Stripped oil drain thread, options? (new pan/tap/...)

[roeme]

Hi all,

changed the oil recently on my bike, and had to discover that PO overtightened the oil drain screw, and stripped the oil pan's threads. I have now a temporary fix in place (teflon tape), but I'm not sure which route I should go regarding a permanent fix. I have currently these options in mind:

1. Tap a new thread, one size higher:
I have tapped a thread exactly once in my life so far. I don't know how to make sure I get the tap exactly perpendicular into the oil pan while its still mounted – I assume this is necessary, otherwise the drain screw won't seal properly. Or am I wrong? Is there some leeway or trick (Copper washer...)?

2. Replace the oil pan.
Would require me to take off the exhausts, which I'm not that keen to do on this bike, as there is another PO repair present at one of the exhaust collars (see pictures below).
Upside would be I could check the screen at the bottom in the same go, and clean if necessary.

I have a new oil pan (from a '77 550, IIRC these fit) & gasket ready, and can get a tap and fitting screw on relatively short notice, so economically there isn't much difference.

Tangentially:
a) Is there a torque specification on the oil drain screw? Or just "don't be stupid"?
b) Why did Suzuki decide to go with a weird pitch thread on the oil drain screw? I measure M14x1.25 ("regular" ISO would define M14x2 for coarse, M14x1.5 for fine). Vibration resistance? :-k


Now for some pictures to round off the call for education. Please ignore the dirt on the bike, I just don't have the time for aesthetics at the moment. Click the pictures to get full size.

Incontinence!

...that might not look like much here, but it's worse.

Lay down please. I don't want to change your oil all the time. Also, you like it that way, dontcha.


Hmmm, that's no Helicoil.




If you click through to full size, you can see a stripped thread in its natural habitat. Wait, these are unnatural, THEY HAVE NO BUSINESS THERE!
Also, funky FX because I got oil on my lens. Luckily, these phone cameras clean up easily.



INTERMISSION: Wound some teflon tape around the drain screw, and carefully screwed it back in – it has a tiny weeny bit of thread left where it can hold on. No pictures of that unfortunately, too immersed in work.

This picture has been taken after a ~20min ride home. It looks like the temporary fix holds up for the time being.


And this here is why I'm not keen on taking off the exhausts. Who knows how this PO fix will hold up to a remove/remount cycle?

 

[uk gs nut]

I would think you have 2 options, change the sump or get original repaired. Your going to have to remove sump anyway as you could damage the oil pickup strainer filter trying to tap for helical or timesert. Plenty sumps on eBay.

 

[Guest]

Hi.

I have not been on the forum in a century or two so new stuff could have come out.

But I beliebe back when the product most sugested was timesert repair kit.
Make sure you get the proper size,

Imagine a solid helicoil.

There plenty of vid on the net on how to.

Daniel

 

[Nessism]

In the other half dozen threads I can remember about stripped drain plug threads the brethren here typically recommended using an oversize drain plug. You can get them at an auto parts store and they have a tapered shape and are designed to cut their own threads in aluminum. Just get the 14mm type and crank them in.

 

[bobgroger]

14mmX1.25 is standard spark plug thread. Lots of options out there. I suggest taking the pan off to fix it no matter what you do....

 

[Nessism]

14mmX1.25 is standard spark plug thread. Lots of options out there. I suggest taking the pan off to fix it no matter what you do....

or not...if he was to use a self tapping oversize plug.

 

[roeme]

Thanks y'all.

Using an oversize plug is tempting, but first I have to find out where to get them around here. Almost nobody works on their cars here, so almost no specialised stores, and often only a small selection of parts available.

Or I'll just bite the bullet and remove the exhausts. I already did that to my other bike, but I needed to apply a lot of heat, took me a long time and a lot of cussing.

Are the sump screws all of the same length?

 

[Steve]

If you are willing to try the oversize plug, I can look into sending one to you.

Of course, the major expense will be shipping, as the plug itself is only a couple of dollars.

You will have to determine whether the shipping cost would be better than taking a chance on removing the exhaust.

.

 

[alke46]

Reach out to some of the other European members of this forum to find out if the oversized plug is available. Maybe then you can get one quicker and more reasonably priced. Good luck, I would definitely try the oversized plug 1st. Just my opinion.

 

[alke46]

Did you use the regular white Teflon tape? There is also a gas specific tape that is yellow in colour which might hold up the temporary fix better than the white tape.

 

[roeme]

I will add such a screw to my inventory in any case, and it's what I'll be trying first. If I can't source them locally, I will take you up on the offer, steve. Can't imagine the shipping costs too outlandish for such a small item.

Did you use the regular white Teflon tape? There is also a gas specific tape that is yellow in colour which might hold up the temporary fix better than the white tape.

Thanks for the hint! I did use the regular white, so far it holds up. I don't really ride the bike currently, because of both the weather and the lean condition to be fixed first, so I'm not too worried about it.

 

[SVSooke]

My 82 GPz750 came with a rubbery type oil plug thing because of stripped threads.I just bought a 14X1.5 car oil plug and tap off eBay cheap from China,less than $10.Original on that bike was 12x1.25 IIRC.

 

[bobgroger]

or not...if he was to use a self tapping oversize plug.

I searched online a good bit, found plenty of 14x1.5 but no 14x1.25. There is the "universal" expanding rubber plug but.....
Also found a couple old threads here, no luck finding one there either.

 

[Crankthat]

When it comes to your temp fix, glad you are not riding the bike at this time.
Likely it is ok, but...
If the plug did come out while you are riding.
Hope you notice it before leaning into a turn.

The oil will dump real quick.
Your dummy light should come on.
The first thing you would likely notice is the rear wheel slipping.

 

[Nessism]

In looking back through the archives in various other threads on this topic there are other guys recommending the 14mm x 1.5 self tapping drain plugs. The stock thread pitch size is 1.25 but since the threads are gone now that won't matter much. The self tapping plug is larger and will cut it's own threads. If you can find a 14x1.25 self tapper that would be even better but I can't find one. Lots of 14.1.5's on the market though.

 

[Agemax]

if the teflon tape makes for a leak tight fix then drill the sump plug and lock wire it on, that way it may work loose a tiny bit but it wont come out.
I would only use this as a temporary fix though until a more permanent solution is found.

 

[duaneage]

The torque on the plug is a mere 7 foot pounds. I use a torque wrench on mine and I don't exceed 7 ft pds.

 

[roeme]

I decided to change the oil pan, after testing that the exhausts and exhaust bolts aren't stuck.

They weren't, but you remember the PO bodge up there? Yeah, that has come back to not only bite my in the ass, but take a good chunk out of it. Separate thread will follow.

Anyway, bike on the side. All bolts were in good nick, no corrosion whatsoever. A pleasant change, for once.


Some crappy oil...


...and the remainer of the thread.


Screen looks good to my untrained eye, only minor crap on it (was old oil)


Took it out, cleaned up nicely and easily. New oil pan back on:


Cleaned the pipes for a bit as well. Impromptu "drying rack" made work a bit easier:


Had to discover a hole. But at least that looks patchable...


So the drain screw's good again, but I got new problems. *sigh* Will link in the new thread.

 

[roeme]

Here's the thread about the PO bodge. Clicky.