Help, split casing, drain plug

[mike-evans]

Did a gearoil change on my 01 yz 250 2t last week and went out riding yesterday, 10 minutes before i got picked up by my mate i noticed a drip of oil on the drain plug, closer inspection and noticed where the drain plug screws into the casing, one side is solid and wouldnt split and the other side of the threaded hole has got a thin wal and has slightly split probably due to being overtightened and is seeping gearoil :( anyone know how i can repair it in situ without replacing casing? One option i suppose is alu welding..? As i was short of time yesterday i mixed some chemical metal up and pasted that on the split so i could stil ride whilst monitoring the leak, i havnt drained the oil yet to see how much is stil in there?

 

[motometal]

short term/lower level fix is using something like JB weld, it the problem is in the threads you will need a tap.

A better way would be have it welded, then re tap the threads.

I think this could be fixed without splitting cases. Remember if you weld and do any finish work on the weld, don't get any grinding wheel debris inside. Obviously you are trying to avoid getting any foreign matter in there, but a few flakes of aluminum from a fluted cutting tool aren't likely to hurt much compared to grinding wheel debris.

 

[mike-evans]

i think a product like JB weld would seal up the split, but i dont know how long it wil last as when i remove and refit the drain plug it wil possibly make the split worse? I think best would be to scrape the split so i create a V shape in the split and get a alu welder to fil the split chanel with weld and then if needed run a tap through it, without checking the manual i think its a M10 tap, if so i have a set at the ready.....

 

[Rich Rohrich]

You have to split the cases, clean the cases so the area to weld is completely oil free and so SPOTLESS you could eat off it. Then you'll need to pre-heat the case to somewhere in the 350F range, and then (and only then) you'll have a chance of producing an aluminum weld on both sides of the case where the crack sits. If you want it to last, it takes doing it correctly.

Trying to weld it in the frame from the end point of the crack is a waste of time and effort. JB Weld will work just as well as a dodgy aluminum weld, and is much easier to accomplish.

 

[Uchytil]

There's a good chance the crack will grow. A welder will drill a small hole at the termination point of the crack. I've used magnaflux spray (3-part) that penetrates the crack to highlight the exact end. The small hole will keep the crack from creeping. Good luck.

 

[mike-evans]

wel put around 750-770ml in the gerbox last week and done a bit of riding on Saturday then dropped the oil, i got around 750-760ml out, so it doesnt seem to be losing alot? I used a liquid metal type paste and put that around the split and let it go hare...I put around 750-770ml back in around 4o'clock this evening and checked it 10 mins ago (5 hours later) and the clean bowl i put under the drain bolt to check for drips had probably one or two drips of gearoil in it and a little around the drain bolt, so i think if i monitor it regulary i should be ok with it? Its a pain not having a sight glass or level check bolt on the 250 2t yams.. :(