Transmission drain plug B 2920

[Tractorrr]

I was replacing the transmission fluid that was lost when I changed the suction filter and overfilled it a little. I took the drain plug off to drain some of the fluid to get it back into normal range. When I hand tightened the drain plug back on it gets to a certain tightness but then loosens back up after that not allowing it to go back on right. It is able to go back on fairly tight but this is pretty frustrating as I'm not sure what would be causing this. Maybe the threads are stripped. This is the first time I have taken this plug off on a fairly new B2920. Any advice on this would be appreciated. Maybe I need to try a new drain plug? Anyone ever had something like this happen? Maybe I should leave it the way it is as it doesn't seem to be dripping once I get it back on the best I can. This is the drain plug by the mid PTO.

 

[s219]

Sounds stripped to me. Could try wrapping the plug in teflon pipe tape to gain a little more bite before it gives up.

 

[Katahdin]

A coworker of mine just did the same thing to his B. The pan was aluminum so its easy to over torque and strip. The dealer retapped the threads and put in a larger plug.

 

[sixdogs]

Sometimes you can add an extra washer and that will work by keeping the stripped portion of the bolt away from the threads.

 

[Tractorrr]

Thanks for the replies, gives me some ideas to work with. Just wish this would have gone smoothly. Glad to know this has happened before though.

 

[Tractorrr]

Got it wrapped in thread tape. Am able to tighten it more so I will probably just leave it alone now. Thanks.

 

[madamos]

I recommend a proper repair, either drill and tap oversize or a thread repair like a Helicoil or Timesert. If the plug is just wedged using Teflon tape it could vibrate loose and even drop out unexpectedly which would at the very least be a big mess and at worst if not detected, result in equipment damage.

Paul

 

[s219]

Depends on how tight he was able to get it. Plenty of threaded pipe connections in hydraulics use some sort of teflon -- usually dope, but can be tape if it is carefully wrapped and applied. We don't worry about them backing out. If it was me, I'd really try to assess it before deciding if re-tapping was needed.

 

[madamos]

I am ok with Teflon tape/paste when used for tapered pipe threads that they are intended to be used with.

My concern is that if the threads are physically damaged and the bolt(plug) won't take the required torque that is a sign that it just "feels" tighter and as the tape cold flows it will soon loosen.

I am a maintenance instructor at a nuclear power plant and correct bolt tensioning is one of the classes that I teach.

Paul

 

[Tractorrr]

I agree with getting the proper fix. Wrapping the bolt in thread tape may only be a temporary fix for now.