Broken Oil Drain Plug

[lynnmor]

Hundreds of thousands if not millions of helicoils used. They are even installed in brand new parts to strengthen threads. A dab of high strength Loctite and they wont back out.

Installation is a 15 minute job and so simple a caveman....

Dan

I made various parts for NASA, they want inserts (Helicoils) in all tapped holes. When using inserts, keep in mind that the sealing washer needs to go well beyond the insert diameter.

 

[dlm]

On closer inspection of the removed plug, I noticed that the thread near the bolt head is full of metal. The bolt looks intact, so it seems like whoever said I stripped the pan thread was on the money.

 

[TheOldHokie]

On closer inspection of the removed plug, I noticed that the thread near the bolt head is full of metal. The bolt looks intact, so it seems like whoever said I stripped the pan thread was on the money.

That is the typical failure under shear. Female thread almost always pulls out before the male. Encyclopedias have been written on why.

Dan

 

[Russell King]

On closer inspection of the removed plug, I noticed that the thread near the bolt head is full of metal. The bolt looks intact, so it seems like whoever said I stripped the pan thread was on the money.

If you look at the plug, I see several plug threads that are full of the oil pan threads.

I think I would be thinking about going up one plug size and threading the pan (bung) that size. But you will have to measure the OD of the bung to see if it is large enough diameter for the sealing washer of the larger plug. And then where can you get that plug?

Another plan could be to get a new part machined with the same or smaller plug hole and sealing surface made. Then you are sure the surface is perpendicular to the plug thread. The outer diameter could be threaded like a bolt to screw into the existing drain pan bung. You could thread that to the next convenient thread size to have some wall thickness left in the plug.

Then use loctite red or whatever you like to install the new plug (adapter) into the drain hole. Just clean everything about 5 times so the surface is clean enough that the thread locker stays in place and seals well.

More costly than a helicoil repair but has the benefit of having a better surface seal at the drain plug surface.

Good luck

 

[GeoHorn]

So-called ‘helicois” are intended for physical attachment…. less-so for leak-proof plugs.

As before: Drill/Ream to the next larger size… Tap…and install oversized plug.

IMO

 

[TheOldHokie]

So-called ‘helicois” are intended for physical attachment…. less-so for leak-proof plugs.

As before: Drill/Ream to the next larger size… Tap…and install oversized plug.

IMO

Sheesh. You giys can make a mountain out of a mole hill.

The virtue of a helicoil is it restores the bolt hole to OEM size and thread. allowing you to use an OEM plug. The threads on the "plug" do not seal - they "attach" * (clamp) a sealing washer to the exterior.

If using a non-OEM plug is not a concern clean the hole up with a 5/16 (8 mm) drill bit. You will take nothing out but the remnants of the original 8 mm thread and a blind man can do it. Now tap 3/8-24 UNF and use an ordinary UNF cap screw and 3/8 copper crush washer.

Either way its an easy 15 minute job and will be as good as or better than OEM.

Dan

 

[Soopitup]

-The easiest thing is to retap the existing thread. Period.
-If the existing thread is no good the next easiest thing is to tap the same size with a different thread.
-If there's not enough material for that the next easiest thing is to drill the next size up and tap new threads.
-If you're stuck on using the original plug size or you can't easily find a plug the next size up a helicoil will work.

Sometimes a helicoil is necessary. I've used them before, and I'll use them in the future. For general mechanical use they should be a last resort.
Using a cheap kit for a hole that will see repeated use is asking for issues down the road.
If that's all that works, do it. But try better options first.

I made various parts for NASA, they want inserts (Helicoils) in all tapped holes. When using inserts, keep in mind that the sealing washer needs to go well beyond the insert diameter.

The reasons NASA uses helicoils are completely irrelevant to using one in a tractor oil pan.
I believe NASA also requires a positive lock (like safety wire) on all bolts. Does the oil pan plug need this too?
And, something tells me that (or a similar) helicoil kit isn't close to NASA engineering standards.

Hundreds of thousands if not millions of helicoils used. They are even installed in brand new parts to strengthen threads. A dab of high strength Loctite and they wont back out.

Installation is a 15 minute job and so simple a caveman....

Dan

So simple a caveman?
You must not have much experience with the average thumb fingered bufoon trying to turn wrenches (that's not directed at the OP, just a general observation).
It's easy to cram one in a hole. It's apparently not so easy to do it correctly.

