[hydnawaab]

I have a 2016 Classic 500 and my main oil drain thread is stripped. As per service tech he tried a few things but the oil is still leaking. He is recommending to completely seal off the drain as there are two other drains and they can be used to drain the oil. Please advise if it is ok to do so.

[heloego]

Had he considered re-threading with a Helicoil?

[mattsz]

If the sump threads really are ruined... what about one of those slightly oversized, self-threading plugs that CMW used to sell?  I have an unused one going spare...

[hydnawaab]

Had he considered re-threading with a Helicoil?

Yes he did and it is still leaking. Can he permanently seal the main drain and use the other two drain holes to drain the oil when needed? Will that be ok? I just don't want the the plug come off in motion where the tire will slip on freeway.

[hydnawaab]

If the sump threads really are ruined... what about one of those slightly oversized, self-threading plugs that CMW used to sell?  I have an unused one going spare...

Not sure how much room I will have to create new threads. In other words I dont know how think the metal is and that is why I was thinking about permanently sealing if this drain is not needed. Can we drain the oil with the other two drains?

[mattsz]

Yes he did and it is still leaking.

That sounds strange - if it's properly helicoiled, and the plug is correct, it shouldn't be leaking.  Are you sure it's leaking from the drain plug?

If it's been helicoiled, I don't think the new oversized plug would work.  It's only very slightly oversized, and I think it's meant to cut into the original soft aluminum of the sump - which wouldn't be available with the helicoil in place.

Can he permanently seal the main drain and use the other two drain holes to drain the oil when needed? Will that be ok? I just don't want the the plug come off in motion where the tire will slip on freeway.

Yes, I see we haven't actually answered your question.

Don't do anything based on my input - hopefully the smart guys here will come by to give you a proper answer!  But... in my fairly unformed opinion: it's not ideal, but you could block off that drain if you had to.  Here's why: I assume the "other two drain holes" you refer to are the screen access hole, and the crank chamber drain plug - the latter of which the early UCE's didn't even have.  You'd leave a little bit of oil in the area above the primary drain plug, of course, but a lot less than early owners would leave in the crank chamber!

Here's a wordy post on oil draining I started awhile back, with lots of pics of the engine interior - it might be interesting for you to take a look to see (and read about) where the oil goes, and see the relatively small space above the primary drain plug which would actually hold oil if you sealed it.  You can easily see where the original drain plug and the screen access opening are situated from the inside.  It would take just a few minutes to read...

https://forum.classicmotorworks.com/index.php/topic,21436.msg239980.html#msg239980

[hydnawaab]

That sounds strange - if it's properly helicoiled, and the plug is correct, it shouldn't be leaking.  Are you sure it's leaking from the drain plug?

If it's been helicoiled, I don't think the new oversized plug would work.  It's only very slightly oversized, and I think it's meant to cut into the original soft aluminum of the sump - which wouldn't be available with the helicoil in place.

Yes, I see we haven't actually answered your question.

Don't do anything based on my input - hopefully the smart guys here will come by to give you a proper answer!  But... in my fairly unformed opinion: it's not ideal, but you could block off that drain if you had to.  Here's why: I assume the "other two drain holes" you refer to are the screen access hole, and the crank chamber drain plug - the latter of which the early UCE's didn't even have.  You'd leave a little bit of oil in the area above the primary drain plug, of course, but a lot less than early owners would leave in the crank chamber!

Here's a wordy post on oil draining I started awhile back, with lots of pics of the engine interior - it might be interesting for you to take a look to see (and read about) where the oil goes, and see the relatively small space above the primary drain plug which would actually hold oil if you sealed it.  You can easily see where the original drain plug and the screen access opening are situated from the inside.  It would take just a few minutes to read...

https://forum.classicmotorworks.com/index.php/topic,21436.msg239980.html#msg239980

Thank you for the nice reference. One last clarification; the screen mesh is not as part of the main drain plug correct?

[hpwaco]

Used to be able to buy expanding rubber drain plugs in various sizes at auto parts stores.   I used one successfully on a Honda 350 4  back in the 90's.    Maybe they are still available.   Cheers

[mattsz]

Thank you for the nice reference. One last clarification; the screen mesh is not as part of the main drain plug correct?

Correct.  The screen is forward of the main plug; it's got a cover with two small bolts holding it in place.  Here's an old pic from singhg5 - main plug lower left, screen cover just above that, and the newer crankshaft cavity drain to the right: