pdm
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| posted on 31/8/09 at 04:06 PM |
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Cylinder sleeves
Afternoon All
Just trying to gauge whether it's a good idea to attempt to rebuild an engine and so have been reading up about engine rebuilds today,
especially the various measurements to check if a cylinder bore is out of round or worn.
I'd been assuming up to this point that when you rebuild an engine, if you bore it it would need oversized pistons and hence more cost.
My question (and apologies if this is basic) is can't you just change the cylinder sleeves instead if you find the bore is sufficiently worn to
require work to avoid buying a new set of pistons (assuming the pistons are ok ? Or if the bore is worn will the pistons be shot anyway ? If you
had to get new pistons are new rods automatic ?
thanks
Paul
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big_wasa
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| posted on 31/8/09 at 04:13 PM |
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Unless you have a rare and or very expensive engine its just not worth the work on a modern engine to try and rebuild it.
For an example the bits to rebuild a zetec are well over the price of a new crate motor.
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pdm
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| posted on 31/8/09 at 06:04 PM |
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Thanks for the response - reason I ask is I am hoping to build a GKD legend.
Donor is a beemer 3 series E36 - post 94' M52 6 pot engines had nikasil sleeves which apparently wear if used with high sulphur petrol.
At the moment I'm trying to weigh up whether I should steer well clear of this engine range.
Whatever I get, even a different kit, I'd like to "rebuild" the engine for the experience - again at the moment given little
experience I'm trying to weigh up whether this is going to be costly though just to indulge a hobby.
I'm thinking I could do a short block and then check the cylinder head for warpage or worn guides etc but farm that work out if it became
necessary.
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big_wasa
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| posted on 31/8/09 at 06:19 PM |
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Ive been looking at them my self, I would like the 1.9 four pot like a 318ti.
Its a nice looking car on them rims. Price looks in keeping with others and a bit differant. 
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dmac
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| posted on 31/8/09 at 06:29 PM |
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nikasil is an electroplated coating and I don't think you can rebore a block that has had this coating as there usually isn't enough metal
left.
Replacing the sleeves in a modern engine is unlikely to be a DIY option, I suspect you would end up with the new sleeves stuck half way in.
Duncan
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pdm
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| posted on 31/8/09 at 06:44 PM |
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Ok thanks for the help so far - so replacing a sleeve is a machinist/shop job.
If I got sleeves replaced, does that remove all the worries about boring, honing and oversized pistons etc - i.e. assuming, piston and rings were in
reasonable condition could I just rebuild the short block with them ? Or if bores are worn does that mean piston and rings are also shot ?
big_wasa - GKD advised any 3-series except the M3 and Compact so not sure Ti would be suitable. BUT the 318iS with the M42 engine according to the
internet beemer forums has forged pistons etc and is a very strong bottom end. The M42 is the 1796cc engine - later M44 1896's are a more
normal spec. (don't quote me on any of that though !!)
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big_wasa
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| posted on 31/8/09 at 07:24 PM |
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cheers for that,
you would be much better buying a low millage donor and running it for a bit to make sure its all good.
Detail and clean the engine but it wont be worth the bother in going any more than that.
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MikeRJ
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| posted on 31/8/09 at 08:25 PM |
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quote:
Originally posted by pdm
If I got sleeves replaced, does that remove all the worries about boring, honing and oversized pistons etc - i.e. assuming, piston and rings were in
reasonable condition could I just rebuild the short block with them ? Or if bores are worn does that mean piston and rings are also shot ?
New rings will almost certainly be required if the bores are worn. There is a good chance that the pistons are scuffed if the nikasil coating has
failed however.
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dmac
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| posted on 31/8/09 at 08:59 PM |
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If you have the sleeves replaced you should also replace the rings but you may be able to use the original pistons if they are not worn or damaged as
the bore will be the same as the original.
Duncan
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