Probably billions of helicoils used. I've dealt with plenty of them. Over many years. Both installed myself and ones others have installed.
A cheap Amazon helicoil isn't going to be as strong as the steel in the bung.
And the entire helicoil backing out is easy. It's more difficult when a portion of the helicoil comes out like a broken spring.

 

[TheOldHokie]

-The easiest thing is to retap the existing thread. Period.
-If the existing thread is no good the next easiest thing is to tap the same size with a different thread.
-If there's not enough material for that the next easiest thing is to drill the next size up and tap new threads.
-If you're stuck on using the original plug size or you can't easily find a plug the next size up a helicoil will work.

Sometimes a helicoil is necessary. I've used them before, and I'll use them in the future. For general mechanical use they should be a last resort.
Using a cheap kit for a hole that will see repeated use is asking for issues down the road.
If that's all that works, do it. But try better options first.



The reasons NASA uses helicoils are completely irrelevant to using one in a tractor oil pan.
I believe NASA also requires a positive lock (like safety wire) on all bolts. Does the oil pan plug need this too?
And, something tells me that (or a similar) helicoil kit isn't close to NASA engineering standards.




So simple a caveman?
You must not have much experience with the average thumb fingered bufoon trying to turn wrenches (that's not directed at the OP, just a general observation).
It's easy to cram one in a hole. It's apparently not so easy to do it correctly.

Probably billions of helicoils used. I've dealt with plenty of them. Over many years. Both installed myself and ones others have installed.
A cheap Amazon helicoil isn't going to be as strong as the steel in the bung.
And the entire helicoil backing out is easy. It's more difficult when a portion of the helicoil comes out like a broken spring.

An STI tap is just a tap in a special oversize - 2 x thread height. Running it in the hole is no different than tapping the parent metal for a standard fastener. If you can do one you can do the other. When you screw the helical thread repair insert into the STI thread you restore the standard size and pitch.

NASA and many other manufacturers use them in the NEW manufacturing process because they are stronger and more durable than cut threads in parent metal. Likewise stripped parent metal threads repaired with a helical STI will be stronger and more durable than the original thread. Thats an engineering fact supported by reams of testing.

Now to further muddy the waters we have added FUD about STI taps and inserts purchased from Amazon to the discussion. Apparently using them to repair stripped threads in a lousy oil pan drain bung poses a mortal threat to your tractor.

This whole conversation has gone loco and if the OP has any sense he has already clicked the ignore button.

Dan

 

[GeoHorn]

You still reading this OP..?? You’d better use a helicoil and a sealing-washer or you’re an idiot….. Oh… Wait… No, that’s harsh.…

….If you’re still merely Reading…. (therefore you’d best not reply)…..

Yeah. That’s the ticket.

 

[Runs With Scissors]

Way back in the day, the Grumman Tech Rep (Max) told me that the reason they use Heli-coils from the factory on some parts is because, in aluminum they are stronger than if they just tapped the aluminum part itself.

And you did not want to argue with Max....especially hung over.

He went on a big explanation about how and why, but since I was hung over and just wanted to get out of the sun, I accepted his explanation and have installed many of them successfully over the years. (especially on transmission pan holes)


And too the OP .....GREAT JOB on thinking outside the box!!!!!!

 

[hagrid]

@dlm: what engine oil were you using that caused your drain plug to strip out?

 

[lynnmor]

-The easiest thing is to retap the existing thread. Period.
-If the existing thread is no good the next easiest thing is to tap the same size with a different thread.

Running two different thread pitches in the same hole makes absolutely no sense, you are just removing even more metal from the damaged hole.

 

[Soopitup]

NASA and many other manufacturers use them in the NEW manufacturing process because they are stronger and more durable than cut threads in parent metal. Likewise stripped parent metal threads repaired with a helical STI will be stronger and more durable than the original thread. Thats an engineering fact supported by reams of testing.

Now to further muddy the waters we have added FUD about STI taps and inserts purchased from Amazon to the discussion. Apparently using them to repair stripped threads in a lousy oil pan drain bung poses a mortal threat to your tractor.

In the short time I've been here you're one of the most respected members here. You're obviously very intelligent, and your advice is reasoned, complete, and extremely helpful.
I've benefited multiple times from it myself, and I greatly appreciate it.
I'm not sure why the "mortal threat" comment is there; I certainly never implied or stated anything close to that. And it runs contrary to your usual quality of discourse.


