View Full Version : Bunton Transmission Leak

03-25-2007, 02:05 AM
I have a an older model Bunton walk behind that has a transmission leak out the right side. I'm attaching a pic to help show what I have. I'm hoping you guys can help me with the following:

1. What type of oil to fill with?
2. How much do I put in it?
3. Is the small top screw the fill plug?
4. How difficult would it be to fix the leak?

Thanks in advance.


03-25-2007, 08:21 AM
have had a few buntons over the years, the small top screw is the vent, probably pluged cauz its leaking out the side....i still use a 48 bunton walkbehind with a 2 wheel velke..5 years ago i replaced the old gear oil with mobil shc 634 synthetic gear oil, it has never overheated, smoked or leaked.all my other buntons did before i got rid of them or they died...one time i put the mobil in an oveheated 36" gear box that striped most of the brass and it went another year before its engine blew after 15 years....u do have a small leak out the side, and u can reseal it but u will have to tear the box apart to do it....since learning about the mobil shc 634 thats all i use in a gear box, I wouldn't fix that leak, its small and will probably stop if u put the mobil in it...ive allways pulled the 4 top screwss to fill. the side plug is for draining and when u refill the box fill it to the top of the drain plug only, gear oil expands big time. u can get the mobil here http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemId=1611715718 its a little pricey, but u wont have to change it for at least 10 years.

03-25-2007, 02:42 PM
Yes, make sure it is not getting overfilled, first of all. It has to be filled by the side plug - not the top (just in case it was). There are seal kits for these, and they really aren't that difficult to do. I had a couple of these mowers (JD). The idea of the synthetic is good, too.

03-27-2007, 10:43 PM
I have not been able to find the gear oil in the link above but I did find http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemId=1611574196 except in 75W-140. Will this work ok otherwise I'll just order what was previously listed?

Thanks for all your help.

03-29-2007, 09:59 PM
Can anyone help me on this? I bought http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemId=1611574196 except the 75w-140 but I want to make sure I'm not going to cause any problems by using this.

I just can't find the Mobile SHC 634 in any shops and was hoping to get something soon.

Any other suggestions or should I just order the Mobile SHC 634?


03-30-2007, 09:45 PM
just order it from grainger, call them up : Synthetic Gear Oil, SAE Grade 140, ISO Viscosity Grade 460, Viscosity Index 159, Viscosity SUS @ 100 Degrees Fahrenheit 2236, Flash Point 460 Degrees Fahrenheit, Pour Point -20 Degrees Fahrenheit, Container Size 1 Quarts, 634 Formula Grainger Item # 4ZF30

If u google it u might find it easier....this is single weight oil and it works...was told to use it years ago from mower mechanic,do yerself a favor and fill it from the top cauz filling it from the side plug will take u forever..just dont fill it past the bottom of the side plug