2.5v6 liners - Alfa Romeo Forum
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Old 25-08-12 Thread Starter
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Cry Like A Baby 2.5v6 liners

Hi All,

I'm in the middle of an in-car head gasket replacement on my v6. Both heads are off and I'm cleaning them up ready to refit...Until yesterday I was starting to get a sense of good progress, having successfully over-come the major hurdles (crank nut and rear manifold stud nuts)...

But there always seems to be 'the next thing'...and it is this....

Whilst doing the final clean up to the piston crowns I found that one of the cylinder liners is now turning in the block. This does not seem good, but maybe (clutching at straws...) this is 'normal' ? I am aware that disturbing the liners is a bad thing and have been careful. The crank remains locked off and has not turned. None of the liners has lifted at all...

...The sump was already empty but drain nut fitted...I opened it and oil/water came out...luckily I realised that in getting the heads off some water would have gone down the oil passageways so I have flushed clean oil down all the oilways and out the drain plug and now there seems to be no water in there.

Questions:

1) If I leave the block half full of water for a few days and no more water appears in the sump can I assume that all is okay and I can go ahead with refitting the heads ?

2) If there is water in the sump, what chance of lifting the liner in situ, cleaning up the seat, remove the old O ring and slide a new O ring down the outside of the liner ? It is the front centre cylinder so luckily the piston is at TDC and the liner can likely be lifted a long way without the rings springing out ?

Grateful for any helpful comments...particularly from someone who has been here before (sure there must be a few !)

Many Thanks,

Mike
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Old 25-08-12
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Option 1) is not a safe bet.

If you really don't want to do a full engine strip down to change the liner seals properly, option 2) makes more sense. We normally lock down the liners by fitting some home-made bars over the head studs with some spacer tubes and then nuts torqued down, so that the liners physically cannot lift. But we can't guarantee to someone that after doing a HG change only, liner seals will not leak. Its one of them gambles - mostly they won't leak but you always get some that do.

I would say a new liner seal on the middle cylinder only is not going to guarantee success - just because this one is turning it doesn't mean its the only one that may have leaked. However I think do stand a good chance of fixing it. Its a waste of a pair of headgaskets and a lot of time if it all needs to come apart again though.

If you do go down the path of a new liner seal on the middle front cylinder only then also put some silicone sump sealer around just to give it a better chance of sealing - as you aren't taking the liner out it doesn't give you good access to clean up the sealing surfaces very well, so in this case a bit of silicone may help.

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Old 25-08-12 Thread Starter
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Thanks!...kind of what I feared I'd hear. I haven't looked into dropping the sump off as yet. Are there any major snags? the one thing concerning me was the air con pipes running underneath it...but as my aircon does not work, maybe there is no gas in there anyway...

So as a general plan of attack i'd leave the crank locked off, remove clean and refit each liner/piston/rod one at a time? Are there any problems accessing all the bearing caps or will I need to turn the crank?

Are the O rings easy to get/off the shelf?

Thanks again for your help so far, its much appreciated...
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You'd need to turn the crank to get at all the bearing caps, I'm almost certain of it. You can undo the bearing caps and lift the liner, piston & half the rod out through the top without disturbing the crank. Re-fitting them means turning the crank before the heads are on to replace the bearing caps, so you would need to insert certain liners, lock those particular liners down, replace bearing caps, turn crank, fit remaining liners, lock down, replace caps etc etc.. Can't remember if you'd need to turn the crank just once or twice - this is not the way we do it though, we would take the full engine out and do a bare block rebuild if it needed liner seals. It makes sense to do big end bearings, main bearings, thrust washers, grind/polish crank, dynamic balance of the bottom end, re-face flywheel, re-hone liners and change piston rings, change front & rear crank oil seals and all the other oil seals, rebuild oil pump, replace clutch etc. If you don't have a ramp though this adds a lot of difficulty but I can't see that you are replacing the cylinder head gaskets and liner seals just to sell the car on, you would be mad to do that. So assuming you're planning on keeping the car long term, it might make sense to give it a full rebuild rather than half a rebuild.

I can't remember what O-rings we use, we don't keep these parts in for the 2.5 V6, only the 3.0 and 3.2.
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Old 25-08-12 Thread Starter
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Yes, this car is a long-term keeper. I'm keen to do the best job I can, but within some limits as I only have a domestic garage , tools etc. Gonna do other stuff this w/e and contemplate the next step over a few beers, Many Thanks again for your input,

Cheers, Mike
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