Omega Owners Forum
Chat Area => General Car Chat => Topic started by: JamesV6CDX on 10 March 2017, 17:59:04
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Just doing final clean before refitting head hopefully tomorrow. Span the engine by hand to wipe the bores clean.
Found this.
Gutted doesn't come close to covering it.
(http://www.uk-chat.co.uk/BMW/boredamage.jpg)
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Nightmare.
Afraid I can't offer advice on how terminal that really is. Perhaps it'll just lose a tiny bit of oil and compression will be a bit down on that cylinder??
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I'm more interested in how it's happened? I don't recall seeing it before but then I didn't inspect the bores, and this one was close to the top before I gently spun the engine by using a hand on the pulley
Is it something that I could have done having turned one rotation by hand? Or must it have been like it before!
You can't feel it with a fingernail or finger. The car never used any oil before :-\
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Would a glaze buster help to tone the marks down :-\
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Has something caught in the ring? Poss ring damage? :-[
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Could be...has it ever over heated in a bad way
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Could be...has it ever over heated in a bad way
Never in my last 20k of ownership
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Looks like something has been trapped between piston on top ring whilst running, unless it's majorly scored (depth), I'd just use some 2k grit wet and dry to smooth it off.
But I'd say take the piston out to inspect and clean before doin any of that, if the foreign body is still there it'll get way worse.
Hope you've caught it before to much damage is done.
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Taking the piston out isn't really an option :-[
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I'm more interested in how it's happened? I don't recall seeing it before but then I didn't inspect the bores, and this one was close to the top before I gently spun the engine by using a hand on the pulley
Is it something that I could have done having turned one rotation by hand? Or must it have been like it before!
You can't feel it with a fingernail or finger. The car never used any oil before :-\
Probably nothing then. Maybe a bit of carbon fell into the gap between piston and bore when the head came off and wiped the oil off when you span the engine by hand? :-\
It is more or less in line with the gudgeon pin so isn't on a face subject to sideways forces (and hence wear). If I squint I think I can still see the factory honing on the bore surface.
Unless you drop the sump so you can't undo the big end bolts to lift the piston out for a look-see so get the head back on and forget about it........
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I'm more interested in how it's happened? I don't recall seeing it before but then I didn't inspect the bores, and this one was close to the top before I gently spun the engine by using a hand on the pulley
Is it something that I could have done having turned one rotation by hand? Or must it have been like it before!
You can't feel it with a fingernail or finger. The car never used any oil before :-\
No - That happened with the engine running.
Maybe it was an artifact released by the death of the turbo?
I still think it was something soft (not a piston ring) and not something to lose too much sleep over
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I'm more interested in how it's happened? I don't recall seeing it before but then I didn't inspect the bores, and this one was close to the top before I gently spun the engine by using a hand on the pulley
Is it something that I could have done having turned one rotation by hand? Or must it have been like it before!
You can't feel it with a fingernail or finger. The car never used any oil before :-\
No - That happened with the engine running.
Maybe it was an artifact released by the death of the turbo?
I still think it was something soft (not a piston ring) and not something to lose too much sleep over
Sure? That makes me feel a little better as it ran sweet before :y
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Missing circlip on the end of the pin? :-\
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Missing circlip on the end of the pin? :-\
Eg the pin holding the piston to the rod? How would that have happened? :-\
If we're certain this scoring happened when the car was running, before it was dismantled, that makes me feel a bit better. I was worrying it's something I did during the repair process :'(
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Taking the piston out isn't really an option :-[
I don't know how big of a deal it is to remove on your car but usually just drop the sump and undo the 2 big end Conrod bolts and out it comes?
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Taking the piston out isn't really an option :-[
I don't know how big of a deal it is to remove on your car but usually just drop the sump and undo the 2 big end Conrod bolts and out it comes?
The issue is with the sump removal rather than taking out the piston - I'd have to lift the motor or drop the subframe.... and I'm not ready for really heavy work
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Missing circlip on the end of the pin? :-\
Eg the pin holding the piston to the rod? How would that have happened? :-\
If we're certain this scoring happened when the car was running, before it was dismantled, that makes me feel a bit better. I was worrying it's something I did during the repair process :'(
Yeah. Pass... Manufacturing error?
