If you are experiencing oil transfer from the transmission to the crankcase on your xc4 then it is likely you have a bad crankshaft seal. Seems the tolerances were off on the early ones and the seal could spin in the case or even pop out, letting oil get sucked unto the crankcase from the transmission.

In the US KTM have been taking care of this free of charge from what I have read. So option 1 should be to contact you dealer to see if they will take care of it.

If they say no, or if you are like me and will not let anyone else work on your bike, below are instructions for replacing the seal yourself.

First order of business it to get the supplies you will need.

The new crankshaft seal carries what I believe is the same part number as the original:• 07603547451 shaft seal ring

But as you can see from the pictures below the new seal is of a different design. The old one is on the left and the new one is on the right. Both are typical single-lip spring-seal designs but the old one has a plain metal casing where the new one is covered in rubber. So the old one was a steel to aluminum press fit in the case where the new one is a rubber to aluminum press fit. The new one is also taller meaning it totally fills the seat in the case and actually protrudes a mm or so when fully seated.

KTM recommend using a retaining compound when installing the new seal. You want three things here - a good cleaner to get the case as clean as possible, a primer, and a retaining compound. Below is a pic of the Loctite products I used. I chose 603 over the KTM recommended 648 based on greater tolerance to installing in an oily environment. If you get it really clean the 648 should be fine, but I went with the 603 just to be sure. Both have similar properties in terms of strength and operating temperatures. You can get this stuff from any decent industrial supply house.

You might also want to pick up two locking washers - one for the clutch hub and one for the balance shaft. You might get away with reusing them but they are cheap so it makes sense to just order new ones while you are ordering the seal. KTM part numbers are:

• 78033232000 tab washer• 77332018000 retaining plate

Now getting to the job... In summary you remove the kickstarter, right side cover, clutch, oil pump drive gear, oil pump cover, left side cover, balancer shaft, primary gear, and then at last the seal. Then replace the seal and button everything back up. A fair amount of work so allocate a few to several hours depending on your pace with mechanical work like this.

Get started by draining the transmission fluid, crankcase fluids, and the coolant. Pic below shows me pointing to the lower bolt on the water pump housing which acts as the coolant drain. Have a container ready as it shoots out quickly once you remove the bolt and the radiator cap.

Remove the kick start lever. Pic here mainly to pause and make two points:

• Use anti-seize on the splines when you reinstall to avoid having the lever fuse to the shaft in the future. It happens and is a pain to deal with.

• Clean the threads on the bolt and inside the shaft well and use blue Loctite when reinstalling. When my bike was relatively new I checked the bolt after a ride and it was about to fall out.

Now remove the right side cover. It helps to lay the bolts out in order so you can remember which goes where when you put the cover back on.

You now have a wonderful view of the right side of the engine.

Next tasks are to get a few components out of the way so that we can remove the primary gear. First is theclutch - pressure plate, clutch plates (keep them in order), spring washer behind the clutch plates (note it's orientation), the clutch drum (note the placement of the thrust washer behind it), and finally the clutch basket. Pic below shows the lock washer I recommended replacing earlier. The large nut is best removed with an impact wrench.

At this point you should locate the crank at TDC and lock it in place. KTM make this easy by providing a special bolt that mates with a notch in the crankshaft. First spin the crank until the dots on the primary gear and the balancer shaft are lined up.

Then go find the side cover bolt that has the large copper washer on it.

Remove the washer and set it aside, then install the bolt. It helps to rock the crank back and forth a few degrees until you feel the bolt mate with the groove in the crank.

Now remove the oil pump drive gear that is blocking the primary gear. It is held on with a c-clip and thereis a locating pin behind the gear, pull that out and set it aside.

Now remove the two bolts and the oil pump cover. No need to remove anything else here. Be sure to clean these threads well and use blue Loctite went reassembling.

Now you will see the only thing in the way of removing the primary gear is the balancer. Go around to theother side of the engine and remove the left side cover.

Then remove the nut on the end of the balancer shaft. The pic shows the other lock washer I recommended replacing earlier.

Now you can wiggle the weight off the left side of the balancer shaft and push the shaft through to the right side to remove it.

Almost there! Now remove the nut holding the primary gear in place. Note that is is left-hand threaded! When you reinstall this get the threads it very clean and use red Loctite. Wiggle the primary gear off and you will now see the crank seal that is the focus of all this work. Note I did not need a puller to remove the primary gear, it came off by hand, If yours is on there tight you should carefully use a gear puller, taking care not to mangle the end of the crank or any teeth on the gear.

There is no good way to grab the crank seal to remove it. My solution was to carefully and slowly drill a hole in the seal, taking great care to capture all of the metal shavings. I then inserted a sheet metal screw and used that as a handle to remove the seal. If you think of an easier way to do this post it up here to let everyone know.

That's about it for the how-to. Use the Loctite stuff mentioned earlier to clean, prime, and retain the new seal. Wipe a little grease on the seal lip to keep it from running dry on the crank when you first start it up. Do not be alarmed if the new seal protrudes about a mm from the case after it is fully bottomed. This did alarm me and I spent some time with calipers measuring all of the clearances. The seal face will be very close to the back of the primary gear assembly but will not interfere with it as long as you have the seal fully bottomed.

Then just put it all back together noting the areas you should use a threadlocker - primary gear nut, oil pump cover bolts, and kickstart lever bolt. Use new locking washers on the balancer shaft and clutch hub nuts, or be very careful if you are reusing the old ones.

Last but not least, here are the key torque values in case you do not have a shop manual:• primary gear nut, left-hand thread, 150Nm, red Loctite• balancer shaft nut, 40Nm• clutch drum nut, 80Nm

If you are somewhat absent-minded like me, set out your new transmission and engine fluids as well as coolant in an obvious place. That way you will not get so excited about being done that you forget to refilll before you restart the engine.

It would also be a good idea to let everything sit a few hours before firing it back up. That will ensure thatthe retaining compound on the seal has had time to set. The primer should help it set quickly, but waiting a few hours certainly will not hurt.