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From: Mrcheerful on 13 Jan 2010 20:13
Culex (The Infamous Culex) wrote:
> On Jan 13, 8:19 pm, Ian Jackson
> <ianREMOVETHISjack...(a)g3ohx.demon.co.uk> wrote:
>> Was that airline (used several times) a blower or a sucker? It didn't
>> seem like a sucker to me.
>
> The last operation seemed to use a vacuum hose as it was inserted in
> the hole formerly occupied by an injector; the tubing was also rather
> thicker than that of the airlines I use..
>
>> It would be wise to use a miniature inspection camera to check inside
>> the cylinder, to see if any swarf and other crud was lying inside.
>
> Could ants be trained to remove any swarf that got into the cylinder?
>
>> Finally, I would flood the top of the cylinder with thin oil, disable
>> ignition (how, on a diesel?), put a rag over the open glowplug hole,
>> and crank the engine for a few seconds. That should get rid of any
>> remaining crud (via the valves or through the hole).
>
> As I doubt that thin oil would wash out a bit of swarf stuck between
> the cylinder wall and the piston, might it not be a sensible
> precaution to add some thin oil via the injector hole before the
> process was started?
>
> Of course, this would mean that the ants would also have to be trained
> to swim.
>
> -- -
>
> Culex -- the Infamous Culex

the only time that anything can get into the cylinder is after the removal
of the remains of the glow plug, the only operation done then is to use a
reamer to clean coke from the bore of the hole, some thick oil is put on the
reamer first, even if some coke does get into the cylinder at this stage it
would do no damage, bits of coke are in the cylinder in any case during
normal running and fall off and go out through the exhaust on a regular
basis.


From: Duncan Wood on 14 Jan 2010 04:05
On Wed, 13 Jan 2010 21:07:22 -0000, Cynic <cynic_999(a)yahoo.co.uk> wrote:

> On Wed, 13 Jan 2010 20:19:09 +0000, Ian Jackson
> <ianREMOVETHISjackson(a)g3ohx.demon.co.uk> wrote:
>
>>> Very high ...
>
>>> even a speck, milligrams, could get stuck on the valve seat and lead
>>> to it burning ... as another poster suggested, when carrying out this
>>> procedure, it's a good idea to put the cylinder in question to TDC to
>>> close the valves and shield the cylinder wall ... but the risk still
>>> remains. Another trick is to smother the area in grease in the hope it
>>> will catch any swarf, but you now what sods law is like ....
>
>> Was that airline (used several times) a blower or a sucker? It didn't
>> seem like a sucker to me.
>
>> It would be wise to use a miniature inspection camera to check inside
>> the cylinder, to see if any swarf and other crud was lying inside.
>
>> Finally, I would flood the top of the cylinder with thin oil, disable
>> ignition (how, on a diesel?), put a rag over the open glowplug hole, and
>> crank the engine for a few seconds. That should get rid of any remaining
>> crud (via the valves or through the hole).
>
> How much gap is there between a piston and the cylinder wall? ISTM
> that if a small metal filing were to get into that gap and sit on the
> top piston ring, it may well escape all the above methods, and become
> dislodged only with the detonation of the first power stroke.
>

There's a commonly used technique in manufacture called thermal deburring,
if it's a thin bit of swarf then it'll be an ex bit of swarf.

> The question really I suppose is whether the risk is low enough to be
> worth the saving (and risk) of removing the head. Head removal in the
> only cars I have ever worked on was a quick and easy job, but a look
> under the bonnet of a modern car suggests that it was designed by
> someone who was a master at both jigsaw puzzles and tetris ...
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