I would bet money I don't have on it occuring well before you opened it up. And also that whatever did it has been "rubbing" against it for a long time rather than grinding/forcing against it for a short period of time. Aside from which you'd have heard it if you'd caused that much marking in a short space of time.
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also that whatever did it has been "rubbing" against it for a long time rather than grinding/forcing against it for a short period of time.
So a chance something could still be in there?
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I pressume it isn't mirrored on the opposing side of the bore?
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I pressume it isn't mirrored on the opposing side of the bore?
Let me run out and have a look :y
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I pressume it isn't mirrored on the opposing side of the bore?
Nope, just went out for another look, just that one side.
I filled the cylinder with WD40 earlier, and it doesn't seem to have leaked down at all, maybe that's a good sign.
Also interesting how the score is dead vertically straight on each side?
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Also interesting how the score is dead vertically straight on each side?
not really, the piston only goes up & down ;)
As suggested, idealy, you need the piston out to examine the piston ring grooves for crap or broken ring
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Hmm. The fact that there seem to be hundreds of marks all reaching various altitudes in the bore further backs up the theory that it is/was something floating around in the end of the wrist pin hole in the piston skirt thingamy.
Unlikely to be the wrist pin itself I would have thought as that would never have touched in the middle.
Have you got a higher res picture just out of curiosity.
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I'll upload one in a tick and post a link rather than embedding, so I don't screw up this page :y
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http://www.uk-chat.co.uk/bmw/bore.jpg
This is the image without being shrunk
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Ah it's not central to the pin then. But very nearly the same width as the aperture...
(http://i.ebayimg.com/00/s/MTIwOVgxNTMw/z/hYIAAOxyQfJThFti/$_1.JPG)
Also looks like a weird casting mark horizontally 1/3 the way down? The honing looks a bit healthier in the top of the cyl behind, but maybe that's camera focus?
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Actually, looking how far it is up the bore it could only have been something in the top ring :-\
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Not sure that I would worry about that :-\ vertical marks are finer than the lateral roughing marks (also present on adjacent bore), and both are still smooth enough to reflect the crown of the piston...
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Not sure that I would worry about that :-\ vertical marks are finer than the lateral roughing marks (also present on adjacent bore), and both are still smooth enough to reflect the crown of the piston...
To be honest - if we're sure it happened before I took it apart, then it's not so much the scoring we can see, that I'm worried about - as I think that's fine - it's more whether or not there's anything stuck in there likely to do more damage... :-\
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All well just put the piston to tdc and use a torch, there should be a tiny bit of play and give you enough clearance to see if there's anything still there?
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All well just put the piston to tdc and use a torch, there should be a tiny bit of play and give you enough clearance to see if there's anything still there?
Will certainly give that a go :y
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Does the piston move smoothly up and down the bore? Any knocks or creaks?
Thinking it could be a bit of wear in the conrod/crank bearing causing the piston to float against the bore under load... if that makes any sense :-\
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Does the piston move smoothly up and down the bore? Any knocks or creaks?
Thinking it could be a bit of wear in the conrod/crank bearing causing the piston to float against the bore under load... if that makes any sense :-\
Smooth as silk, I can turn the crank using just my hands on the pulley :y
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Does the piston move smoothly up and down the bore? Any knocks or creaks?
Thinking it could be a bit of wear in the conrod/crank bearing causing the piston to float against the bore under load... if that makes any sense :-\
Smooth as silk, I can turn the crank using just my hands on the pulley :y
So none of the rings are touching the bores then ;D :D ;)
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All well just put the piston to tdc and use a torch, there should be a tiny bit of play and give you enough clearance to see if there's anything still there?
Will certainly give that a go :y
Should be minimal slop across the block and zero along it...
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Hmm, well it's not top ring as that comes upto the dark line, might be something between the first and second.
See if it will polish out with some fine wet and dry with a bit of WD40 as lube as a starter
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Hmm, well it's not top ring as that comes upto the dark line, might be something between the first and second.
