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From: Mrcheerful on 13 Jan 2010 09:51
Dave Baker wrote:
> "Mrcheerful" <nbkm57(a)hotmail.co.uk> wrote in message
> news:mak3n.25492$Ym4.18310(a)text.news.virginmedia.com...
>> martin wrote:
>>> On 13/01/2010 12:55, Mrcheerful wrote:
>>>> Adrian wrote:
>>>
>>>>> They can and do corrode and seize in place, possibly exacerbated
>>>>> by poor workmanship on replacement last time. It can be
>>>>> effectively impossible to remove them in situ if particularly bad.
>>>>
>>>> watch the video here of a proper job in situ:
>>>> http://www.youtube.com/watch?v=koghDoROFko
>>>
>>> Oh wow! How would that take in real time Mr C?
>>
>> That video is of the mercedes cdi engine which is well known for
>> stuck glow plugs, hence the purpose made kit. If access is good
>> then about half an hour per plug should be enough. But on some
>> engines you need to remove the injection pump before you can get
>> access, so every vehicle is different. The main point is that with
>> the right equipment and skill, glow plugs can often be sorted out
>> without removing the head and taking it to an engineering firm.
>
> Even as a perfeshunal enjinear it took a while to work out exactly
> what was going on in that video. However having Googled to see what a
> complete glow plug for one of those ought to look like I assume that
> the one in the engine broke below the top thread leaving just the
> bottom part in situ and the thread in the head still ok. The sequence
> then seemed to be drill, tap, screw in impact puller, pull out broken
> remains, ream hole for new glowplug.
> However if the old plug broke above the thread because it was rusted
> into place it would be an entirely different problem. So do they
> normally break below the thread or above it?

glow plugs can seize on their threads, or on the taper seat or just where
the hot bit pokes through
Mostly the hex is snapped off before the thread, often by amateurs using
manky spanners rather than a nice single hex socket and a T bar (which is
what I use and so far have not had one break, touches wood)

the design of the plug is such that the size reduces after the thread, so
accurate drilling can effectively release the thread on its own, the thread
is easily removed as a thin tube (as for standard broken bolt removal), then
removal of the rest of the plug is a pull out job after threading the inside
where the heating element goes.

I have taken out a few broken ones by welding a nut on the remainder and
turning that


From: martin on 13 Jan 2010 10:16
On 13/01/2010 14:55, steve robinson wrote:

> Most 'mechanics' now are fitters not mechanical engineers and wouldnt
> be able to perform small engineering tasks .
>
> How many garages actually rebuild/ re engineer engines now , i dont
> know of any , the just parcel them off to a specialist

Yes I agree with you there. I've rebuilt two engines totally (both top
and bottom ends) and had the blocks into a machine shop for rebore prior
to fitting oversized pistons/rings. The first took me a month because I
went very slowly, the second a week because I knew what I was doing.
Similarly for gearboxes, strip down, remove the broken parts, refurbish
and replace what's needed and rebuild.

Talking to modern car mechanics it's something they just don't do
anymore, whereas the old timers of my age it's more bread and butter.
Now it's drop the gearbox out, put in a refurb and ship old back to refurb.
From: asahartz on 13 Jan 2010 12:26
On Wed, 13 Jan 2010 15:16:38 +0000, martin <usenet(a)etiqa.co.uk> wrote:

>On 13/01/2010 14:55, steve robinson wrote:
>
>> Most 'mechanics' now are fitters not mechanical engineers and wouldnt
>> be able to perform small engineering tasks .
>>
>> How many garages actually rebuild/ re engineer engines now , i dont
>> know of any , the just parcel them off to a specialist
>
>Yes I agree with you there. I've rebuilt two engines totally (both top
>and bottom ends) and had the blocks into a machine shop for rebore prior
>to fitting oversized pistons/rings. The first took me a month because I
>went very slowly, the second a week because I knew what I was doing.
>Similarly for gearboxes, strip down, remove the broken parts, refurbish
>and replace what's needed and rebuild.
>
>Talking to modern car mechanics it's something they just don't do
>anymore, whereas the old timers of my age it's more bread and butter.
>Now it's drop the gearbox out, put in a refurb and ship old back to refurb.

