Do I have a problem? (Xmission oil pan plug)

[Steel15]

Below is an e-mail I just sent to Kubota but I wanted to get y'all's opinion?

Anyone ever have anything like this happen? Should not the hardness of the metal in the bolt be lesser than what the bolt is screwing into as it is easier to replace a stripped bolt than a stripped Xmission fluid pan? Does the plug in that pan HAVE to be more than hand tight? Thanks for any help or advice ya'll can provide!

Brett.

Background:We have a factory new B2920HDT that we purchased last Nov. We use the tractor on a small start up organic vegetable farm in PA. We do not have the capability to trailer the tractor.

Issue: After changing the transmission oil as called for after the initial 50hrs. of usage, I was tightening the drip pan plug closest to the rear left tire (I had already replaced the plugs near the rear-right tire and the mid-mount PTO and seated them to the same torque as they came from the factory), I had bare oily hands and was using a short handled socket wrench, torque wise I had just passed hand tight and was 1 to 1.5 full turns away from the factory torque tightness when all of a sudden it felt like the bolt might have stripped as the torque required to turn suddenly dropped way off. I extracted the bolt and its threads were fine, there were thin metal shavings in the threads of the bolt as if I was screwing it into light aluminum and had stripped those threads. I can not get that plug/bolt to tighten to the same torque level as the right side plug or anywhere near the torque it came with from the factory. It IS however just passed hand tight. I put a small bit of teflon tape on the bolt threads to see if that would improve the seal and allow it to tighten down but it still refuses to seat to the same level as the other two plugs. I have yet to refill the tractor with Transmission/hydraulic oil and start it back up again as I wanted to talk to y'all to see if I have an problem. As we are a startup organic vegetable farm the tractor is vital to our day to day operations so I would appreciate as rapid a response as y'all can manage . Thanks in advance for any help you can provide. Brett

 

[bp fick]

They make after market re-tapping plugs when this happens in the auto industry, especially the quick oil change places.

I might would carefully, carefully run a self tapping oil plug into that hole. Remember, it is going to self tap into rather soft metal. Do not over torque.
Take your old plug into an auto parts store and match up the size. The self tapping plug you want will seem the same size. I wouldn't try to force one in that was anything but JUST bigger than the old. Here's hoping for the best.

PS- You cannot have SUDT dripping all over your gardens. That is a no no in organic biz.

 

[KennyV]

I was 1 to 1.5 full turns away from the factory torque tightness

Brett...
The above statement seems rather ... odd.
After hand tight you will normally only add maybe 1/3 of A turn to get to full torque.
I will only guess that if you could turn it that much AFTER it was hand tight, you were cross threaded to begin with... It happens.

Like bp fick, suggests you can use the self tapping plugs... BUT they are very easy to cross thread with subsequent use, and you stand an excellent chance of buggering up the threads every-time you replace the plug.

One other thing with the self tappers. A drain plug is not sealing at the threads like a pipe plug. Pipe plugs have tapered threads. A drain plug seals with an oring or washer against the flat boss around the threaded hole. IF you do not get the self tapper perfectly straight it will meet the sealing point at an angle and leak.

If you do use a self tapping plug, use it only to cut the new threads... use a non tapered regular oversized plug as the permanent drain plug.

Myself I would drill out the old threads leaving clean straight hole and tap to a over size fine thread plug.
Use a definite oversize so as to avoid the possibility of inadvertently placing one of the other two factory plugs into your almost factory size hole. also get a torque wrench, it will pay for itself many times over in its lifetime. (most bolts and nuts fail from over tightening). KennyV

 

[KennyV]

BTW...
Thought I would also mention, while you are looking at drain plug fixes. You will see the rubber expanding stopper type. That may get you by for the short term... but you probably should not trust it to be a permanent fix. KennyV

 

[bp fick]

There is a more professional fix.

timesert.com

But, you need a quick, temporary fix. The timesert can be done during a slow time, like November or something.

 

[Steel15]

Yeah, when I say "hand tight" I mean with bare oil soaked fingers and I was just guessing on the # of turns, all I know is I had to apply a buncha force to loosen the bolts and applied the same amount of force to re-tighten the bolts after I'd drained the oil. worked fine on the bolt nearest the mid-mount PTO and the right rear tire but the left side pan seemed like it was made of soft aluminum.

Given that the bolt is currently just past hand tight do u think it'll be able to hold its seal? Do those pan bolts loosen often? How much pressure are they fighting under max load? Is it just gravity pulling on the oil or is it under pressure while engine is on?