See if it will polish out with some fine wet and dry with a bit of WD40 as lube as a starter
I ran a little 1800 grit over it with some white spirit... gently...
To be fair there's nothing that can be felt by the bare finger / fingernail at all, it feels perfectly smooth
Do you think something could still be trapped between those rings, or is more likely that it's long gone?
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You compression tested this before you took it apart didn't you? If so it can't be that bad ???
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You compression tested this before you took it apart didn't you? If so it can't be that bad ???
No, I didn't - as didn't have any problems with oil burning or low power etc :-[
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I magnified your photo quite a bit and the mards don't look like scoring at all to me - rather like brush marks, oddly enough, as they are not perfectly strai8ght and dithered at the top of the bore, too. They are definitely on top of the honing marks. As already suggested, solvent and gentle abrasion could well remove them and whatever gets picj
ked up on the cleaning rag may give you a clue as to what caused them?
Ron.
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Are we SURE this happened with it running, and not since I took it apart?
Reason for asking:
I found this (below) photo, taken a few weeks ago, from after I took the head off, but, before I spun the crank far enough today, to fully lower the no4 piston (the one in question).
The wall looked like this:
(http://www.uk-chat.co.uk/bmw/bore2.jpg)
So you can see in this picture, immediately after taking the head off, the marks DONT appear to go all the way down, and only stop at where the piston had been sat? Or am I mistaken?
Would this not imply, that whatever is in there, caused the marks to go all the way down there today, when I turned it by hand?
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Also present on bore 6 :y
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You start your thread with 'bore damage'. I can't see any damage, just a slight marking (not scoring). You have your way of doing things and other people theirs. Personally, I'd put that back together and run it.
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You start your thread with 'bore damage'. I can't see any damage, just a slight marking (not scoring). You have your way of doing things and other people theirs. Personally, I'd put that back together and run it.
Well, what you waiting for? Pop over and put to back together for him. Sure you'd have it done in what, 20 mins? :D
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Hmm, well it's not top ring as that comes upto the dark line, might be something between the first and second.
See if it will polish out with some fine wet and dry with a bit of WD40 as lube as a starter
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Are we SURE this happened with it running, and not since I took it apart?
Reason for asking:
I found this (below) photo, taken a few weeks ago, from after I took the head off, but, before I spun the crank far enough today, to fully lower the no4 piston (the one in question).
The wall looked like this:
(http://www.uk-chat.co.uk/bmw/bore2.jpg)
So you can see in this picture, immediately after taking the head off, the marks DONT appear to go all the way down, and only stop at where the piston had been sat? Or am I mistaken?
Would this not imply, that whatever is in there, caused the marks to go all the way down there today, when I turned it by hand?
Looks like the marks go down to the top of the piston to me squire ???
As mark says... polish it out and re-spin it and you'll know.
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It isn't isolated to that one cylinder... ergo, unlikely to be debris related ::)
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You start your thread with 'bore damage'. I can't see any damage, just a slight marking (not scoring). You have your way of doing things and other people theirs. Personally, I'd put that back together and run it.
Well, what you waiting for? Pop over and put to back together for him. Sure you'd have it done in what, 20 mins? :D
How old are you? 30? I was stripping engines before you were born, lad, you're still shitting yellow. ;D
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You start your thread with 'bore damage'. I can't see any damage, just a slight marking (not scoring). You have your way of doing things and other people theirs. Personally, I'd put that back together and run it.
This! :y
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You start your thread with 'bore damage'. I can't see any damage, just a slight marking (not scoring). You have your way of doing things and other people theirs. Personally, I'd put that back together and run it.
Well, what you waiting for? Pop over and put to back together for him. Sure you'd have it done in what, 20 mins? :D
How old are you? 30? I was stripping engines before you were born, lad, you're still shitting yellow. ;D
You must be known all over the world for your scouse charm. :)
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You start your thread with 'bore damage'. I can't see any damage, just a slight marking (not scoring). You have your way of doing things and other people theirs. Personally, I'd put that back together and run it.