Isn't that the case with most things these days? My father was a
TV/video engineer before he retired, and even 10 years ago was one of
the few left who could repair most faults, while other engineers just
changed a whole panel.

Years before that, my grandfather, who was a skilled toolmaker, would
look at what broke in his car, think it through, redesign it and machine
up an improved part!
--
asahartz woz ere
From: Cynic on 13 Jan 2010 14:30
On Wed, 13 Jan 2010 15:16:38 +0000, martin <usenet(a)etiqa.co.uk> wrote:

>On 13/01/2010 14:55, steve robinson wrote:
>
>> Most 'mechanics' now are fitters not mechanical engineers and wouldnt
>> be able to perform small engineering tasks .
>>
>> How many garages actually rebuild/ re engineer engines now , i dont
>> know of any , the just parcel them off to a specialist
>
>Yes I agree with you there. I've rebuilt two engines totally (both top
>and bottom ends) and had the blocks into a machine shop for rebore prior
>to fitting oversized pistons/rings. The first took me a month because I
>went very slowly, the second a week because I knew what I was doing.
>Similarly for gearboxes, strip down, remove the broken parts, refurbish
>and replace what's needed and rebuild.
>
>Talking to modern car mechanics it's something they just don't do
>anymore, whereas the old timers of my age it's more bread and butter.
>Now it's drop the gearbox out, put in a refurb and ship old back to refurb.

Purely as an idle question from a rank amateur - when drilling out a
glowplug or spark plug without removing the head, how much risk is
there of getting metal bits into the cylinder that causes damage as
soon as the engine is started after the repair?

I well recall my father dropping a single small washer into the open
throat of a carburetter while the engine was running, and the mess it
made of a cylinder lining, piston and cylinder head.

I would have thought that a small bit of swarf that fell into the
cylinder may well be practically impossible to spot and even less easy
to remove.

--
Cynic


From: Jethro on 13 Jan 2010 14:44
On 13 Jan, 19:30, Cynic <cynic_...(a)yahoo.co.uk> wrote:
> On Wed, 13 Jan 2010 15:16:38 +0000, martin <use...(a)etiqa.co.uk> wrote:
> >On 13/01/2010 14:55, steve robinson wrote:
>
> >> Most 'mechanics' now are fitters not mechanical engineers and wouldnt
> >> be able to perform small engineering tasks .
>
> >> How many garages  actually rebuild/ re engineer engines now  , i dont
> >> know of any , the just parcel them off to a specialist
>
> >Yes I agree with you there. I've rebuilt two engines totally (both top
> >and bottom ends) and had the blocks into a machine shop for rebore prior
> >to fitting oversized pistons/rings. The first took me a month because I
> >went very slowly, the second a week because I knew what I was doing.
> >Similarly for gearboxes, strip down, remove the broken parts, refurbish
> >and replace what's needed and rebuild.
>
> >Talking to modern car mechanics it's something they just don't do
> >anymore, whereas the old timers of my age it's more bread and butter.
> >Now it's drop the gearbox out, put in a refurb and ship old back to refurb.
>
> Purely as an idle question from a rank amateur - when drilling out a
> glowplug or spark plug without removing the head, how much risk is
> there of getting metal bits into the cylinder that causes damage as
> soon as the engine is started after the repair?
>
> I well recall my father dropping a single small washer into the open
> throat of a carburetter while the engine was running, and the mess it
> made of a cylinder lining, piston and cylinder head.
>
> I would have thought that a small bit of swarf that fell into the
> cylinder may well be practically impossible to spot and even less easy
> to remove.
>
> --
> Cynic

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 ....
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