5 replies to this topic

[maryquant]

After four years of waiting I have started to take apart my 998 a+ for a bit of a spruce up but had a couple of what are probably very basic questions.

 

First one is the amount of build up of crud on top of the pistons - is this normal? I've not cleaned anything off but it seems a lot worse than other pictures I see...

 

 

Also just to confirm, this head looks to me like its had no modification or reworking done - does that sound right? 

 

 

 

Also, you may be able to tell from the first picture but the cylinder holes in the gasket were not round, but instead were egg shaped? Am I right in thinking this is for pocketed cylinders and if so was it the wrong gasket?

 

What is the best way to clean the head? When i removed the thermostat there was a crystaly type goo which Im guessing was the coolant, but i imagine that it is everywhere where coolant ran.

 

 

All of the above is just my understanding from what I've been reading - but any clarification is very much appreciated.

 

[HarrysMini]

If you're stripping it right down, I'd get the head acid dipped which will clean out the oil and water ways. Same goes for the block.

 

The pistons can be cleaned with emory cloth, as can the block and head mating faces.

[Mini Mad Drakeley]

head looks to be completely standard and the standard gasket is kinda egg shaped and the crud is just carbon build up. check the top of the bores for any noticeable lip and if one is present after removing carbon then the block may need bored out further. if it is ok then soak the pistons in water as it dissolves the crabon and will make cleaning much easier and i would recommend a scotch pad to assist in cleaning

[carbon]

+1 for mini mad's comment about checking the bores for wear lip.

 

Maryquant - How far are you planning to strip down this unit?

 

If you are not planning to take the pistons out I would strongly advise against using emery cloth on either pistons or bores, or the block face.

 

Reason for this is bits of emery will very likely drop down between piston and bore and you will soon find you have one seriously smoky engine... Even if you are taking the pistons out I would avoid using emery on any machined aluminium surface which is mission critical as small particles of emergy can get embedded in the soft metal and cause havoc later.

 

For cleaning the tops of the pistons in situ my favourite is the stainless steel pan scourers - the ones in one piece made up of coiled stainless steel. But before using put grease down the bore around edge of piston with the piston about 10mm down the bore. For softening the carbon deposits I would recommend something oil based such as WD40, engine oil, white spirit. Then once clean remove grease by taking piston to top of bore.

[KernowCooper]

If the engines done a few miles and your not reboring and new pistons I'd not be cleaning all the carbon off the outer edge, otherwise smoking could be the end result.

[maryquant]

Id like to strip it completely if for no other reasons than I might learn something along the way, and it wasn't best maintained in the first place. Might be a good opportunity to do some subtle modifications or improvements to it too. I'm in no hurry as the shell is still miles off so I can take my time with it. If I recall its done around 90k 

 

The cylinder head may need to go in to a machine shop anyway as one of the thermostat studs snapped so will need to be extracted.

 

If stripping it down completely is the best approach to just fully dismantle and then examine the individual components and replace as needed whilst building back up - or is it a case of only dismantle if 100% necessary?