Cracked Case Around Drain Plug.

[biglou]

Here is a picture of my buddy's 99RM250 drain plug area. There are two problems. 1) The case is cracked, and 2) The threads are all but gone. Here is my plan, just wanted to see how many of you concur:

I have stop-drilled the crack with a 1/8" bit to a depth of about 1/8". My plan is to grind a groove following the crack (including the bolt head seating surface) and then heli-arc it and then grind/polish it down, taking extra care to get the bolt head seat area flat enough for the copper washer to seal.

Secondly, I intend on heli-coiling the drain hole. I have one question-Does the heli-coiled hole accept the same drain plug thread size as before the repair? Just curious because we have a brand new magnetic drain plug to install.

So, does my process sound reasonable? There's no getting around having to heli-arc that crack. This thing was leaking badly.

Here's a close-up of the crack:

 

[XRpredator]

JB Weld, my good man! ;)

Actually, I think you can get a heli-coil the size to fit the drain plug, and it'll tell you what size bit to use to get it to fit right. The kits are pretty self explainatory. Done it many times, I tell you what.

 

[jmics19067]

helicoils come in standard thread sizes so if you drain plug is a standard bolt size a helicoil will work with the plug. What you have to do is to buy a special tap for that helicoil. They come in nice little kits tap , installation tool and a couple of helicoils and you can buy helicoils seperately. I suggest the kits. Since it is a relatively big bolt it might be a little pricey.

 

[bscottr]

Originally posted by BigLou
I have stop-drilled the crack with a 1/8" bit to a depth of about 1/8".

Lou,
I'm latching on to this one if you don't mind.

The only concern I have is with not drilling completely through the case to prevent the crack from continuing on the inside, away from the future weld. In other words the crack could be deeper than the 1/8" depth.

Good Luck,
Scott

 

[biglou]

I'm debating about that myself, Scott. I figure that we're gonna cover it with weld anyway. I'll run that by my head machinist tomorrow before I bore all the way through, but I am leaning that way.

 

[IrishEKU]

Hey Lou,
Heli coils are nice and conveinent. Problem is they back out from time to time. My experiance(In the ARMY and it is by no means EXPERT!) is that they back out at the most unopertune times! Here is what I would do............Weld his case up.......Solidly.........Buy a tap.....For the original thread and run it up through.......That will clear any burring and slag from the weld.Then run the next size tap up through with the same thread gap........That way you remove the risk of leakage...........When you set the new plug(Same size as the over size tap!) ( not for you ......the explaination is for otheres that want to try the same repair) and throw in a Crush Washer...........You know the type, made of copper and a fiber filling. Cinch it down to the original tourque settings or for those SHADETREE"S out there..........."German tourque"(Gut EN Tight) and the problem is solved!
PK

 

[bscottr]

Lou,
Is this the result of over torque? :(

 

[biglou]

Not sure. Bought the bike used about 10 months ago. We got the topend kit that Suzy gives with their bikes but neglegted to put it in this winter (big mistake). Ate a piston a few weeks ago and cost him a bottom end too. Then, just a week or so ago, he started getting a huge amount of oil leaking. I figured he just accidentally lost the copper washer (done that myself on the ktm). But, alas, we find this crack, so we have to yank the motor again. The only good part is that we're pretty fast at it now! And after our top/bottom end rebuild, it fired on the second kick. Then he rode half a lap and cased a double breaking both ankles. I know, it sounds pretty pathetic!

 

[motomad]

Have to go with Scott,BigLou. IMHO if you leave any crack in something that vibrates as much as a 250 single,we'll all be meeting here again in a few months. Have you figured out a way to index it in order to face the bearing surface? Might not be easy.

 

[biglou]

Not really. Unfortunately, I am planning on using my "calibrated eyeball" and hoping for the best with some tolerances with regards to the copper washer. I'll post pics when I get it all sorted out. If it still leaks, well, I guess we're going into the case again. That one will cost big, too. :(

 

[yzeater]

So this guy is in a wheelchair and you're working on his bike?

 

[bwalker]

Lou, I would use a product called Timesert to fix the threads. They are stronger and more durable than Helicoil. I think they can be ordered from J&L industrial supply. I would also drill all the way through unless it is not possible.

 

[bscottr]

Originally posted by BigLou
Then he rode half a lap and cased a double breaking both ankles. I know, it sounds pretty pathetic!

Ouch! :ugg: How's he doing?

Lou,
I understand Eric and Rich have mucho experience here, you may want to PM them.

 

[biglou]

Sunday was his first ride after the incident. He's OK. Got glass ankles, though. Not the first time that happened.

Ben-I will drill all the way through. I'm at work now and am getting ready to start this thing. I'll take pictures as I go along and post here.

It will either be poetry in motion, or one expensive hunk of mldern art masterpiece within a couple of hours. (Fingers crossed!)

 

[biglou]

Well, I am told by my machnist that the heli-arc temp will melt the internal seals and the case gaskets near the welding area. So, I am going to drill it through, then grind a groove in the crack and let her have some JB Weld. That only leaves us with the thread issue. I hope those will hold long enough so we can put it back together and get some riding out of it. I'll look for a time-sert in metric and get it on order. We can do that part on the bike. Kinda need it back together for Saturday night racing. We gotta get out there and stink up that 250 beginner class!

