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2003 YZ250 broken off oil drain thread section from crank case, pics included

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Without the long story, I have a 2003 YZ250, overtightened the Drain plug and instead of stripping the threads the outside section of the plug hole cracked off of the transfer case.

First of all, this seems like a crapp design having the whole at a 45 degree angle with half of the threads protruding from the crank case. All bikes i have had in the past have been perpendicular(ive had this bike for 1 week not :applause:

My options seem to be purely replacing the crank case. Since shops are closed today i would speculate parts + labor on this would be around 500ish? Anyone have a better estimate?

Here is my first plan of attack. If anyone has seen this before or has and pointers PLEASE let me know.

I plan to use JB weld to attempt to patch this!

#1 thoroughly clean area

#2 glue together the two broken seconds. Apply thin second and third coats over the outside around the crack over th enext few days.

#3: glue this section to the main body. Over the next couple weeks apply many coats of jb weld in successively larger areas. I plan to do around 6 thin coats. Maybe one thick one at the end.

#4 Retap the hole.

#5 Use oil resistent gasket sealer on the top half of the threads and lightly screw this in with maybe 1/2 a wrench turn after finger tightening. I plan to use the gasket sealer as a weak form of locktight + sealent. Hopefully this will keep the bolt in place and allow for removal without damaging the hole.

I hope this "patch" job will work as there are no real high pressures in the crankcase. Its basic purpose is a plug.

Wish me luck, if anyone else has experienced this or has any tips or comments or predictions of failure let me know!

bike1.jpg

bike2.jpg

bike3.jpg

bike4.jpg

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I would talk to a welder and ask if some kind of bung can be welded on to the case. You could gring the rest off so you have a flat even surface to weld to and then tread a bolt into the bung with some teflon tape or you could use JB weld and hope it dosent crank off when it gets hot:confused:

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I'm sorry to say, with peices that big that fell off, even with the patch, it's going to start to leak. I wish you luck. The thing about oil, when it gets hot, it will find the smallest cracks and go right through them.

Little Jeff

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unfortunately i think that will probably be the case.

On the other hand it will cost me 5$ for jb weld and some permantex black oil resistant gasket sealer.

combined and covering the area with both i hope to atleast keep it from leaking for 6 months or so! Im just afraid of it busting or falling off. I can deal a tiny drip here or there.

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unfortunately i think that will probably be the case.

On the other hand it will cost me 5$ for jb weld and some permantex black oil resistant gasket sealer.

combined and covering the area with both i hope to atleast keep it from leaking for 6 months or so! Im just afraid of it busting or falling off. I can deal a tiny drip here or there.

good luck keep us updated on the results.

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the case alone is 500$ w/o tax and probably a few hours labor at the shop..., try the jb weld!

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Now it sounds like the real question is:

Should i completely JB weld the peices in place and then weld the BOLT in place also. Then continue adding coats and layers making the entire thing basically a block of weld. This would be completely strong and id assume a permanent fix although i would forever be flipping my bike over to drain the oil!

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if you are going the jb weld route.. you might be better off grinding the case down flat. then "welding" a nut in place. that way the threads themselves are solid. i have a feeling that lining the chunks back up to get the threads perfect might be kinda tough, and every time you take the bolt out you run the risk of it just cracking. i say grind the other piece off of there so the nut lays flat on the case, and then put a nice bead around the edge, maybe even under the nut where you press it to the case.

there shouldnt really be too much heat there so i wouldnt worry about the jb weld melting, and as for it leaking... i sealed up a couple cracks in a radiator with jb weld a while back... havent seen a drop of water come through it yet.

sure this might be the "redneck" way of fixing a bike, but hell, its already busted, it cant make it worse.. (assuming of course you dont drop all the oil out while riding and blow up the tranny from lack of lubrication... :applause: )

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I would split the cases, take it to a welder and get him/her to completely build up the entire orifice and then redrill it, mill the top flat then retapp it.

Do the job properly the first time.

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Current plan of action:

1: bring to expert welder for his opinion and hopefully weld the peices together while still attached to bike. Retap, use ample permatex black gasket seal on the screw.

if he cannot do this I will try the JB weld patch job and hope that holds for 6 months until I buy a house and have ample time and room to tear it down.

note: i am not a hard core mxer i wont be riding that hard.. probably twice a month. I have still yes to get major air off a jump. Im more of a trails rider or was

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Now it sounds like the real question is:

Should i completely JB weld the peices in place and then weld the BOLT in place also. Then continue adding coats and layers making the entire thing basically a block of weld. This would be completely strong and id assume a permanent fix although i would forever be flipping my bike over to drain the oil!

Ya remove clutch cover and place on side, the economical solution.

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Current plan of action:

1: bring to expert welder for his opinion and hopefully weld the peices together while still attached to bike. Retap, use ample permatex black gasket seal on the screw.

if he cannot do this I will try the JB weld patch job and hope that holds for 6 months until I buy a house and have ample time and room to tear it down.

note: i am not a hard core mxer i wont be riding that hard.. probably twice a month. I have still yes to get major air off a jump. Im more of a trails rider or was

Please post what the welder has to say. Im interested if he can handle it or not. I had it done on a VW crank case once and it wasnt pretty but held fine.

good luck:thumbsup:

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Now it sounds like the real question is:

Should i completely JB weld the peices in place and then weld the BOLT in place also. Then continue adding coats and layers making the entire thing basically a block of weld. This would be completely strong and id assume a permanent fix although i would forever be flipping my bike over to drain the oil!

You can't do this because the bolt is steel, and the cases are aluminum, unless you just had the hole plug welded.

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You might think about taking a burr and grinding the rest of the raised portion off. then take a 1"x1"by.500 (or however thick you want) piece of aluminum stock and drilling a hole in the center to fit a new drain plug, then have that piece welded to the crankcase over the old drain plug hole. If you do this make sure you drill the hole in the new piece with a drill press so that it is straight in to assure that the drain plug gasket fits flat. This shouldnt cost too much and you get away from the constant heating (expansion) and cooling (contraction) of the JB weld joint, which I'm not sure will last long. I'm not too concerned about a few drops of oil leaking, but of a failure where the whole thing cracks off and you dump all the oil. It should be easy for someone to weld around 4 sides of a block of aluminum. good luck:ride:

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Go to your auto parts store and buy a universal transmission drain plug kit I think MR Gasket makes it should work as long as you grind the rest of the broke piece off.It looks like a nut and bolt but the bolt is hollow and there is a plug in the center. You pinch the 2 togther on each side of the case with nylon washers.

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I've had this happen on my 91, it was perpindicular though. I JB welded it on and changed the oil from the side of the case. It leaked a little, but nothing too bad.

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Expert welder says:

"aluminum is very porous and soaks up oil. He would only weld it if i tool it apart soaked it and guaranteed there was no oil left in the metal."

current plan:

JW weld it!, about 3-4 coats and cover the entire bolt/area with permatex gasket sesaler, hope for 0 leaks

ill check out that uvinersal drain plug kit but that would still involve tearing the entire case apart.

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Expert welder says:

"aluminum is very porous and soaks up oil. He would only weld it if i tool it apart soaked it and guaranteed there was no oil left in the metal."

current plan:

JW weld it!, about 3-4 coats and cover the entire bolt/area with permatex gasket sesaler, hope for 0 leaks

ill check out that uvinersal drain plug kit but that would still involve tearing the entire case apart.

good plan, unless ur gonna sell it anytime soon. u could grind it down then weld some thick metal around it and drill out a new hole and put a new bolt in it. but if ur lookin at more than 500$ for the crankcase option

im having a somewhat similar problem right now, i feel your pain

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