How much of that strength is because the parent material is a softer material, like aluminum or delrin?
There are also other reasons helicoils are used, aside from thread strength. Which have nothing to do with an oil drain plug repair.

NASA engineering (and industrial to a lesser extent) is held to a much higher standard than regular mechanic fixes, never mind backyard fixes.
Tool quality, machining accuracy, and material quality are more demanding than any repair the OP is going to do. And those higher standards directly effect the thread quality.

Do you really think if the OP (or you or I) helicoils that hole it would hold up to NASA testing?

What your effectively saying is because a NASA tire can withstand X amount of heat/stress any other tire should be able to do the same.

My original comment wasn't an observation on the advisability of using helicoils in general, it was about using a helicoil in this specific instance.

As I've already stated, I've used helicoils many times. They definitely have their place.
If the metal is completely shot, I would use a helicoil too.
My point was simply that they shouldn't be the very first option if thread is damaged, especially something that's going to be regularly removed and reinstalled, like an oil drain plug. There are easier, better options to try first FOR THIS SPECIFIC FIX.

@dlm: what engine oil were you using that caused your drain plug to strip out?

Probably Shell Rotella. I heard that stuff is crap....

Running two different thread pitches in the same hole makes absolutely no sense, you are just removing even more metal from the damaged hole.

Changing the pitch and location of the thread sometimes gives it enough strength to hold.
Sometimes it works and sometimes it doesn't.
It's just the next step up before you make the hole larger.
I wouldn't use it on all repairs ( a head bolt for example ), but for this low torque hole it may work.


*To clarify, my aversion to helicoils in this particular instance is
-the difficulty in drilling/tapping/installing the helicoil straight and true while lying on your back underneath the tractor. The quality of the hole effects how well the helicoil will hold, and if the helicoil ends up crooked it can impact how well the plug will seal.
-the difficulty in completely cleaning the threads of oil residue
-the likelihood of the first thread to "unwind" itself over time with repeated use

If you do use a helicoil (considering the damage to the threads you may have to), make sure
-it's not longer or inserted further than the welded bung
-use blue thread sealant (red is too permanent for most things IMO) to lube/lock the helicoil in place
-clean the new threads well so the thread sealant can bond
-don't just use a dab of sealant, you want all the threads coated
-make sure the helicoil is installed a half turn or so past flush with the sealing surface.*

 

[TheOldHokie]

@dlm: what engine oil were you using that caused your drain plug to strip out?

In the short time I've been here you're one of the most respected members here. You're obviously very intelligent, and your advice is reasoned, complete, and extremely helpful.
I've benefited multiple times from it myself, and I greatly appreciate it.
I'm not sure why the "mortal threat" comment is there; I certainly never implied or stated anything close to that. And it runs contrary to your usual quality of discourse.


How much of that strength is because the parent material is a softer material, like aluminum or delrin?
There are also other reasons helicoils are used, aside from thread strength. Which have nothing to do with an oil drain plug repair.

NASA engineering (and industrial to a lesser extent) is held to a much higher standard than regular mechanic fixes, never mind backyard fixes.
Tool quality, machining accuracy, and material quality are more demanding than any repair the OP is going to do. And those higher standards directly effect the thread quality.

Do you really think if the OP (or you or I) helicoils that hole it would hold up to NASA testing?

What your effectively saying is because a NASA tire can withstand X amount of heat/stress any other tire should be able to do the same.

My original comment wasn't an observation on the advisability of using helicoils in general, it was about using a helicoil in this specific instance.

As I've already stated, I've used helicoils many times. They definitely have their place.
If the metal is completely shot, I would use a helicoil too.
My point was simply that they shouldn't be the very first option if thread is damaged, especially something that's going to be regularly removed and reinstalled, like an oil drain plug. There are easier, better options to try first FOR THIS SPECIFIC FIX.


Probably Shell Rotella. I heard that stuff is crap....



Changing the pitch and location of the thread sometimes gives it enough strength to hold.
Sometimes it works and sometimes it doesn't.
It's just the next step up before you make the hole larger.
I wouldn't use it on all repairs ( a head bolt for example ), but for this low torque hole it may work.

Your logic is flawed in many ways including your inference as to what what I an saying. I will make my meaning short and simple:

Helical thread repair inserts strengthen just about every application in which they are used including a mild carbon steel drain bung.

