12 mil. bottle which will treat 5 gallons of hydraulic oil. Readily available from your local dealer. Reference DTAC solution 67928.

 

[coalminer16]

Just used that oil on my 332 this weekend. And put in my fathers 430 as well.

 

[newguy]

I just picked up a bottle of dye. I talked to 3 different deere dealers about the oil dye. None of then knew of it. One dealer said that the only way to get dyed oil is to get it from the deere assembly line.

 

[coalminer16]

I ordered online. I rarely deal much with dealers other then the bulk things like the oil/other heavy fluids. The hours and issues with some parts and distance now to them just makes online easier. And many offer free shipping depending on order size. The dye can be bought. Try greenfarmparts.com.

 

[KB]

My dealer didn't know what I ordered either when I got dye. they were surprised it was availible

 

[shadetree]

Why doesn't Deere just dye it GREEN? Then you could tell it from Type F and still see it.

 

[trapperjohn]

I am colorblind and had trouble seeing the fluid in the tube. I painted the tube bracket white and use Type F fluid and no more problems.

 

[sreynolds]

Is this different from the 400 tractor? They have a fill point and a plastic sight tube. With he 400 hydro unit one simply threads in a set of 90° fittings and fill to overflowing at that fitting. Run engine and cycle the hydraulics and top off. can't get that wrong.

 

[KB]

Scott,

Ariens are the same way for filling, and it is great. they do lack a site tube though

 

[sreynolds]

yeah? I think that is pretty cool. Real tough to get that wrong, unless you don't top it off after running the unit to fill the filter etc. I can see that the fluid level is tough to see if you don't replace that plastic tube. They discolor and turn yellow. Same color as the hy-gard oil.

 

[bo2009]

Evidently different: 400 vs. 420.
1st photo is from the TM 1590 - 316, 318 & 420 L&G tractors.

People in the know informed me that the white plastic elbow fitting shown in the photos above has (or should have) a small vent hole. If the hydrostatic transmission is overfilled with fluid, then when warm after operating, it will expand per se & excess fluid will leak\spew from there. It's worth a look-see. Bobo

 

[420glh]

Like others have said, the plastic fitting has that hole in it. I found it the same way you did, Scott. I added a little trans fluid for contrast.