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Removing pistons


PeterK

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I've started stipping down my 1979 3.0SC engine.

Heads and cams came off easily enough, but am really struggling to get the pistons off.  As I assume that I have Alusil cylinders (no KS marking, but light grey inside the bore and my fridge magnet won't stick), I'm removing the pistons whilst still inside the cylinders, rather than cylinders off then pistons off.  Rotated the crank to access No.6, circlip removed and Uncle Wayne's book says pull the gudgeon/wrist pin out, maybe use a bent screwdriver to pull it out as they are not tight (or words to that effect).  Well I've pulled and pulled but it didn't want to come much further than the edge of the circlip groove.  I've looked for any marks / burrs but can't see any.

Swapped to No.4 - circlip our, pulled at the wrist pin again with little success.  Used a length of threaded rod, passed it through the wrist pin and added a not and washer to the end.  Using a set of pliers to grip, I could then tap the pliers and finally pull out the wrist pin.  Back to No.6, and using the same technique, the wrist pin is still only half way to where it needs to be to free the pistons.

 

So, what am I doing wrong, what are the tips and tricks here, please?  I'm scared to keep tapping (pulling on) the wrist pin and putting sideways loads on the connecting rod.

Peter

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Peter, from memory I think I used a long 3/8" drive extension to tap them out, rotating the engine to gain access. While they are still in the cylinders, they can'y move too far sideways but you will be replacing the big end bearings (at least) anyway right?

Chris.

 

 

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Thanks Chris

I assume from your comment that they will tap in enough to release, before they hit the adjacent piston.  Yes ?

Peter

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Yes, indeed. reassembly takes some thought to gain access to put retaining clips back in but disassembly is quite easy. I think gunge gathers outside of the gudgeon pin clip in the piston and just a 1000th a mm less clearance makes them stick not slide out easily. Be SUPER SUPER careful not to ping a clip inside the engine.... Ask me how I know! Good luck!

 

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Well, I got a bit braver and gave No. 6 a stern talking to.  Using my 8mm stud bar with a washer and nut on the end (slightly stressful putting them on and off the stud with the risk of dropping them into the black hole that is the case), I bent a 90' end so that I could get a firmer grip and with a light tappy tappy with my medium sized hitting stick of choice, it is now cowering in a plastic bag 😎

Thx all

Peter

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