[mazzla]

Hi guys and girls. I got myself in a bit of trouble this weekend - went to change the oil in my newly bought KTM EXC-F 250 ('06), took the sump plug out, drained the old oil, but cannot re-install the plug. I think the outer (the very last) ring of thread in the engine case (there's no sump casing) is damaged, so that ring of thread on the oil drain bolt is not catching. The thread on the bolt and the rest of the thread in the engine is fine. There's very little space between the oil drain hole and the frame on this bike - just about enough to get the bolt out, so there's no way any tool that would re-cut that first ring of thread would fit in there. Is there anything I can do to get that bolt in - I don't want to have the bike sitting there dry for any length of time - I don't have a garage?

 

[dpapavas]

Try posting a well-focused, detailed photo of the threads. It'll help people make more informed suggestions.

 

[mazzla]

Try posting a well-focused, detailed photo of the threads. It'll help people make more informed suggestions.

Fair enough. Trouble is - I am in work all day and by the time I get home it is too dark to get under the bike and take pictures... I guess it will have to wait until the weekend.

 

[mazzla]

Try posting a well-focused, detailed photo of the threads. It'll help people make more informed suggestions.

Here you go - I hope this helps. Hard to get the shot of entire thread because of where the frame sits close to the drain hole... You should be bale to see the damage on the right.

 

[dpapavas]

Hmmm, that looks bad... I wonder if there's a reliable way to clear the damaged part of the threads out of the way, so that the plug can engage in the part that's intact. As most of it is intact, I suppose it could take the tightening torque without problems (perhaps somewhat reduced just to be on the safe side), but I don't have enough hands-on experience to suggest any definite method.

One idea, if it's physically possible, might be to pull the oil pan, and screw the plug, or a longer bolt of the same thread from the other side, hoping that it will restore the damaged threads enough to allow the plug to get past them, when it's screwed in the right way. I don't suggest trying it though, unless someone more experienced confirms it isn't nonsense.

 

[mazzla]

Hmmm, that looks bad... I wonder if there's a reliable way to clear the damaged part of the threads out of the way, so that the plug can engage in the part that's intact. As most of it is intact, I suppose it could take the tightening torque without problems (perhaps somewhat reduced just to be on the safe side), but I don't have enough hands-on experience to suggest any definite method.

One idea, if it's physically possible, might be to pull the oil pan, and screw the plug, or a longer bolt of the same thread from the other side, hoping that it will restore the damaged threads enough to allow the plug to get past them, when it's screwed in the right way. I don't suggest trying it though, unless someone more experienced confirms it isn't nonsense.

Cheers fella. The problem with this particular bike is that there's no sump/oil pan - it's a part of the engine casing. Not only that, the drain hole is ~4cm from the frame (not easy to see in the pictures), so it will be impossible to get a drill bit to remove the start of the thread. I think I may have to get the bike to a workshop in the end and get the engine out... I really didn't expect such odd design from the Austrians (albeit there's a fair share of my fault in it too)

 

[Ironhead401]

Cheers fella. The problem with this particular bike is that there's no sump/oil pan - it's a part of the engine casing. Not only that, the drain hole is ~4cm from the frame (not easy to see in the pictures), so it will be impossible to get a drill bit to remove the start of the thread. I think I may have to get the bike to a workshop in the end and get the engine out... I really didn't expect such odd design from the Austrians (albeit there's a fair share of my fault in it too)

Can you get at it with a right angle drill?

 

[grtfast]

Can you start a tap in it by hand, then turn the tap with a small wrench?

 

[charliev68]

Have you tried chasing the drain plug threads first.

 

[RaiderGT]

Buy a bolt of the same pitch/diameter. Put it in a vise. Take a dremel tool and cut two grooves lengthwise down the bolt. Bevel the end of the bolt. Run this through the drain hole with some cutting fluid or penetrating oil.

 

[Ironhead401]

Buy a bolt of the same pitch/diameter. Put it in a vise. Take a dremel tool and cut two grooves lengthwise down the bolt. Bevel the end of the bolt. Run this through the drain hole with some cutting fluid or penetrating oil.

Interesting. What do the 2 grooves do? Are you basically using the bolt to tap the hole a little or smooth out the damaged threads?

 

[RaiderGT]

Interesting. What do the 2 grooves do? Are you basically using the bolt to tap the hole a little or smooth out the damaged threads?

It essentially acts as a less aggressive tap. The grooves are a cutting surface and channel for debri. The trick is to make it as nice as possible. Does a great job of cleaning threads out and deburring, especially in places where a regular tap wont fit or you don't want to make the hole bigger. Old mechanics trick.

 

[mazzla]

It essentially acts as a less aggressive tap. The grooves are a cutting surface and channel for debri. The trick is to make it as nice as possible. Does a great job of cleaning threads out and deburring, especially in places where a regular tap wont fit or you don't want to make the hole bigger. Old mechanics trick.

Struggled with it for the whole weekend, but in the end decided to let the professionals do the job - [apparently] they will have to drop the engine out of it, access to the drain hole is really tight against the frame, nothing longer than the sump plug fits in there. Dumb design and dumb me for messing it up... Cheers for the responses though.