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2024-06-11, 21:02:05
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Removing stucck crankcase through bolts

Started by Ian, 02 Nov 2016 at 01:56

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Ian

Folks, need to tap into the knowledge available here. I have a 1914 veteran engine that I am in the process of pulling apart in preparation for restoration (not Douglas !). While the castings are generally in very good condition the crankcase bolts not moveable. I expected they have rusted/corroded in place. Given the age of the castings I am not keen on applying heat.

One option is to get them all very carefully drilled out - may end up taking it to an engineering shop

However I would like to explore other options. I have heard of people soaking the motor in different solutions which remove the corrosion - but not sure what.

Any suggestions ?

cardan


Hi Ian,

Sadly there is no magic. If they are really stuck drilling them out is the only safe approach. It's not exactly easy, but neither is it really hard - the biggest problem is supporting the motor while you drill. My general approach is to use the drill press (I don't have a mill), with the lower end of the job carefully located on axis. If you use a centre to locate the lower end of the stud, there's not much scope to go wrong. I start small and go up 1/64" at a time, but then my time is cheap.

Cheers

Leon

Ian

Thanks Leon, I have a drill press but no real way of supporting the motor accurately. Think I need to buy more tools !!

I guess you have a good idea of which motor I am talking about

oily bloke

Spark erosion is a very good way of removing broken/stuck studs and bolts. Here in the UK I get charged about £20 per hole. Leaves no residue and leaves the thread intact.

Doug

I have removed stuck head studs on a Scott by shorting them out with an arc welder. Works like a electric rivet heater. The stud turns a dull red and then you let it cool down. The expansion and contraction creates a very slight gap that allowed the stud to unwind quite easily. A couple of warnings.

1) Not for the faint of heart!
2) You will need about 250 amps. DC heats more quickly.
3) Make sure the current path flows through the stud/bolt. I my case I grounded the cylinder block and shorted the electrode (a piece of 5/16 inch rod) to the top of the stud. The current followed the path of least resistance and so primary flowed through the stud. The aluminum oxide surrounding it acted as an partial electrical and thermal insulator. You will need to ensure you are grounded to the opposite end of the through the head/tail of the bolt/stud.
4) Do not go beyond a cherry red; you do not want to melt the surrounding aluminum. On the cylinder head, this actually would not have been easy due to the mass. But on you crankcase the bolts might pass through ears that do not have a very thick wall. Approach in stages. Try a dull red, and if not loose, try a little more time with the current applied.
5) Do not try to remove the bolt/stud while it is hot. The steel is at a weak state and is expanded into the aluminum even more tightly than before. Let the expansion and contraction do its job.
6) Don't electrocute yourself!

-Doug

cardan


Hi Doug,

I must have a faint heart!

While we're talking about this Ian, maybe drop the motor in a drum of diesel and let it soak. Something might go in. Have you tried a gentle tap on the bolt with a copper mallet?

Just yesterday I was in the shed trying to sort out a "restored" 1914 Villiers motor for a friend. The "restorer" (not me, and not my friend) had put in new main bronze main bearings, but left 0.075" end float. I drew out one side and shimmed behind the "rim" of the bush, but the other side was stuck fast. I has to stop because I honestly feared the crankcase was in peril. Not to worry, no-one has dies of a slight excess of end float in a veteran two stroke.

Cheers

Leon

Ian

Thanks everyone for input - will probably end up trying all of the suggestions as I work to get them out !

Re the arc welder method - is there danger of the old cases cracking with this ?

Doug

Ian,

In theory the expansion could burst thin sections surrounding the bolt. Doing a bit of calculation, a 5/16 stud heated from 80F to 1500F (cherry red) will grow to 0.315 inches. So it is only 0.003 inch expansion. With the Scott, no hole was closer than 1/4 inch to the edge of the casting.

If you do it too slowly some of the heat will transfer into the aluminum, which will then expand as well (defeating the purpose). If you sneak up on it by gradually increasing the time the current is on, allow the aluminum to fully cool between attempts. Besides the reasons mentioned previously, you are trying to maximize the compression of the aluminum oxide. If the aluminum expands away it will not compress the oxide. In that case you might as well just try heating the area around the bolt/stud with a propane torch and see if you can expand the alloy away from the steel.

The other problem with the Scott was the holes through the cylinder head were roughly drilled, and the studs had a coarse turned finish. the corrosion that formed between had the two keyed together. It was not the threads that were stuck, but the stud where it passed through the hole. I knew I had a problem when it wrung the end off the 5/16 stud rather than turn in the cylinder head.

-Doug

Ian

Thanks Doug - its the same with this one - its not threads that are stuck

eddie

Probably, the easiest/safest method in the home workshop with, maybe, just a bench drill available, would be to make up a drill guide from metal from your scrapbox - then step the bottom face to allow access with a hacksaw. Put the guide over the protruding stud/bolt and clamp/bolt it to the cases - hacksaw off the protruding stud/bolt, then use the bench drill to drill out the remainder. Start drilling at full diameter to establish a centre in the stud/bolt, then change to a smaller drill to remove the majority of the stud/bolt. At this point, the hole may have wandered a little off centre, but the chances are that the drilling will have released some of the stresses that are retaining the bolt/stud, and it will then be easier to 'persuade' it to move in the 'conventional manner'!!!

Regards,
              Eddie.

Ian


Alan Cun

#11
Hello All,
Just had an email from another M/C enthusiast about maybe a replacement for WD 40 etc. The video shows a chap removing stuck wheel nuts by simply heating with a lighter and melting on candle wax. I will attempt the website-
http://www.chonday.com/Videos/rusnutcankj4
that is how I read it. Any thing is worth a try.

regards Alan

[hyperlink corrected.  03Nov16, Doug, Site Moderator]

Edin

Hello Alan
Please help me with the webside link in your post today,- it is not possible for me to contakt the webside: http://wwwchonday.com/Videosrustnutcankij4.
Is  the adress correct ?
Kind regards Edin DK

Alan Cun

Ah left a dot after www. but have forwarded the original EMAL to Doug he can make it work

Ian

Hi again - I have got most of the bolts out of the crankcase - just a few very stubborn ones available. I think I will get them drilled out by someone with good precision drill press/mill.

Any recommendations for workshops who could do this in Sydney and surrounds (preferably south !) who are vintage motorcycle sympathetic ?