HST drain plug dripping

Tractor Gal

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If the plug won’t tighten and hold to the point there’s no chance it’s going to randomly fall out then obviously you have to go with one of the various options for rethreading oversized, heli-coil, etc.

If it WILL pull up tight and is secure but is leaking because the cross threaded state it’s in has it a bit too crooked to seal properly that’s a different issue. I had a Jeep Cherokee with a straight six quite a few years ago that had that problem. My wife drove it and it needed an oil change while I was out of town for work for several weeks. When I got home she told me it had been leaking ever since the oil change. She’d taken it back once and it was better but still leaking whether running or not. Turned out they cross threaded the plug, then put in an oversized “repair” plug but didn’t get it lined up straight so it wasn’t in any danger of falling out, but the copper washer wouldn’t seal correctly. So, for the next 150,000 miles I would drain the oil quite thoroughly, clean the mating surface of the oil pan and plug with whatever grease/oil solvent was handy, put a bit of RTV silicone around the hole in the pan, install the plug, and then wait several hours before refilling with oil. Took pretty much all day to change the oil, of course with many lengthy breaks, but it never leaked and the silicone didn’t create any mechanical resistance to removal at next oil change.

Could be I’m lazy but if the plug was secure and just not sealing, I’d probably do that before I busted out the drill bit and tap, potentially putting drillings in the pan.
Yes, this makes perfect sense, NCL4701. With that in mind, I'm going to try the Loctite 518 that was suggested. Thanks for taking time to respond.

TG
 

fried1765

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TheOldHokie

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When I got this used tractor, the HST was slowly dripping. I have tried to address the drip to stop it but have only made a little progress. The threads in the transmission case are in bad shape. I've searched
on this forum to read solutions that different people have tried.

I've considered...and am still considering...a helicoil but have concerns. It seems that it would be easy...as well as common...to bungle the job. :) I got a new bolt and when it threads in, it does begin to grab but then just runs out of thread, it seems.

There are lots of opinions for solutions. I do not want to cause more issues by new tapping, etc. What are some solutions to try that would not entail re-tapping? Would rubber 0-ring be a possibility? I made a leather gasket hoping it would form to the hole and it did help some but there is still dripping. I've asked the Kubota dealer for the specs on this drain plug so that I can get right sizing...nothing was available in the WSM or online that I could find.

Thanks for any help!

Tractor Gal
Imstalling a thread repair insert in something like that is pretty easy.. your drill is only a few thousandths over. Then it's just run in the tap followed by the insert.

Dan
 
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fried1765

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Imstalling a thread repair insert in something like that is pretty easy.. your drill is only a few thousandths over. Then it's just run in the tap followed by the insert.

Dan
I do hope that the guy who invented the Helicoil is a multi millionaire!
 

TheOldHokie

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I suppose.......
But,...... likely a "man" came up with the idea/concept.
A "company" took the credit.....and the gravy!
More likely a joint engineering effort:

The Heli-Coil system entered American industrial life in 1936 as the Aero-Thread Screw Thread System. It was developed by an engineer, Harold Caminez, as a solution to the notch effect or stress concentration at the root of the 60 degree angle of the conventional screw thread used on Allison aircraft engines.

In any event it was licensed away and generated millions in corporate profit.

Dan
 

Nicksacco

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Ha! I wonder why the 2-yr old thread popped up? Never even noticed the date, but interesting info about the Heli-Coil nonetheless!

"She either has it fixed by now,........ or all the oil has already leaked out. " - Hilarious!
 

Tractor Gal

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I thought about replying again to the thread but figured this kind of nuisance can't hold a candle to some of the repairs many are doing and are asking about.

So...here's the story. Yes, I got it fixed...finally after 3 years! After using the tractor, I would have to put a catch can under the drain bolt. Sometimes I would forget only to find a puddle in the garage. At that time I would try to kick myself but could never manage contact.

It wasn't time to replace the hydraulic fluid but I decided while I was trying to fix this, I would go ahead and change fluid and filter. Lo and behold, when I removed the drain plug, the time sert came out with it! When it was inserted, it was to have some thread locker so apparently that worked but maybe the housing was never fully free of oil and it didn't hold. Or, of course, maybe I didn't do it right. So I drained the fluid, waited 2 days and installed another time sert. The "kit" contains more than one sert. Put a quart of fluid back in and drip, drip, drip.

