Stripped Drain plug

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Paul1972

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I have managed to stupidly stip the thread on the small drain plug on my Mk 2a. I'm pretty sure its a 9/16 A/F ? Would a heli coil be the best solution and would they do this size? Thanks
 
Paul, check with Old Britts, tab on the technical article and look on the engines. There is a thread on a fixing stripped drain plug. Jerry
 
The old britts way is what SHOULD be done but it's not at all practical unless you have the engine apart anyway. Auto parts stores have all sorts of fixes for this; one of them should work on the bike just fine.

You could helicoil it as it sits - I have done helicoils in much more difficult positions BUT, of course, in this case you are drilling/tapping in the crankcase and some AL shavings are going to end up in there. I can't think of any way to ensure that doesn't happen but it might be possible with some thought and a lot of care...
 
mike996 said:
The old britts way is what SHOULD be done but it's not at all practical unless you have the engine apart anyway. Auto parts stores have all sorts of fixes for this; one of them should work on the bike just fine.

You could helicoil it as it sits - I have done helicoils in much more difficult positions BUT, of course, in this case you are drilling/tapping in the crankcase and some AL shavings are going to end up in there. I can't think of any way to ensure that doesn't happen but it might be possible with some thought and a lot of care...
Click to expand...

This might be risky, but drill, rethread, plug and then fill the sump with oil (*some* Nortons do this by themselves :wink: ) and let it drain. That should get out all/most of the shavings. We won't talk about if warm oil flows better than cold oil. :roll:
 
Had the same many years ago. Helicoiled in situ. To get rid of any swarf caught inside the crankcase, remove the big drain plug / filter bung. Get a funnel and fit a hose onto the spout. Shove the hose up inside the filter bung hole, wrap a rag around the entry and hold it there. Put a shallow wash tray underneath. Get the missus or other useful creature to pour a pint or so of diesel of kerosine into the funnel. Pull the hose and let the rinse wash out. Check for metal particles. Messy but works.

Mick
 
Hortons Norton said:
Grease is the secret.
Click to expand...

Amen.

Done it in situ. Leaned the bike on its side, and used LOTS of grease on the drill bit, working very slowly. No problem. Helicoil, or Recoil did the trick.
 
Also on the tap too, I was wondering if anyone had heard of this before. It's and old trick passed on to me a while back. :wink:
 
Thanks for the advice guys, I did hope there would be a way without taking the engine out. I will let you know how it goes.
 
Uh-oh...did they used to make heli-coils out of cheesy aluminum in the '70's?

Stripped Drain plug
 
pantah_good said:
Uh-oh...did they used to make heli-coils out of cheesy aluminum in the '70's?

Stripped Drain plug
Click to expand...

Man, I've seen that too many times. As a kid I worked in a shop where the boss was taking care of his drug addled nephew. He was put to work changing oil and tires. The typical drain plug pack in those days had a huge hex on it but the plug was only threaded into a thin piece of sheet metal on the inside of the pan. Sandy would grab the huge wrench that fit it and strip them out repeatedly. We finally cut a bunch of wrenches down to 6" to stop it. His brain was just too softened to ever get it and he couldn't be fired.

It's a little different than an aluminum crankcase but normally we just drilled and tapped them to an oversize in place and rinsed the sump out with gasoline, got some other interesting stuff out not related to the machining. I would not hesitate to helicoil in place with grease on the bit and tap and a rinse out for good luck.
 
Grease on the drill and tap will stop most swaf gertting into your motor, do it slowly and all will be good, this is a old trick that a lot of old tradies do without pulling a motor down, being a T/A to a maintenance fitter for 15 years when I was working, we did the grease on drills and taps many a times and have done it when I had to helicoil a striped tread on my BMW oil filter cover and have also done a mate's sump plug this way without any problems.

Ashley
 
The alloy swarf might not be too much of an issue but the tang on the helicoil is. You need to track that down and remove it. Spend some time making sure you tap square to the boss face or your drain plug washer might not sit down properly. In other words, don't rush this job.
 
Timesert worked for me also .... worst part was working on the floor ( no lift ) .... I followed instructions I found on here .... quick and easy , plus I have 4 more timeserts in stock .... hope I never have a use for them ...
Craig
 
Easy for me to joke around about this as it was the last drain plug removal before a full tear down and not the first one during break in. I've used the grease trick before and know it works, but I like the looks of the repair offered by Old Britts mentioned earlier in this thread. At the same time I could have them do their '72 case oil scavenge hole and breather mods. I'll check with Old Britts, but are there any other mods to the cases I should be considering at the same time?
Bill
 
The Old Britts 72 oil scavenge mods leaves the oil pump open to all debris, instead of taking the rear weir away completely you can drill several small holes into it and a hole to join them onto the hole in the other crankcase.
 
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