ASK THE MXPERTS: “I MESSED UP MY 450SXF DRAIN BOLT”

The single most important piece of this drain bolt is the copper washer.

“I MESSED UP MY 450SXF DRAIN BOLT”

Dear MXA,
I replaced the oil in my 2017 KTM 450SXF, but when I got the job done, it leaked oil out of the drain plug on the side of the engine. So, I drained it again, but this time I cross-threaded the drain-plug bolt. Now I have wrecked the threads. What can I do to fix this?

First, you need to understand how this happened. We’d guess that when you pulled the drain plug out to change the oil, you failed to notice that the copper drain-bolt washer fell off. Then, when you reinstalled the drain bolt (sans copper washer), it threaded into the engine cases too far (since the copper washer is used to achieve the desired length of the drain bolt). Without the copper washer, the tapered and unthreaded shaft of the drain bolt rolled the first threads on the engine cases over. When this happens, the bolt will feel cross-threaded when you try to take it out or put it in the engine cases.

Since you kept trying to put the drain bolt in, you messed up the threads on your cases and probably the threads on the drain bolt. All of this happened because you lost the $2.95 copper washer. You’re lucky that you did this on a KTM 450SXF, which has an easily accessible drain bolt (below the shift lever). If you did it on a 250SXF or 350SXF, you would find that you can’t access the drain-bolt hole to chase the threads without removing the engine from the frame. The best solution is to clean up the threads in the cases with a tap to make sure that the first threads will allow a new bolt to get started—and you will need a new drain bolt and copper washer.

If you don’t have a tap-and-die set to chase the threads, the backyard fix is to take a new drain bolt and carefully start it into the drain-bolt hole. This shade-tree repair can be done on the 250SXF, 350SXF and 450SXF without any fancy tools. You must make sure that you have the drain bolt properly aligned. Once you are sure that it will thread into the drain hole in a straight line, thread the new bolt in and out slowly, using the new bolt to clean up the threads that are damaged in the cases. Only the first couple threads were damaged by the tapered shaft of the drain bolt (when it went in past the end of the threads because the copper washer was missing). Once you have the threads cleaned up, gently tighten the new drain bolt and copper washer. Don’t overdo the tightening.

 

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