26 replies to this topic

[rofert]

Stripping down my an engine tonight its a 998 with a 20thou over bore and S type rods, casting number has been ground off and whoever lightened and balanced them has added there own number. Tried to remove the pistons normal way up through the bore but the width of the journal is wider than the bore, so thought pull them out the bottom but this failed as well as the piston skirts don't clear the sides of the main bearings.

Should have got a pic really will do tomorrow, if anyone follows what i've described then how do you get them out without some how removing the gudgeon pins.

[Jordie]

The hole lot should come out of the top. Ive only done 1275 engines, but i would assume a 998 is the same method.

By removing it down the botton, you will have most likely damaged the rings and pistons.

[oxon mini services]

they should come out the top, i dont understand how they are wider than the bore though

[rofert]

First time I've done a small bore like this, but as I said the con rod journal is wider than the bore so it can't go out the top as usual, but won't come out the bottom either.

Really confused.

[lrostoke]

Just done a 998 and the whole lot comes out the top !!

They must do otherwise how would you refit them, it would be pretty impossible to feed pistons back in through the bottom, especially with a ring compressor fitted

Edited by lrostoke, 23 September 2009 - 09:18 PM.

[GraemeC]

It sounds like you are tring to do it with the crank still in place - make your life easier and remove it (plus check its bearings etc whilst it is out).

But as said - they should come out of the top as they need to go in from the top.

[benpopham]

Are the big end caps off?

[lrostoke]

Are the big end caps off?

eeerrrmmm they must be you can't move the piston assy up or down unless they are off. Its what attaches them to the crank
Not unless he undid them turned the crank and bolted them back on ??

Edited by lrostoke, 23 September 2009 - 09:29 PM.

[benpopham]

well... he might of lol??

[mini_mad69]

You should be able too slide them out. I dismantled a 998 yesterday.

It can be done, is easier if you remove the crank aswell, although I managed too do it without.IF you do get the problem of the bigend touching the bottom of the cylinders turn the crank and you should be able too pop them out.

If you remove the crank you can take them out from the top or the bottom I think.


Ben

[Paul Wiginton]

What do you mean 998 with S rods? S rods are 1275.

998 rods have offset caps so they can go through the small bore. Will they go if you take the bolts out?

paul

[mini.rich]

Stripping down my an engine tonight its a 998 with a 20thou over bore and S type rods, casting number has been ground off and whoever lightened and balanced them has added there own number. Tried to remove the pistons normal way up through the bore but the width of the journal is wider than the bore, so thought pull them out the bottom but this failed as well as the piston skirts don't clear the sides of the main bearings.

Should have got a pic really will do tomorrow, if anyone follows what i've described then how do you get them out without some how removing the gudgeon pins.

Not had much experiance with 's' rods in 998 blocks, but from what i remember the 998 gudgeon pins are held in with circlips and the pins are free floating, i would assume its the same with +20 pistons, so with that in mind, can you remove the piston enough through the top of the block so you can remove the circlip and gudgeon pin. Then draw the rod back out the bottom?
Thats about the only way i can think of without actually seeing it

[Dan]

That's what I was thinking you'd have to do. Odd combination, S rods in a 998.

[rofert]

Thanks for ideas so far, to let you know the crank is out and the rods are 1275 type ie not offset journal. Having a feel the gudgeon pin does seem to be circliped in.

Will have another play tonight, will try and get a pic as they say more than many thousands of my words.

If it all comes apart it the bits will be at Castle Combe for sale, along with some S/C drops and a few other bits.

Rofert

[rofert]

Pictures at last. I have got number 4 out but no joy with the others.

Journal bigger than the bore so can't come out the top.



Drawing down the rods and the piston skirt won't go past the casting of the main journals.



Have tried to get at the circlips to remove the gudgeons and no access, but discovered that the damage to the bore (why the engine came out) was caused by the bit of circlip I found in the sump which was off No2 piston gudgeon.

Any other ideas except for the big hammer technique....