Anyway, I drained that fluid and waited 2 more days.I put a rag into the drain to catch the fluid instead of letting it spread to the housing. JB Weld to the rescue....so I thought. Added a quart. Nope, still drips...not as much but still dripping.

So, since I had done the JB Weld to repair the crack and had installed a new sert, the only way to find something was to put the plug back in, add a quart or so of fluid and lay under that consarned machine to find the drip location. I had put the JD red dye into the fluid so I could see easily. There it was!

The fluid was coming out between the sert and the housing. I'm not sure how that was happening, but that was the problem. I remembered hearing about copper gaskets which would mold more to the surface and I had some of those onhand. Ba-boom....sealed it!

I put a gallon of fluid in and waited...no drip. Added remainder of fluid and all was good. As they say, "no runs, no drips, no errors." I am thrilled. Every time I pass the little orange thing, I smile. I've used it a couple of times with no problems of dripping. My garage is thankful.

Forgive me for not posting. I just didn't think that kind of thing was of much interest to anyone other than me. Now, I've get to use this for a lot of hours before the need to change the fluid again. That should be interesting...as I do have spare copper gaskets! Thanks all for suggestions and encouragement.

TG
 
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TheOldHokie

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I thought about replying again to the thread but figured this kind of nuisance can't hold a candle to some of the repairs many are doing and are asking about.

So...here's the story. Yes, I got it fixed...finally after 3 years! After using the tractor, I would have to put a catch can under the drain bolt. Sometimes I would forget only to find a puddle in the garage. At that time I would try to kick myself but could never manage contact.

It wasn't time to replace the hydraulic fluid but I decided while I was trying to fix this, I would go ahead and change fluid and filter. Lo and behold, when I removed the drain plug, the time sert came out with it! When it was inserted, it was to have some thread locker so apparently that worked but maybe the housing was never fully free of oil and it didn't hold. Or, of course, maybe I didn't do it right. So I drained the fluid, waited 2 days and installed another time sert. The "kit" contains more than one sert. Put a quart of fluid back in and drip, drip, drip.

Anyway, I drained that fluid and waited 2 more days.I put a rag into the drain to catch the fluid instead of letting it spread to the housing. JB Weld to the rescue....so I thought. Added a quart. Nope, still drips...not as much but still dripping.

So, since I had done the JB Weld to repair the crack and had installed a new sert, the only way to find something was to put the plug back in, add a quart or so of fluid and lay under that consarned machine to find the drip location. I had put the JD red dye into the fluid so I could see easily. There it was!

The fluid was coming out between the sert and the housing. I'm not sure how that was happening, but that was the problem. I remembered hearing about copper gaskets which would mold more to the surface and I had some of those onhand. Ba-boom....sealed it!

I put a gallon of fluid in and waited...no drip. Added remainder of fluid and all was good. As they say, "no runs, no drips, no errors." I am thrilled. Every time I pass the little orange thing, I smile. I've used it a couple of times with no problems of dripping. My garage is thankful.

Forgive me for not posting. I just didn't think that kind of thing was of much interest to anyone other than me. Now, I've get to use this for a lot of hours before the need to change the fluid again. That should be interesting...as I do have spare copper gaskets! Thanks all for suggestions and encouragement.

TG
As you discovered straight threads are not liquid/pressure tight. You gotta have a gasket under the head of the plug.

Dan
 

Tractor Gal

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Would trying a rubber/metal drain plug gasket be a suitable place to start if you are still able to apply appropriate torque to the threads?
No, a rubber gasket would not work. A new drain plug came with one but it didn't stop the leaking. That's why I remembered about the copper gaskets. Good idea, though, but believe me, I had tried everything!

TG
 

D2Cat

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No, a rubber gasket would not work. A new drain plug came with one but it didn't stop the leaking. That's why I remembered about the copper gaskets. Good idea, though, but believe me, I had tried everything!

