Is pushing out gudgeon pins that are interference fit in the little end a diy job, say with a drill press? Any hints, tips or snag advice will be welcome.
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I've done it in a vice using a piece of bar just a little smaller than the pin and a lump hammer. the main thing is to make sure the new one goes in square and tap gently. You could also try heating the piston in the oven and cooling the pin in the freezer to make it easier - personally I didn't bother.
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Heat piston by placing in boiling water for 1 min or so, gudgeon pin should move fairly easily with firm finger pressure.
I wouldn't advise, and it should not be necessary, to use hammers, presses etc
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Many thanks Cyd and Hairyharry for your responses but apparently in this case the pins are an interference fit in the little end eye and therefore presumably a sliding fit in the actual piston. The book suggests removal is a "dealer" job which immediately makes me think that massive presses are required. My idea was to support the piston on a tube and try to force the pin out with a spigot in the drill press or perhaps draw it through with a long bolt. It looks as if a vice would exert more pressure than the drill but I don't think mine opens wide enough. I guess it will be a pretty tight fit.
Any comments?
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In that case leave the job to the experts. Your local engine specialist will probably be cheaper than ford dealer. Should not be that expensive.
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Where did I get ford from? Cracking up.
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Thanks Hh, Proton actually. One guy I approached offered to sell me a better car for less than the cost of changing pistons. So I shall struggle on for a bit.
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Obviously the piston is the weak component here and must be treated with great care. Most important to fully and evenly support (so far as possible) the wall and boss of the piston and, as Cyd said, make sure the pin is perfectly in-line when refitting. I would be far more comfortable using a proper press and a suitable support than using a vice, drill-press or hammer -- perhaps you could ask around the local machine-shops and small garages and get the pins fitted by them for little cost?
I can't recall fitting a pin that was an interference in the small end but I do recall repairing a very-recently overhauled HA Viva engine where the specialist engine rebuilders had broken *two* pistons when refitting pins that were an interference fit in the piston!
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D.Ouch! Am considering my options, if anything of value or interest comes of it will post it here.
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Have managed to get away without having to do this (so far). Have since discovered that the drawbolt method is used and there are descriptions in, for example, older MG manuals and the tool used looks a simple turning job for a lathe owner. Thanks for all your advice.
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Have since discovered that the drawbolt method is used>>
Hanging my head in shame I have to admit I hadn't thought of that, and it has to be the best way for you. Good luck!
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Dizzy,
Nothing to do with gudgeon pins, but I can remember the first HA viva engine I rebuilt (1159cc). New pistons, Crankshaft, oil pump etc. Everything assembled on the bench, engine re - installed. Then I found that the distributor wouldn't fit properly. Impossible to time the ignition. Then I discovered that the oil pump formed part of the drive to the distributor, and had to be timed. Engine out again !
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Like Dizzy I have never come across an engine where the gudgeon pin was interference in the little end - only ever interference in the piston. What engine are we talking about here?
To give more detail: when I rebuilt my SD1 V8 motor to "fast road" c200hp, I made a wooden cradle to hold the piston (in a vee essentially) with a hole for the pin to pass through. it was the cradle that was held in the vice and I then simply drifted the pins out and back in again. I only took them apart to get everything thoroughly cleaned, but the disassembly and subsequent reassembly took about 2 to 2 1/2 hours in total and nothing was damaged (indeed the engine did 40k hard driven miles in my hands).
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Cyd. The engine is a Mitsubishi, 1.5 12v. and they are most definitely an interference fit in the little end eye. Some engines used to have a split little end with a bolt to clamp the pin in, not to mention the fully floating ones with circlips or brass (bronze?) endcaps. I had not come across this method of fitting before hence my original question. I was an enthusiast once but this is the first engine I have stripped for what must be near forty years and now as a some doddering OAP and all that entails I am very pleased to have an engine that I recognise as such apart from that ridiculous piece of rubber that drives the cam shaft. I must say that diving under the car at my age certainly frees things up. I am becoming so adept at taking the pistons out I am thinking of giving public demonstrations, I am not saying why I had to take them out more that once.
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