cracked lug - weld or epoxy?

beauchemin

beauchemin

Senior member
Location
Victoria, British Columbia
I have a minor crack on one of the lugs on the crankcase.  It is one of the primary cover lugs, just below the oil pump.  Should I bother getting it welded, or maybe just fill it with some kind of epoxy?  Or, just leave it alone???

I have no idea how it happened.  I believe this is the first time the motor has been out of the frame.  I never dropped or bumped it during the removal process.

normal_cracked_lug.jpg
 
At a guess I'd say someone used too long a bolt and it bottomed out and they kept tightening, on the other hand it might be just a shrinkage crack from the original casting process.  What's the motor's history?  Was it running before and was it leaking?    If the motor's new to you and there's any evidence of a crack on the inside I'd be inclined to weld it, otherwise leave well enough alone.  I would not do epoxy etc.
 
I had one bust like that on my Kawasaki. I was screwing the cam cover back on (about 36 M6 bolts) after checking the calve clearances. I felt one of the bolts tighten up a little bit, but not enough to worry about. Then it went "ping" and fired a piece of metal across the workshop. A finger-nail sized piece had popped out of the cylinder head casting at the back end of the threaded bolt hole. I thought I must have picked up the wrong length bolt, as Steve suggested, but when I took it out and checked, it was the correct bolt for that hole.

The only explanation I can come up with is that some oil had dribbled into the hole while I had the cam cover off, and caused a partial hydraulic lock when I put the bolt back in the hole. The pressure inside the hole as I tightened the bolt was enough to blow a piece out of the casing.

The piece that broke was actually a couple of mm beyond the end of the bolt in the fully screwed-in position, so it wasn't a structural problem (bolt still had full length of thread to screw into). I could have just left it as it was without further problem, but it was in a visible spot so I epoxied the piece back in as a cosmetic repair.

Cam
 
Check to see if there is any silicon locktite ect in the bottom of the hole.You never know whos been slaverling what where
 
Dellortoman said:
I had one bust like that on my Kawasaki. I was screwing the cam cover back on (about 36 M6 bolts) after checking the calve clearances.
Click to expand...

Does that mean it was actually a Cowasaki???  :D :D :D
 
Hydraulic damage, always clean the threads out with a tap on an unknown motor, all manner of old gasket goo, over enthusiastically applied coppaslip etc. can lurk in the bottom of blind holes.

Best just to clean all the threads out, probably would not attempt any repair as the lug is still sound and will hold the case screw fine.

  Keith
 
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