 

[RM_guy]

Lou,
Is the thread a M12? If so, you can run a 1/2 fine thread tap in the hole but you'll need to make your own plug out of a bolt. Also if you are just using JB weld, add some gasket sealer to the threads when ever you reinstall the plug to help seal up the crack better.

Good luck

 

[motomad]

:eekSix words,Lou. Safety wire.....safety wire.............safety wire.

 

[Ol'89r]

Lou.

May I offer a suggestion. Check with some of your local bike shops to see if anyone has a heli-arc welder and some experience with fixing drain holes.

I have repaired quite a few myself and if properly done, it can be welded without damaging the gaskets.

Clean the area very good and then grind a deep vee in the crack. Go almost all the way through the case with the vee. Dont worry about drilling the end of the crack. A good welder will be able to wash the crack out into good metal. The welder will be able to fill the vee'd out section of the crack without using too much heat. If you don't vee it out it will take a lot more heat to weld the crack all the way through and it could overheat the gasket.

Prior to welding, clamp the crack back together. Notice that the crack is spread open at the bottom a little. Have the welder either weld the hole up using a rosett weld and then drill it out and tap it. Or just weld the crack and heli-coil it. A spot facing tool will work to re-machine the sealing surface.

The thing that causes this to happen is a two dollar sealing washer. Never re-use the drain plug washer. When you keep using the same washer, it crushes the washer and forces it down into the drain hole in the middle. This acts like a wedge and over time will split the hole open. This is especially true with aluminum drain washers. If you use a new washer each time, this won't happen.

Also, when removing the drain plug, take a small hammer and strike the drain plug before trying to loosen it. This makes it easier to loosen it.

Just my $ .02.

Ol'89r

 

[jmics19067]

The epoxy will only be a temporary fix and I dont believe you will ever really get a good seal using it. How temporary and how much of a seal is directly related to how much preparation you start off with. But hey if it lasts long enough so you are not getting bent out of shape from always epoxying. It is lasting longenough right!

I am thinking that the crack is all the way thru to the threads and thru the sealing area. So I am kinda thinking that maybe you should get a flat washer and glue that to the sealing area with the epoxy. Hopefully giving you a decent sealing surface for your copper/fiber washer. After all is perfectly cleaned , schmear your epoxy, place flat washer in its place and using the old drain plug lightly oiled<to keep epoxy from sticking> and run it in until it is flat against the washer . Just an off the top of the head idea that I think I would try. Dont bother heli coiling it thinking that it will help seal it wont!
hey just had a brain drizzle if you have a machine shop make you a T shaped sleeve that threads into the case with a machined surface for your gasket and a threaded hole for a your drain plug , glue that in. How much material in the crancase boss you would have to remove and how small of a drain plug would be suspect though.

 

[biglou]

Well, the JB Weld is setting as we speak. 89'er, this was a budget job for a friend. I know, we're cheap, but it's not mine and I wasn't going to pay for it. I got the V ground in and filled her with JBW. After much searching for an M12 x 1.25 thread repair kit, I found a 1/2-20 magnetic drain plug at NAPA for $3! (3.19 w/tax:D) So, after the weld cures, I'll tap it out slightly oversize and use the new drain plug. Thanks for that info, RMGuy!

I'll get some picks of the hack-job up here in a few minutes.

Thanks for all the help, everyone. :)

 

[XRpredator]

Gonna have to change the sig from Carpe Ducto to Carpe Iota Beta! (seize the JB -- no Greek J, sad to say :confused: )

 

[bclapham]

this makes great reading watching the repair unfold live!

i had a similar problem on a fuel injetor insert on my old VW. i drilled the crack and used devcon expoxy, after curing i re inserted the insert and sealed it with thread lock (it was a permenant fixture). but after only a few miles, the crack leaked and the car began to smoke like the batmobile. i think that the main problem is getting the surface free from contamination, since it is the oil drain hole there is so much oil left around to cause the JB not to stick.

but i have had more success fixing a clutch case using the devcon, since we could take it off the engine we managed to get it really clean and dry (in a cool oven) before adding the epoxy. after a 1 day cure we then put it back in the oven for a couple of hours to get a really good cure.

good luck, i hope you prove me wrong, but i think this ight turn out to be only a temporary fix

 

[biglou]

I hope to prove you wrong, too! I know it looks dirty in the near vicinity of this fix, but rest assured, I cleaned it very well. I used a super-secret industrial mold cleaner (as in forming mold, not mildew) that leaves no residue to clean the area off. Here is one view of the finished job. The drain bolt is only snugged up with fingers until tomorrow when the epoxy cures fully.

 

[biglou]

One more view:

 

[RM_guy]

Originally posted by RM_guy
... Also if you are just using JB weld, add some gasket sealer to the threads when ever you reinstall the plug to help seal up the crack better...

Don't forget to smear the threads with some gasket sealer. It doesn't matter what kind, even silicone will work, since you can reapply it after every oil change.