Hello,
I've got a broken pushrod! One cylinder was not firing, and once I had taken the rocker cover off I could see why - a snapped pushrod...
I've managed to get it out, and I've noticed some odd wear on it close to where it broke.
Is this wear normal or is it a sign of something wrong? Is there anything I can check before I fit the replacement pushrod to be sure that one won't snap too.
Thanks
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The push rod is a later type and not original Morris Minor.
These push rods are very strong and not prone to failure.
There are two lengths of push rod fitted to the 'A' Series.
Short............ for the 803cc/948cc & 1098cc engine.
Long............ for the 1275cc engine.
They are usually interchangeable in full sets without problem in a standard engine and to a modified engine with care.
What engine have you got fitted and what modifications have been carried out to the engine?
The cause of the problem appears to me as either a bent push rod and/or the rod has been rubbing on the edge of the push rod tube in the head.
Check the rest of the rods for trueness by rolling them on a sheet of glass. Any out of true will be obvious to the eye.
Extreme care must be taken when assembling the rods and rockers onto the head as any misalignment can have disastrous consequences.
I'll fit the replacement pushrods when they arrive and turn the engine over by hand for a bit to see If there is anything obviously wrong or rubbing. I don't particularly want to get the head off if I can avoid it!
Just the one pushrod - that was a typo. Having read some horror stories on the internet about broken bits of piston ring getting wedged between the valve and piston I decided to use my newest tool - a USB boroscope!
Luckily there doesn't appear to be anything like that in there, quite cool to be able to see in the cylinders without getting the head off
Use that scope to look down the push rod tube in the head and see what marks/damage there is.
I would suggest that the tappet cover is removed and the cam follower for the broken push rod is extracted and examined for damage before fitting the replacement push rod.
How old was the pushrod that broke? If recent maybe there was just a defect in the metal that somehow got through quality control. I second Phil's advice, I'd also check the rocker for alignment and the valve in case it is bent or somehow getting stuck.
The wear on the side of the pushrod does appear to have been caused after the rupture so I wouldn't worry too much about that.