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MG MGF Technical - Gudgeon pin removal

What is the proper method to extract the gudgeon pins from the pistons in a K engine? They are press fit in the connecting rods and floating in the pistons. No circlips locate the 'pins, so the do apparently have to go in a press to come out?
My plan is to make a cradle from a piece of wood with a hole in it for the gudgeon pin, heat the piston/rod in a stove and press it out with a hydraulic press.
Any better ideas?
Jon

Jon

I'm not a mechanic but I've just been through the CD Workshop Manual and there is no mention of gudgeon pin removal. This is a first for me in more than 35 years motoring on 2 and 4 wheels.

The exploded view of the block shows the "piston/conrod assembly" as a one piece with a single part number.

I did find the following 2 NOTE & CAUTION in the Engine Overhaul section.


NOTE: Pistons and connecting rods are only supplied as an assembly.

CAUTION: Removal of pistons will necessitate removal and re-sealing of cylinder liners.

Hope I'm wrong.
JohnP

Presumably the rod and piston make a balanced unit and to take it apart could upset this.

Ted Newman

The rods may be shrunk onto the gudgedon pins. Well, as no pistons are available separately I think there is no point in splitting the piston/rod assemblies.
Cant's see why the liners should be removed from my particular (which is my spare) engine, though. They sit quite firmly in the block and I thind they will have to be knocked out.
Jon

When aftermarket compressor is added to the engine shorter rodīs are installed together with the old pistons.... So surely there is a way to do it properly. / Carl.
Carl Blom

The reason why I want to replace the pistons is that they apparently are from a batch that that went into some engines that eventually were replaced on warranty. My engine is one that was saved from the scrapyard.
It has been burning oil (the pistons crowns and skirts are black) and the scraper rings are stuck in the grooves. The skirts have marks looking like they have seized, though the bores are perfect.
If the piston/cylinder clearance is within spec (I have not measured them yet) the pistons may be re-useable. The problem may be that the scraper ring groove clearance is too tight. When I get the things clean and checked hopefully a set of new rings may be all I need.
Jon

Hi Jon,
in the engine manual it says " the gudgeon pin is a tight fit with the small end (of the rod)".
So if the small end was heated by a gas torch at moderate temperature ,maybee the pin can be gently pressed out before the pin gets up to equal temp as the rod ?? / Carl. (With blood on my hands after half-way thru a VVC cambelt change ;O)
Carl Blom

It is not easy top remove the pistons from the rods, heat is no help, the correct way is to support the pistons and press the guidgeon pins out, the problem is supporting the piston which has no flat surfaces. I have a mold of the piston which I use to support the side while the pin is pressed out, it works flawlessly. The new pistons can be put on by heating the rod eye and freezing the pin, the pin will then drop through the rod eye and as the two temperatures stabilise it will become an interference fit again.

I have a number of new later type pistonsd with pins here FOC to anyone who wants them. You could send me your rods and I can remove the pistons for you and fit the new ones.

Dave
Dave Andrews

Dave, thank your for your generous offer! Yes, I'd be very grateful for your assistance to replacing my pistons. Of course I will pay you for the parts and the labour, though. I'll send you an e-mail for address details.

My engine's serial number is 14K4FK76 258174. Any idea which year and car model it comes from?
Jon

>14K4FK76
Me with no sense (this time)

quick google search found
http://www.mg-rover.ru/Templates/FAQ.asp?Page=47&RubrID=6
Looks like a Rover type with *sample VIN*
SARRFMNHMXD390555

wherein ...RFMNHM... is about the car type.
Is RF ? R200 ?
Dieter K.

Jon,
the engine you have is a 1.4 litres.
Pete C

Indeed it is a 1400. Bore is 75mm, so the block is worthless. Fortuneately i got the engine for free, so I do not suffer a big loss. At least I still have a good spare cylinder head. What fooled me was the head gasket - it is the same as in my 1.8.
Jon

This thread was discussed between 05/02/2005 and 10/02/2005

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