1975 350 Dozer leak

[C.miller]

So I'm new to the dozer realm. I just bought a 75 straight 350 dozer. I'm currently learning about all the reverser problems that come with it. My problem is after running for 10-15 mins it starts leaking hydraulic oil out of a pin hole on bottom of the bellhouse. From what I've read there should be a pin in that hole also but there is not. I've heard that there may be a seal on the reverser that could be causing this leak? It didn't leak right away when started but was after I cycled the 6 way blade through all its range of motion. Again I just purchased it and runs great but just noticed this leak yesterday. I have checked both dipsticks on the floor and both read full. This tells me in my mind either the leak just started, the pervious owner new about it and refilled all the fluids before I purchased, or the leak is hydraulic fluid from running the blade?
Thanks for any help.

[Jim B]

The weep hole originally would have had a loose-fitting cotter pin in it. The pin was loose so it could giggle around and keep the hole open. If there is oil coming out that hole it is either engine oil or oil from the reverser. Reverser oil is separate from the hydraulic oil. Engine oil is generally darker colored, and the reverser oil should look about like new oil, if it is clean.

[C.miller]

Definitely not engine oil. Its clean and not dark. Would that mean seals on the reverser are bad? Any idea if I should not run it till fixed.

Thanks again.

[LeonardL]

Your leak is most likely the reverser pump seal that seals the input shaft. It can also be an o-ring that seals the pump itself and it is located behind the pump in a groove milled into the pump housing.

The down side to this is it could indicate a deeper issue. But we will hope for your sake that it is just a bad seal. Either way I wouldn't operate it until you have it fixed. This is reverser fluid that you're loosing and you don't have a lot of fluid to loose. There is only about two and a half gallons of fluid in a reverser. So any leak at all would be a bad leak.

[C.miller]

Do you by any chance know the part number for these seals? Trying to get my hands on a manual right now.

[LeonardL]

You can find your parts at (https://partscatalog.deere.com/jdrc/) The O-ring or "Washer" as they call it is ( T19147 ) and the Oil seal is ( AT29365 ) You need to find out exactly what you own. Try to find your serial number and then match your manuals to that series of machine. I highly recommend you getting a Tech manual as well. Again you will need to know what machine you have. That being a 350 straight, B,C or D. A 350 Straight and a 350B or both pretty similar but they are different than a C or D.

[Jim B]

Leonard is correct, you need to find out just what your crawler is, then get the proper manuals for it. 1970 was the last build year of straight 350s, so you can't have a 1975, straight 350. 1975 was the end of the 350B series and the start of the 350C series, there are some major differences in a straight 350 and a 350C. If you look on the "John Deere crawler FAQ's" Board here the second post down is a listing of the 350 model series by year and serial numbers for those years. About 17 posts down Stan Disbrow posted the John Deere manual numbers for the various models. Lavoy has (or can get) manuals in his store, which provides this site for our use.

[C.miller]

Went back over to the dozer today. Does anyone know where a serial number may be stamped in somewhere. No ID plates on the machine. Did talk to the previous owner, he is unsure what it is because he believed it was a 75 straight 350, but he is positive it has dry clutches which I believe narrows it down to 2?
As for the leak I cycled the reverser in forward and reverse while idling and nothing change but when I idled it up the oil leak intensified. I'm certain it is not motor oil though. It is still coming out weep hole right infront of where reverser and transmission mount together. Haven't run it enough to see any level change on any dipsticks.
Thanks again.

[LeonardL]

Okay so I thought you said it was leaking from the weep hole in the belling housing behind the engine. Now you say it is the weep hole between the reverser and the transmission. So either way you are still looking at either a reverser leak or a transmission leak. The only way to fix it is to pull it apart.