Well, what you waiting for? Pop over and put to back together for him. Sure you'd have it done in what, 20 mins? :D
How old are you? 30? I was stripping engines before you were born, lad, you're still shitting yellow. ;D
You must be known all over the world for your scouse charm. :)
Thank you :)
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You start your thread with 'bore damage'. I can't see any damage, just a slight marking (not scoring). You have your way of doing things and other people theirs. Personally, I'd put that back together and run it.
Well, what you waiting for? Pop over and put to back together for him. Sure you'd have it done in what, 20 mins? :D
How old are you? 30? I was stripping engines before you were born, lad, you're still shitting yellow. ;D
You must be known all over the world for your scouse charm. :)
Thank you :)
Its guaranteed if Crimestoppers is shown abroad...
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Have stripped and rebuilt loads of engines in my time - my advice if you can't feel scoring with your finger/fingernail, touch of wet 'n dry, and put it back together. :y
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Silly question, but could it be carbon from a build-up of burned oil in the gudgeon pin end-hole (not a very technical term, sorry) as a result of the turbo failure? If that is a possibilty, wipe it off and continue the rebuld, forgetting all about it..... 8)
Ron.
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Just to reiterate...
THIS 'WEAR' IS CLEARLY VISIBLE IN AT LEAST ONE OTHER CYLINDER BORE...
Whatever caused it is present across the engine, not confined to one cylinder.
Apologies for yelling, but everything thus far seems to be stuck on one bore.
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Just to reiterate...
THIS 'WEAR' IS CLEARLY VISIBLE IN AT LEAST ONE OTHER CYLINDER BORE...
Whatever caused it is present across the engine, not confined to one cylinder.
Apologies for yelling, but everything thus far seems to be stuck on one bore.
I think you must be looking at a different picture to the one I can see :-\
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Picture in reply #40 same vertical markings on bore 6...
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Picture in reply #40 same vertical markings on bore 6...
Sorry for lack of update had a bereavement today. Old and expected but still sad :(
Having cleaned no6 with just a rag it doesn't have the same marks, although the pic Al suggests does look that way
No4 almost polished out and isn't overly coming back with cranking
I will post pics as soon as I'm in a position
Big thanks to you all.
:y
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Sorry to hear that. Never a good time, however anticipated.
Markings may simply be a side effect of cranking the engine dry without causing any lasting damage :-\
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Sorry to hear that. Never a good time, however anticipated.
Markings may simply be a side effect of cranking the engine dry without causing any lasting damage :-\
Cheers mate. And I really hope so :y
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Surely the proof is in how the car runs despite these imperfections.
I'd just put it back together. It may run like a Swiss watch.
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I haven't read the full thread but I'm with Opti, Id just put it back together and see what happens....
Iv had worse than that on a Montego (yeah I know chalk and cheese but engines are engines) and it ran perfectly fine afterwards...
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Just to reiterate...
THIS 'WEAR' IS CLEARLY VISIBLE IN AT LEAST ONE OTHER CYLINDER BORE...
.....
Shhhhhhh! ::) ;)
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I polished it off as suggested, and, having turned it by hand, the marks don't seem to have come back / no new marks, so I'm going to put this down to a historic bit of carbon etc, and get on with the rebuild. I'm no longer so worried about it :y
I did have a think actually about what might have caused it. Some months ago when I had the inlet off for something else, I thought I dropped a backup washer into an inlet valve port. It turns out that I didn't - however in the process of looking for it, I poked about in each one of the inlet ports with a bore scope. These ports were all pretty full of carbon, so I wonder if I disturbed some, and this is what caused the marks in the cylinder.
Either way - onwards and upwards :y
Many thanks for all the replies :y
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I'm more interested in how it's happened? I don't recall seeing it before but then I didn't inspect the bores, and this one was close to the top before I gently spun the engine by using a hand on the pulley
Is it something that I could have done having turned one rotation by hand? Or must it have been like it before!
You can't feel it with a fingernail or finger. The car never used any oil before :-\
Put it back together and stop worrying.
This is what happens when you get too far into things