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Transmission Fluid Leaking

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West T

08-01-2011 10:10:42

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I have a question that would appear very simple but I'm curious if anyone has any insight as to what might have happened. I finally got around to changing the transmission fluid on my TO30 this past winter. I used what you fine gentlemen on this sight recommended (I think it was 5W-30, I'd have to look back through the posts to be sure) and all was well. But since it has gotten warmer it started leaking out of the foremost drain plug and the PTO. I previoulsy had no issues with the tractor leaking. I have tightened the drain plug as best as I can get it (or without over torquing it anyway). It is not a substanial amount of oil leaking but it did not leak before. I'm sure it is because the oil is thinner than what was previously in it but still doesn't seem right. Thanks in advance.


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West T

08-02-2011 10:31:13

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 Re: Transmission Fluid Leaking in reply to West T, 08-01-2011 10:10:42  
Thanks guys. I mentioned 5W-30 but if John recommended 15W-30 then that's what is in there as I value the input from this site. I put in 6 gallons as the instruction manual indicated. I didn't however fill it slowly as described in this thread. It kept taking the oil so I put the whole 6 gallons in. Sounds like I will replace the gasket on the drain plug next spring and hope that I haven't wrecked the seal on the PTO. I am curious as to the mention of the weap hole on the front of the trans. What is the purpose of this and if the oil is coming from there is that bad?

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John (UK)

08-03-2011 10:59:22

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 Re: Transmission Fluid Leaking in reply to West T, 08-02-2011 10:31:13  
You wont damage the seal through filling it all at once, it is just if the seal is worn then the oil will leak into the Clutch housing. But do check the oil level by removing the bottom screw out of one of the round side covers and allow any surplus to run out. Ignore any suggestions of running with only half the amount of oil in the transmission as this can cause overheating of the oil. The original oil (GL1) is outdated and the oil now recommended is a multi-grade 15W/30 which is a better lubricant and does not get thick and heavy when it is cold. As someone said said "ask an old fergy repairman what oil to use", you can"t get much older than me, I have been working on these tractors when they were still in production here in the UK and they finished in 1956. Multi-grade is a better oil for all year around. Weep holes are to allow any oil out of places that it shouldn"t be in. Sometimes when an oil seal or gaskets leak, you need to get rid of it before it does damage and that is what the weep hole is for. Every so often check both the cotter pins that they still turn easily and then the vibration will turn them as the tractor is running, not as the grass contacts it as someone suggested, some tractors do not go in long grass or even any grass so it always has to work.Just turn them a few times and they should be OK.If you have any problems with it or any questions ,just email

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08-02-2011 10:55:57

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 Re: Transmission Fluid Leaking in reply to West T, 08-02-2011 10:31:13  
guess they planned on the trans leaking oil and did not want it to get on the clutch plate so they installed a bit of insurance, a drain hole.

my trans TO=35 has leaked oil out of the drain hole for years, but no clutch problems as the weep hole has a upside down carter key installed.

As the tractor travels through weeds and grass the key turns and keeps the hole open.
Note to file: if you ever get the tractor stuck and mud gets into the drain hole and stops it up and if your trans does leak, oil will build up in the reservoir and will get on the clutch pad.

i just keep the trans filled to about the halfway full mark (lift arms must be in the down position when you check the fluid).

you need the maximum amount of fluid in the reservoir and not stored in the lift cylinder when checking the fluid level.

Again, ask some older fergy repairman about those brass, bronze bushings in the older Fergy transmissions and what oil is best lube for them. gl-1

New tractors do not have those type bushings bearings in there transmissions.

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08-02-2011 04:15:22

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 Re: Transmission Fluid Leaking in reply to West T, 08-01-2011 10:10:42  
why 5w30 or whatever oil,
I do not believe that is what fergy recommended in your manual.

you have bronze bearings in the transmission and that is what the old gl-1 or mineral oil was made to protect. its not the lift system you worry about its the transmission bearings.

you may need a new gasket for the drain plug, surface may have gotten nicked
I have the same large drain plug on the motor oil pan on my TO-35 and i have had to get a new gasket for it at napa, stopped the leaking.

if oil is running out of the pto, maybe you overfilled the system.

look at your manuel, i just do not believe it calls for for 5w30 (did not have that type oil back then) my old tractor runs good and lift system has been working great for 50+ years on gl-1 mineral oil, they sell it at napa for a reasonable price.

just my two cents!

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Richard McClain

08-01-2011 13:03:55

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 Re: Transmission Fluid Leaking in reply to West T, 08-01-2011 10:10:42  
Shawn, same thing happened to me when I changed trans/hyd fluid. I believe the accepted replacement is SAE 10W30 which John UK recommends and I swear by his advice; or the more traditional GL 1 90 gear oil, a mineral based oil. From what I am told the vescosity has nothing to do with the leaks, moreover it's how it was filled. The pros say put in 2 gallons initally, go read a book, then come back and top the system off. Probably would be a good idea to go finish the book before you fill the last gallon or so. I am told this is necessary due to possible worn cluth seal allowing oil to leak into the cluth housing and other places it shouldn't go. In so far as leaking at the drain plug I'd guess try some teflon tape around the threads on the plug or look for a crack around the housing. In so far as the PTO leaking I'd say it has to be a oil seal or gasket. My PTO shaft leaked from day one so rather than pulling mine and rebuilding it I ordered the 1 3/8 PTO shaft assembly as an upgrade and slid it in bolted it down, no problems. In my case I had a bad left side axle seal and ordered all the parts to replace seals, bearings and brakes since the leaking oil corrupted my left side brakes. (Doing both sides since I have it jacked up and blocked). Mine did not leak until I changed the fluid and the tempature got hot which I guess is just normal thermal expansion and if a seal etc. is worn it will leak. I like you was and am still very curious as to why it didn't leak before I changed fluid? Since the seals etc. are 1953 originals I figured it was time to replace them. If it still leaks then I wasted a couple hundred bucks a whole lot of time. The beer has been good and cold during the rebuild process so far.

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John UK

08-01-2011 12:02:34

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 Re: Transmission Fluid Leaking in reply to West T, 08-01-2011 10:10:42  
If you have filled it with 5W/30 then it could very well leak as it is very thin and isn't recommended. What was recommended however was 15W/30 and that doesn't normally leak as it is tried and tested. However if you fill your transmission with this oil and it does leak then it is the seals that need replacing. It is quite possible that the oil that was in the transmission originally before you changed it was much much heavier than this,due to age or being just incorrect grade, as we often find out when people write in. What you should do is make sure that you have drained ALL the oil from the transmission and that it isn't overfull. There are 3 drains on a TO20 or TO30 and on any of the TE20 series but only 2 drains on a 35 series. If you haven't completely drained ALL the oil then it will leak as it is overfull. What you can do is remove the bottom screw on one of the round side covers below the seat and allow any oil there to run out until it stops and that will be the correct level. The dipstick may not be the correct one and you should mark it with the new level when you have done this. There is also the danger that because you may have overfilled the transmission, oil will get onto the brakes and the Clutch. If as you say it is leaking from the drain plug, then it needs a new sealing washer, it will not stop leaking even if you tighten it. The PTO leaking is often caused by grass etc being wrapped around the PTO shaft and being wound into the seal and that will wreck it. Make sure that the oil is coming out of the front drain if it is on one of the grey tractors, as it can come out of the weep hole underneath at the front of the transmission and then run back to the drain plug area and you may think that it is the plug leaking....John

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