There are a myriad of reasons for that and they are well documented in the literature but I will give you four very basic ones:

1. An ordinary run of the mill STI has a tensile strength of 200-250 KSI, a Rockwell hardness of 45-50 RC, and a surface finish of 8-16 micro inches. That is far better than any parent metal tapped hole you are ever likely to encounter.
2. The major diameter of an STI is slightly larger than the major diameter of the original tapped hole. That means there is more parent metal area in shear and the pullout strength of the female thread in the parent metal is increased.
3. The shear and tensile strength of the STI internal thread is greater than the parent metal and since the area in shear of that thread form is the same as the original parent metal that means the internal thread is stronger than the original Additionally improved surface finish and hardness of the internal thread reduces the effects of galling and erosion during multiple assembly cycles..
4. The physical properties of the insert act as an isolator protecting the parent metal from the effects of fatigue.

That is why NASA and many ordinary OEMs frequently specify inserts rather than parent metal threads. It benefits their higher tech applications and it will benefit your lower tech ones as well.

If you simply don't like them and want to use an alternative repair that's up to you. But please do not misrepresent their performance to people that might actually choose to use and benefit from them. Hopefully the OP has not been run off by this train wreck and is now well informed as to his different repair options.

Dan

 

[Runs With Scissors]

Your logic is flawed in many ways including your inference as to what what I an saying. I will make my meaning short and simple:

Helical thread repair inserts strengthen just about every application in which they are used including a mild carbon steel drain bung.

There are a myriad of reasons for that and they are well documented in the literature but I will give you four very basic ones:

1. An ordinary run of the mill STI has a tensile strength of 200-250 KSI, a Rockwell hardness of 45-50 RC, and a surface finish of 8-16 micro inches. That is far better than any parent metal tapped hole you are ever likely to encounter.
2. The major diameter of an STI is slightly larger than the major diameter of the original tapped hole. That means there is more parent metal area in shear and the pullout strength of the female thread in the parent metal is increased.
3. The shear and tensile strength of the STI internal thread is greater than the parent metal and since the area in shear of that thread form is the same as the original parent metal that means the internal thread is stronger than the original Additionally improved surface finish and hardness of the internal thread reduces the effects of galling and erosion during multiple assembly cycles..
4. The physical properties of the insert act as an isolator protecting the parent metal from the effects of fatigue.

That is why NASA and many ordinary OEMs frequently specify inserts rather than parent metal threads. It benefits their higher tech applications and it will benefit your lower tech ones as well.

If you simply don't like them and want to use an alternative repair that's up to you. But please do not misrepresent their performance to people that might actually choose to use and benefit from them. Hopefully the OP has not been run off by this train wreck and is now well informed as to his different repair options.

Dan

You forgot one Dan........

5. Because Max said so, and nobody F's with Max.

 

[BobInSD]

By a quality set. I use Irwin, straight flute extractors and they work good. https://bcfasteners.com/shop/irwin-53645-straight-flute-screw-extractors-6-piece-set/

While these are not the tool for THIS job, having a good set on hand is a good idea. I also like to keep some left-handed drill bits around to use before (and if the extremely lucky, instead of) the EZ-outs.

Obviously, if it's already spinning you don't need an ez-out.

 

[fried1765]

While these are not the tool for THIS job, having a good set on hand is a good idea. I also like to keep some left-handed drill bits around to use before (and if the extremely lucky, instead of) the EZ-outs.

Obviously, if it's already spinning you don't need an ez-out.

I have two complete sets of 1/8"-1/2" left hand bits.
They are my go to "extractors".
I just used one to save an cast aluminum air compressor for a friend.

 

[Soopitup]

Your logic is flawed in many ways including your inference as to what what I an saying. I will make my meaning short and simple:

Helical thread repair inserts strengthen just about every application in which they are used including a mild carbon steel drain bung.

There are a myriad of reasons for that and they are well documented in the literature but I will give you four very basic ones:

1. An ordinary run of the mill STI has a tensile strength of 200-250 KSI, a Rockwell hardness of 45-50 RC, and a surface finish of 8-16 micro inches. That is far better than any parent metal tapped hole you are ever likely to encounter.
2. The major diameter of an STI is slightly larger than the major diameter of the original tapped hole. That means there is more parent metal area in shear and the pullout strength of the female thread in the parent metal is increased.
3. The shear and tensile strength of the STI internal thread is greater than the parent metal and since the area in shear of that thread form is the same as the original parent metal that means the internal thread is stronger than the original Additionally improved surface finish and hardness of the internal thread reduces the effects of galling and erosion during multiple assembly cycles..
4. The physical properties of the insert act as an isolator protecting the parent metal from the effects of fatigue.