As for a stamped serial number?? You might look on the top flange of the frame which is hard to get to. I've seen them stamped on the left side where you enter the machine. You will need to remove the step first to see the frame. There is no way to know if your machine has this or not. Some had it but most didn't. You may also find one stamped in the transmission housing. The problem with the transmission location is if this thing has ever been swapped around with another 350 it will cause the number, if there at all to be wrong.

One way to determine if yours is a "Straight" or a "B" is to locate where your reverser shifter is located. Most Straight 350's were located on the left side of the dash panel. Most 350B's are located on the left side next to your left arm rest on the battery box. Some very late Straight 350's also had the shifter in the same place as the 350Bs. Another indication is if it has power steering. A straight 350 will have a pump and reservoir mounted to the front of the engine. A 350B is powered by the reversers residual hydraulic pressure. So there won't be a pump on the front of the motor.

The problem with all of this is the age of these old crawlers. They have been hacked and swapped around to the point that it is hard to say what you have without someone who knows these machines to look at it. A straight 350 and a 350B are very interchangeable as is a 350C and a 350D.

So bottom line here is you may have to take it apart and remove the old seals as gently as you can so you can get the numbers directly off of the seals. That way you can interchange them. Or you can always go by shaft diameter and bore size to match a seal up.

[Jim B]

Leonard has good info for you. Another clue to narrowing it down is where the serial number tag was located. Look for two 1/8" holes about 3 inches apart in the locations shown in these pictures. This info comes from the JD parts catalogs. Of course, there is always the chance parts have been swapped over the years, but maybe not these panels as much as driveline components.

[C.miller]

Just verified it has a powerstering pump and reservoir on front of the engine. The reverser is located on the left arm rest and the ID plate was located by right foot and not the battery box. Would you all agree that I'm safe to assume it's a late model (70) straight 350?

For the leak because it's coming from the rear weep hole are there gasket/ o rings between the reverser and transmission? I'm think about running it for hour or so and check levels periodically to see what drops because both reverser and transmission are reading full.

[Lavoy]

Straights never had a reverser shifter on the armrest, always the dash.
Lavoy

[C.miller]

Also no leaking at a low idle,checked today leak starts at about 1500 rpm and will go away when idled back down.

[C.miller]

Thanks lavoy, do you know if any b's had a powerstering pump and reservoir?

[LeonardL]

I hope Lavoy doesn't mind me taking this last question but it is possible. So,Yes it is possible you have a 350B with the older pump with a reservoir being on it. Yet another scenario I ran into is Deere kept the pump but did away with the reservoir. They supplied the pump with lube pressure oil from the reverser. Once it passed through the steering system it had a return line that fed the fluid back to the reverser.

So again with the way these things have been changed on the assembly line at Deere and then the owners swapping components around it's anyones guess what you have. Most of the 350B's I was ever around had the power assist steering getting the needed hydraulics from the reverser.

That being said, when Deere made a serial number break or a series break sometimes things got a little crazy on the line when they assembled these things. We had a 350B delivered to us once that had a 350B decal one side and 350 on the other. There were other nuances that made this crawler a bit weird as well. One was it had a track frame on one side that had the sprocket guard and the other side did not. The serial number however clearly made it a "B" series crawler.

The upside to all of this is you have two very similar machines. Especially the very late Straights and the very early 350Bs. So it isn't as hopeless as it may seem.

There is no gasket between the two housings. There are o-rings that seal the bearing quills and then shims that set end play on the given shafts that also serve as gaskets... sort of but not really! I know that makes no sense but they do seal a bit.

You will have an output shaft seal on the reverser and an input shaft seal on the transmission. In your given situation I would take those seals and have them crossed to make sure you get the right ones.

You are going to have to pull this thing apart to get to these seals. Given the depth and the labor involved I would not do this without going through the reverser while you have it out. In my experience, every time I had one come in with a seal leaking they all led to having bad bearings that caused the seals to fail. The input shaft on the early reversers especially are very prone to do this. If it was me I would want to make darn sure that reverser is okay before I stuck it back in the machine.