 

[sms0000]

Brett...
The above statement seems rather ... odd.
After hand tight you will normally only add maybe 1/3 of A turn to get to full torque.
I will only guess that if you could turn it that much AFTER it was hand tight, you were cross threaded to begin with... It happens.

Like bp fick, suggests you can use the self tapping plugs... BUT they are very easy to cross thread with subsequent use, and you stand an excellent chance of buggering up the threads every-time you replace the plug.

One other thing with the self tappers. A drain plug is not sealing at the threads like a pipe plug. Pipe plugs have tapered threads. A drain plug seals with an oring or washer against the flat boss around the threaded hole. IF you do not get the self tapper perfectly straight it will meet the sealing point at an angle and leak.

If you do use a self tapping plug, use it only to cut the new threads... use a non tapered regular oversized plug as the permanent drain plug.

Myself I would drill out the old threads leaving clean straight hole and tap to a over size fine thread plug.
Use a definite oversize so as to avoid the possibility of inadvertently placing one of the other two factory plugs into your almost factory size hole. also get a torque wrench, it will pay for itself many times over in its lifetime. (most bolts and nuts fail from over tightening). KennyV

I agree I was thinking about 1/4 turn myself.........a word of advice if your going to talk torque specs......use the specs and a torque wrench. The amount of force required to break a bolt free doesn't mean much in terms of force needed to tighten it. It happens, I did it once but never again .

 

[Steel15]

Okay, disregard the talk of torque specs, all I can say is that the force needed to break the bolts free was fairly large, the force used to re-seat the other two bolts was waaay greater than the point at which the bolt in question failed. The manual talks about specific torque levels required on SOME of the bolts so I figured if it was sensitive they would have mentioned something on these pan plugs (they don't). Regardless, the point at which the bolt failed leads me to believe there was an issue with how the plug's hole was initially bored. These plugs don't really have delicate threads and I was so oiled up, on my back, and using such a small wrench that there was no way I could have generated enough force to jump threads on a 'normal' hole. So the sense I'm getting is this was a defect in materials that the pan was made out of. Shouldn't the bolt be of a softer steel than the hole it's being screwed into so if something is going to fail, the easily replaceable bolt strips as opposed to the crank/transmission case? What are the chances Kubota would replace the pan as the tractor should still be under warranty?

 

[KennyV]

Given that the bolt is currently just past hand tight do u think it'll be able to hold its seal? Do those pan bolts loosen often? How much pressure are they fighting under max load? Is it just gravity pulling on the oil or is it under pressure while engine is on?

You are not tightening against a pressure oil leak... You are torquing against vibration loosening and thermal expansion, dis similar metals expand at uneven rates.
If you do not know the absolute values ...
Drain plugs in...
Aluminum and other white metals torque to 180 to 240 INCH pounds.
Steel torque to 240 to 360 INCH pounds.
ALWAYS use a soft washer, fiber, aluminum, or copper... (it is the actual seal, takes up the variable thermal expansion)
KennyV
PS torque using an INCH pound wrench... A FOOT pound wrench is NOT accurate at the low end.

 

[KennyV]

all I can say is that the force needed to break the bolts free was fairly large, Shouldn't the bolt be of a softer steel than the hole it's being screwed into so if something is going to fail, the easily replaceable bolt strips as opposed to the crank/transmission case?


What are the chances Kubota would replace the pan as the tractor should still be under warranty?

Like sms0000 said... The amount of effort to loosen a fixture is never relative to how tight it was installed. Too many other factors there.

Most pans are cast soft metals and have adequate thread strength to hold a plug. The steel pans are normally thin and have fewer threads than the plug that goes into them. Any error will take out the female threads.
Take a little care removing nuts, bolts and other threaded fixtures... BUT take Great care replacing them... I learned that decades ago with the trial & error method. The error always took more time and $ than I had ...

Replacing a pan for stripped threads is not really necessary, there are easier less expensive and commonly acceptable fixes. Also the number of other things that are necessary to disrupt and remove/replace to change a case like you are talking about, would to me not be in your best interest.KennyV

 

[Steel15]

yep, the washers on those plugs look pretty specialized and I could tell that it was the washer that formed the seal. I was attempting to match the factory pressure levels on those washers when the thread got jumped. I guess I'll find out if slightly past 'hand tight' is enough pressure to hold the seal. Best case, Kubota writes back and says "yeah, we've had some issues with this in the past ur not the first one, we'll send a trailer out to get it and replace that part lickedy-split", worst case we've got an automotive repair place across the road from us I might go ask to see how much they'd charge to re-bore a drain plug hole and compare that to the self-boring plugs mentioned earlier.