TG
I think Mikester is referring to a steel washer that has a molded neoprene EPDM on one side. They seal good!
 

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Tractor Gal

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I think Mikester is referring to a steel washer that has a molded neoprene EPDM on one side. The seal good!
Good to know, D2Cat. Thanks for the additional info. Since the copper is working, I'm not doing anything at the moment, but I may get some of these to have on hand. At some point, that drain point will have to come out!

TG
 
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lugbolt

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don't know what tractor you have but I've repaired a number of them over the years. I assume this is an aluminum case and not cast steel?

If it's 12mm, that's just under 1/2". So you could try to run a 1/2"-20 tap up into it and see if it'll cut a thread. Put some grease on the tap before you start and back it out often to clear the chip, and re-grease. Then dump a little fluid into the transmsision and let it drain out-that'll force any chips that may have gotten into the transmission back out via flowing fluid.

Another option, thread it with a 3/8NPT pipe tap, but I'd just as soon use a regular bolt as opposed to pipe plugs.

There really are but a few options in cases like this. Replace the transmission case. Re-thread. Repair thread with heli-coil or time-sert. Or, rig it.

doing it professionally the best option to avoid comeback is to replace the case. But I always gave the customer the other options and the vast majority of the time they chose one of the other options-usually repairing the thread. Never had one fail or come back for any other issue related to the repair.
 

Tractor Gal

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don't know what tractor you have but I've repaired a number of them over the years. I assume this is an aluminum case and not cast steel?

If it's 12mm, that's just under 1/2". So you could try to run a 1/2"-20 tap up into it and see if it'll cut a thread. Put some grease on the tap before you start and back it out often to clear the chip, and re-grease. Then dump a little fluid into the transmsision and let it drain out-that'll force any chips that may have gotten into the transmission back out via flowing fluid.

Another option, thread it with a 3/8NPT pipe tap, but I'd just as soon use a regular bolt as opposed to pipe plugs.

There really are but a few options in cases like this. Replace the transmission case. Re-thread. Repair thread with heli-coil or time-sert. Or, rig it.

doing it professionally the best option to avoid comeback is to replace the case. But I always gave the customer the other options and the vast majority of the time they chose one of the other options-usually repairing the thread. Never had one fail or come back for any other issue related to the repair.
Thanks for your post, lugbolt. Got it licked for now! We'll see how things continue to go...hopefully it continues to go well.

TG
 

Tractor Gal

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I think Mikester is referring to a steel washer that has a molded neoprene EPDM on one side. They seal good!
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If possible, would someone offer a bit more info on these washers...that is the steel with neoprene. My "repaired" dripping drain plug is beginning to drip again. Wouldn't you know it? Never pays to get too haughty about repairing something, but I digress. It is not much of a drip as in the past but I want to fix it. These neoprene washers seem like a good thing to try.

I went to Lowe's yesterday as their site says they have these but upon further examination, they do not have a large enough diameter for the drain plug. It is 12.5mm. I looked briefly online but the description is not enough for me to know what size to locate. The Lowe's largest stock was #8 but I don't know how to interpret that number. It would not be metric. Any help for the correct sizing for a 12.5 mm drain plug would be great as I would like to try this. Online has boxes with multiple washers. I would only want to buy 2 or 3, at most. Thanks for any help.

Tractor Gal
 

Nicksacco

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Hi @Tractor Gal

12.5mm is about 1/2 inch.
These washers are Belleville washers due to their concave shape.

Check this out https://www.bsstainless.com/american-screw-sizes
and

It appears there isn't a number for 12.7mm

But there are Belleville washers for M12 bolts and I cannot find a number for bonded epdm at 12mm.
It seems #14 is largest.


Maybe someone knows if they exist.
In lieu of that, you could use some epdm or similar obtained from a hydraulic shop (cut your own) and a regular 12mm washer - a thick one or double up 2 thin ones.

Another possibility might be copper crush washers such as those used in motorcycles for oil drain plugs.

I used that concept on some worrisome hydraulic lines that wouldn't seal correctly.

Well heck - check this out - note the title to search on "
Bonded Sealing Washers M12

 
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