That is why NASA and many ordinary OEMs frequently specify inserts rather than parent metal threads. It benefits their higher tech applications and it will benefit your lower tech ones as well.

If you simply don't like them and want to use an alternative repair that's up to you. But please do not misrepresent their performance to people that might actually choose to use and benefit from them. Hopefully the OP has not been run off by this train wreck and is now well informed as to his different repair options.

Dan

Dan, you're completely missing what I'm saying.
I'm not arguing about the strength of the metal in the helicoil or the effectiveness of a factory installed helicoil.
I'm arguing about the effectiveness of a field installed helicoil and the likelihood of it causing problems down the road, specifically in a steel oil pan.

Galling in a steel oil pan is basically moot. Regular steel isn't particularly susceptible to galling, and it has residual oil to lube it. I can't remember ever running into a galled steel drain plug.

The strength of the helicoil itself doesn't matter if the installation is flawed. There are many other failure possibilities than the helicoil itself breaking. If the thread they're inserted into isn't correct they have a tendency to deform and strech. Then the bolt won't thread in.
If they're not installed correctly the ends also have a tendency to unravel with use.
Then you have a threadlocked in helicoil you have to remove.
How out of round/oblong/misshapen do you think a hold hand drilled on your back with a cheap bit is?
Compared to a hole drilled with a machine in a factory using an expensive bit?
The hand drilled hole will probably be fine to install a regular bolt.
But a wound spring (your helicoil) that relies on it's ENTIRE length being supported by the thread it sits in, and needing to be firmly secured to that thread, is a different story.
How comfortable do you think NASA or an OEM would be using a helicoil installed that way?

I would appreciate it (Dan) if you'd address that last paragraph and let me know where you think I'm wrong.
Honestly.
I'm not interested in winning the argument, I'm interested in getting the right answer out there.

I've been a mechanic for 25 years. I had my ASE with L1. I've dealt real world with helicoils. I've installed them, and I've had to deal with numerous damaged ones.
My criticism isn't coming from theory, it's coming from real world experiences.

I'm also not arguing against using them. I've said MULTIPLE times they have their use. Even in this particular instance. There are just better options to try first.

 

[North Idaho Wolfman]

WOW, Guys enough is enough!
Take the bickering to a PM!

 

[TheOldHokie]

Dan, you're completely missing what I'm saying.
I'm not arguing about the strength of the metal in the helicoil or the effectiveness of a factory installed helicoil.
I'm arguing about the effectiveness of a field installed helicoil and the likelihood of it causing problems down the road, specifically in a steel oil pan.

Galling in a steel oil pan is basically moot. Regular steel isn't particularly susceptible to galling, and it has residual oil to lube it. I can't remember ever running into a galled steel drain plug.

The strength of the helicoil itself doesn't matter if the installation is flawed. There are many other failure possibilities than the helicoil itself breaking. If the thread they're inserted into isn't correct they have a tendency to deform and strech. Then the bolt won't thread in.
If they're not installed correctly the ends also have a tendency to unravel with use.
Then you have a threadlocked in helicoil you have to remove.
How out of round/oblong/misshapen do you think a hold hand drilled on your back with a cheap bit is?
Compared to a hole drilled with a machine in a factory using an expensive bit?
The hand drilled hole will probably be fine to install a regular bolt.
But a wound spring (your helicoil) that relies on it's ENTIRE length being supported by the thread it sits in, and needing to be firmly secured to that thread, is a different story.
How comfortable do you think NASA or an OEM would be using a helicoil installed that way?

I would appreciate it (Dan) if you'd address that last paragraph and let me know where you think I'm wrong.
Honestly.
I'm not interested in winning the argument, I'm interested in getting the right answer out there.

I've been a mechanic for 25 years. I had my ASE with L1. I've dealt real world with helicoils. I've installed them, and I've had to deal with numerous damaged ones.
My criticism isn't coming from theory, it's coming from real world experiences.

I'm also not arguing against using them. I've said MULTIPLE times they have their use. Even in this particular instance. There are just better options to try first.

I am not missing your point. You have an opinion about the reliability of STI repairs done by a shop and mine differs. Period.

Dan