 

[Steel15]

Thanks Kenny and all u other guys for the help. Sounds like a trip across the street to the car repair place might be my best bet. I'll refill the B2920 tomorrow with fluids and fire her up and see if she leaks, then I'll go ask the shop what they'd charge to fix that plug, if they say "**** no, we're a car shop not a tractor shop we don't want the liability issues that that would bring" then I'll look at the self-boring plug route.

 

[KennyV]

Like I said ... for a temporary fix, (It will get you through the summer and fall).

Get an expanding rubber plug. They stand the heat and will last BUT they are NOT reusable. They don't leak and can not fall out. They are not commonly used because a lot of people do not understand one time use. KennyV

 

[bp fick]

A self tapping plug will not do any more damage than what is already done, if you don't go up size.
There are lots of heli-coil type products which will do a nice job. These Kubotas, like a Honda or other Japanese machine, either cycle or auto, use a different philosophy than what developed here in N.A. Having a Honda for over 10 years, I have gotten used to changing out the drain plug gasket every other time. SOP. Japan was using cast aluminum and finer, softer hardware while we were still pushing around 6000 lb, cast iron avenue cruisers. There is a kind of mental adjustment to feeling things a little differently when wrenching a Honda or Kubota. It isn't a 65 Chrysler with a slant 6 or 318, that's for sure.

Relax. 1000s of bolts get stripped out everyday all over the world. Put your feet up and watch a baseball game or something. It'll be fine.

 

[KennyV]

bp fick is so right...
This I am sure seems like a big problem... but is quite common. Easy fix, several different ways.
The shop across the street would most likely jump at the chance to get the work... Plus be a good neighbor. Most likely will come across the street and repair it where it sets BEFORE you put oil in it. KennyV

 

[Steel15]

Yup, after doing a bit more reading it seems that the rubber plugs are preferable to the self-tapping fixes, even read one guy who said he just bought a couple of rubber plugs and just replaces them every time he changes the oil. As I'm not due to change HST oil again for another 350 hours, that could be like 2 years from now. Is there really nothing naughty about using a rubber plug through 2 years of use and temps ranging from -20 to 90 deg. F and then just slapping another new rubber plug in there the next time I change HST oil? If so I'll sleep alot better tonight. And thanks for the advice bp fick on the different mind-set between maintaining the Japan/Kubota stuff and the HMMVW and Bradleys I was used to maintaining in the Army. No place for brute force on the delicate flower of a Kubota tractor let alone drain pans (there are TON of hits when you search 'stripped drain plug') in general. I know that now.

 

[638]

What is the size of the existing plug (diameter and thread pitch)? Knowing that, I can recomend the next size larger (english and/or metric) that the hole can be tapped out to. Then all you have to do is buy that size bolt, cut it to length, and put a gasket on it.

 

[KennyV]

You could most likely run a 1000 hours or 10 years on the expanding rubber plug. What you can't do is remove and reuse it.
BTW your temp swing is NOT -20 to 90 degrees...
It's closer to -20 to 200 degrees... Hydro oil gets hot. Got to go now , it's been fun . good luck and what everyou do Will Work ... KennyV

 

[bp fick]

What is the size of the existing plug (diameter and thread pitch)? Knowing that, I can recomend the next size larger (english and/or metric) that the hole can be tapped out to. Then all you have to do is buy that size bolt, cut it to length, and put a gasket on it.

Exactly how I'd do mine, if this were in my shop. I'd probably grab the next size up, which would/might even be SAE, so as to just go up a step. Grab my tap and cut the hole for a new plug. I'd load it with heavy grease to catch the cuttings. Actually, since the case is empty, it would be an easy flush anyhow. No worries. I've tapped new threads countless times. But again, this is essentially what a quality, self tapping drain plug does anyhow.

 

[wdchyd]

There is a more professional fix.

timesert.com

But, you need a quick, temporary fix. The timesert can be done during a slow time, like November or something.

Nice tip BP Fick,

I'll be looking into these for future use, I have a motorcycle/snowmobile/boat dealer next door at work and just a couple of days ago they came in looking for an alternative to "Helicoil".....their problem was tapping out perfectly straight and perpendicular, gaskets were not sealing, this is perfect for that application....the drain holes for some machines they service are recessed and are hard to line up flat.....this will work perfectly for them.....

Thanx, Bill