shadowster
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what would cause a rocker arm to snap in half , happened 2 weeks a go to a mate of mines slitty then it happened again yesterday to another one, any ideas
rocker arms
- Thread starter shadowster
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If hydraulic lifters did one malfunction?or overrevving..I had one break on a flat4 citroen GS years ago & I used to rev the nuts off it
shadowster
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If hydraulic lifters did one malfunction?or overrevving..I had one break on a flat4 citroen GS years ago & I used to rev the nuts off it
he has only had it for a week , dont think he has over revved it. i was thinking the camshaft was bent
jamescronin
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Presume that the tapit spaces are set correct - if its too small and the engine gets hot then snap
First, forget all about a bent CAMSHAFT!
These are so hard they don't bend. EVER.
You might SNAP one, but you won't bend one.
Either ...
It's fatigue failure - just too many operations, but I think that is unlikely, and VERY unlikely to happen twice so close together. Was the second broken rocker from the same cylinder?
Or ... a valve has been obstructed somehow BIG TIME, usually meaning it has hit or been hit by a piston, or an OBJECT has become sucked into a cylinder and gotten trapped between a piston and a valve, stressing the rocker so much it snapped. In Landy engines it is usual for pushrods to give way and bend, but other engines may have other components fail instead. Basically, when it happens "something in the valve train has to give".
Someone with a "practiced eye" would be able to look at the break points and tell you if it was FATIGUE or IMPACT STRESS.
Is he running with the air filter element missing?
CharlesY
shadowster
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just been told this is the 3rd rocker arm ,all diffrent ones . no black smoke or loss off coolant
That is very interesting.
Someone has probably done something silly to the engine.
Like ... no valve clearances?
Failed hydraulic cam followers "pumping up" causing valves to hit pistons?
Head skimmed too much causing that same problem?
Maybe it has just been a dodgy batch of rockers. I would like to see one of them - both bits.
CharlesY
ratty
I'm not special I'm limited edition
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Check the c shaped springs between the rockers are still intact. It's not unknown for them to break-up causing the broken bits to float around under the rocker cover.
That's a very good point.
In Minis and BMC A B and C series engines in general, the rockers were "spaced" apart by coil springs on the rocker shaft. In Competition engines at high revs, it was not unknown for a rocker to shift SIDEWAYS along the rocker shaft, come off the tip of the valve, then smack the Collar down allowing the collets to jump out ... and the valve to drop into the cylinder ... Oh Deary Me ... what a mess.
This problem was solved by taking off the spacer springs, throwing them away, and fitting loose tubular spacers between the valve pairs. Problem solved. Valves could not slide sideyways ever again.
Maybe the Slitty has had that sort of problem? What's the exact engine make and model? We can look up the parts diagrams and see if that might be the cause.
Well done Ratty!
CharlesY
