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Broken Pushrod at 2000 Revs


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The engine is an FRE with unknown mileage - but it won't be very high. Rod is from inlet valve on No3.

I drove 2 miles home with this, I knew I was on 3 cyls but didn't know why, kept going as oil pressure and engine temp were normal. Engine sounded fine.

Got the little bits out with a magnetic tip. Oil and filter change next.

Counting myself lucky.

Bob

Broken Pushrod 1.jpg

Broken Pushrod 2.jpg

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21 minutes ago, Ian Vincent said:

But why did it happen?

rgds Ian

+1

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Cam follower seized in bore or rocker has jumped the pushrod cup and caught on the edge causing excessive depression onto camshaft. Check the cup edge for bruising and try it on the rocker ball for fit.

Mick Richardsu

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is there a corresponding split on the other side of the rocker end of the pushrod. i.e. 180 to vertical split.

That has been forced hard onto a knife like edge perhaps the other broken end of the tube from below or cam bucket.

stuck valve? only thing i can think of that would stop upwards movement.

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............or valve seized in valve guide.

If the guide seized solid with the valve closed then the rod would bend/break.

If the valve was partially open and the guide seized (simply slowing its return) then rod could flop out and the rocker then cause havoc

 

If the cam follower seized (it would have to be in the uppermost part of its travel) then that cause the valve to remain open and the rod would survive.

 

Roger

Edited by RogerH
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Interesting thoughts thanks chaps -

Nothing else was noticed when the replacement rod was fitted in terms of damage etc.

We did 75 miles today to the East Region meeting and she ran like a dream - the only replacement part used for the repair was the new rod.

Here she is at The Manger PH Suffolk meeting today.

Pushrod failure is still / currently a mystery to me.

Bob

The Manger meeting June 2019.jpg

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Fuel ?

Happened to me about ten years ago. Broke a rocker too. Theory is that the fuel companies were experimenting with formulations (or got it  wrong) and it caused valves to bind. There was a lot of anecdotal chatter around at the time but no evidence. As a precaution I reamed the valve guides. It never happened again.

Jerry

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6 hours ago, jerrytr5 said:

Fuel ?

Happened to me about ten years ago. Broke a rocker too. Theory is that the fuel companies were experimenting with formulations (or got it  wrong) and it caused valves to bind. There was a lot of anecdotal chatter around at the time but no evidence. As a precaution I reamed the valve guides. It never happened again.

Jerry

Interesting. BP Ultimate is designed to strip deposits off fine-tolerance modern engines, they promote it as such. Have wondered what the consequences for older motors needing oil or ZDDP-films to protect rubbing surfaces. Peter

 

 

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