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Discussion Starter #1
Hi All, whilst following a number of pages and advice I have been rebuilding a cx. Many of you have been a big help already so far. I was up to the water pump propeller and after following a shep method on the mech seal a few weeks back I finally found time to reassemble. Only problem, I followed the JC's motofaction page which is always really helpful but when trying to tightening the acorn nut to 6-9lb/ft as specified on the site, I've got an acorn that doesn't want to come off as I think I've stripped the inside of the nut. I actually hope I did otherwise I've [email protected] my cam (which I've just replaced)!!! Can someone please tell me that the material the acorn nut is made from is weaker than the cam itself. Any suggestions on removing the acorn without doing further damage. I have a spare nut so no need to salvage. Please help
 

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:/

Did you have the copper washer beneath the acorn nut?

You mean it's spinning freely when turned anticlockwise and not backing off?

6-9ft/lb is the correct torque for that nut as per the FSM :( It's a fairly low amount - I use a little 1/4" torque wrench for that as the 3/8" I have doesn't go that low.
 

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Discussion Starter #3
Yeah sure did JC. I know now after doing this I shouldn't have used my big 3/4 torque but had no idea prior.

Any ideas? JB weld?
 

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Have you got the nut off yet?

If not, try turning it out with a spanner while pulling slightly on it.

If it's the cam that is damaged I can't help you, but I do have stocks of the nut both new and used.

Which was it, - 6 or 9?

I do them up to 90 - 95 inch pound {7.7 ft/lb} and use a medium strength thread locker. With a 1/4" drive torque wrench.

I wouldn't use 1/2, or even 3/8" on these.

You do know that a torque wrench is most accurate in the centre of its range and not very accurate at the ends
 

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I have added a note to the impeller install page about torque wrench sizing to try and reduce the chance that this sort of thing happens to anybody else :/

I'd try some rearward pulling - needle nose locking pliers might help if you can't get purchase with a spanner - to try and apply some gentle rearward force while attempting to unscrew it to see if that results in the acorn nut coming off... someone else may have a better idea, though.
 

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Discussion Starter #7
Thanks guys, will try and remove over the weekend. I'm thinking some gentle heat and a set of multi grips might be useful. Really hoping that the cam is ok and only the nut is knackered.
 

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You can grind down the acorn nut until you get to the hole in it and see the end of the camshaft, then you will have a better idea of what is there and access for any lube you want to squirt on it.
 

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I am not exactly sure of the metal characteristics of the two items, but I tend to think the acorn nut would be the softer of the two. And since you are binning the nut anyway, if the cam end threads are bruised, they might be able to be turned back to a state they will still be able to get the grip.
 

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At this point, instead of throwing out the camshaft, you might as well weld a nut on, nut an acorn one, because that cannot be rethreaded, although nothing says you can't try.
 

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Man oh man Tom, your luck is running like mine of late...

I will be interested to read of Murray's fix.

If you pull your electronics that would be damaged by welding on the bike I think I would try to clean it up with a file and build up a weld on the threads to cut new threads in or put a threaded sleeve over it staked and epoxied into place. After cleaning it thoroughly and cleaning up the damaged part could you wrap it with a good steel wire with a thick epoxy in the layers to build up something you could then cut threads in? A spitball idea. I was thinking a wire because building up a weld on the part and then cutting or filing it back round to make it ready to cut threads again strike me as very difficult. I guess you could not try to do the entire part but do it in stripes at 4 points and a template on the shaft beyond it could help you bring it back to size using a files...then cut threads in that.

Ideally out of the bike is the way to approach any repair short of a glue style repair, but I am betting pulling the cam on the CX/GL motors is worse than doing it on a Pushrod motor in a car.
I only have 4 cylinder Volvo B18/B20 pushrod motor experience...so I am clueless on domestic V8/V6 pushrod design and I have only messed with one Honda pushrod motorcycle motor, '65 CA95.

Good luck! I am sure in JC and Murray's guidance and others here you can get this fixed without changing out the cam.

David
 

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Discussion Starter #15
Thanks David. Actually problem completely fixed in the matter of an hour. As i expected, the camshaft, including the threaded end is made from a much denser material than the acorn nut and luily it was the acorn nut that was completely stripped. Once removed, i saw that the lighter colour metal on the cam thread was the thread of the acorn nut which after picking as much of it off without doing any more damage to the cam. Once cleaned up a little, i was able to run a tap and tie of the orignal thread size back over it gentle and reveal a delicate cam thread. I then used a shim washer instead of the copper washer which was thinner and reassembled.

Fingers crossed that will fiz the problem!
 

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Isn't one of the functions of the copper washer to crush and thus seal to prevent coolant from seeping past the acorn nut? What is the shim washer made from?
 

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Discussion Starter #17
It's made from steel I think but really thin so will provide the same functionality I think
 

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YES. The copper washer 6 mm is functionally the best to prevent coolant leakage between the impeller end and the base of the cap nut. A steel washer in that spot might allow leakage. The steel washer 10 mm on the inside of the impeller and the polo mint washer around the shaft should preferably also be changed for a new part when servicing the water pump. ( there is a danger that this washer can be seen as part of the cam shaft and should not be "doubled up" on refitting a new one !!! ) Both these washers ( outside copper and inside steel ) should be the right size and consistencies to ensure proper fitment of the impeller onto the camshaft's end to ensure no leakage and also trouble free spinning of the impeller behind the water pump cover.
 
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Plus: The cap nut ( acorn ) should be torqued to a max of 12 Nm .... And: to use a good quality "lock tite" solution on the treads on the end of the cam shaft when fixing a brand new cap nut, is a good idea. :)
 
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