Skimming a 300TDi aluminium head

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Griffith - 16 Jun 2007 13:06 GMT

I have a 300Tdi head which is seriously warped. Combine this with a
cylinder block which has had new liners installed and the top skimmed.

Can any one advise how much you can really skim off the head? The
manuals say you shouldn't do it. .................

I suspect that I will need the thickest gasket going and may be reseat
the valves further into the block, or skim the piston heads. Maybe
easier to buy a new block!

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icky - 16 Jun 2007 21:03 GMT

>I have a 300Tdi head which is seriously warped. Combine this with a
> cylinder block which has had new liners installed and the top skimmed.
[quoted text clipped - 5 lines]
> the valves further into the block, or skim the piston heads. Maybe
> easier to buy a new block!

What my local engine bodge shop does is re-cut valve seats then skim the
head with the valves fitted, this removes any valve head that may be
protruding. Don't know what this will do for longevity of the valves, butit
works for them.

Cheers, icky.

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Griffith - 17 Jun 2007 18:50 GMT

> >I have a 300Tdi head which is seriously warped. Combine this with a
> > cylinder block which has had new liners installed and the top skimmed.
[quoted text clipped - 16 lines]
>
> - Show quoted text -

Now that is a real bodgit. I always thought that steel and aluminium
had different cutting tools and this really makes me cringe. I wonder
if any body else has any thing better!

Griffith

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EMB - 17 Jun 2007 20:10 GMT

>> What my local engine bodge shop does is re-cut valve seats then skim the
>> head with the valves fitted, this removes any valve head that may be
>> protruding. Don't know what this will do for longevity of the valves, butit
>> works for them.

Skimming with the valves in place is a widely accepted trade practice.
Unless you're skimming outrageous amounts off the valves it causes no
problems whatsoever (and is much preferable to valves and piston touching).

> Now that is a real bodgit. I always thought that steel and aluminium
> had different cutting tools and this really makes me cringe. I wonder
> if any body else has any thing better!

It's not a bodge at all if you're skimming the head properly with a
surface grinder. The stones used for surfacing a head are generally a
universal type suitable for both cast iron and aluminium heads. The
biggest bodge is not hardness testing an aluminium head before surfacing
it - if it's gone soft it'll only ever give problems as it'll just
change shape when torqued down rather than providing a clamping force on
the gasket.

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Austin Shackles - 17 Jun 2007 21:08 GMT

>I have a 300Tdi head which is seriously warped. Combine this with a
>cylinder block which has had new liners installed and the top skimmed.
>
> Can any one advise how much you can really skim off the head? The
>manuals say you shouldn't do it. .................

How did it get warped?

I've heard it said that if the head's been seriously overheated, then it's a
waste of time skimming it.

Signature

Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------\
>> http://www.schlockmercenary.com/ << \ ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!

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Griffith - 18 Jun 2007 18:36 GMT

On 17 Jun, 22:08, Austin Shackles
<austinDITCHTHISFORBETTERRESU...@ddol-las.net> wrote:

> >I have a 300Tdi head which is seriously warped. Combine this with a
> >cylinder block which has had new liners installed and the top skimmed.
[quoted text clipped - 12 lines]
> >> http://www.schlockmercenary.com/ << \ ...and Kill them.
> a webcartoon by Howard Tayler; I like it, maybe you will too!

I bought it off e-bay at a low price and being 1500 miles away it was
not possible to check it before I bought it. The guy selling it said
it was okay. "Just slap it on" he said it was the first item that I
have bought on e-bay and I'm sure you have a good idea that I will now
buy anything with caution. ( What is it they say "buyer - be aware!" -
too flipping true, ouch!!")

The two centre valves are misaligned too the extent that there is
about 0.5mm on one side of the valves, the others are fine and I
suspect that it has been overheated. It is kind of taken up a copncave
shape. I am tempted to clamp it down after I have ground the valves in
but I am beginning to feel uncomfortable about it, so I may start
looking for another head.

Griffith of Gibraltar.

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Austin Shackles - 20 Jun 2007 07:40 GMT

>The two centre valves are misaligned too the extent that there is
>about 0.5mm on one side of the valves, the others are fine and I
[quoted text clipped - 4 lines]
>
>Griffith of Gibraltar.

If it's had a cambelt go the valves might be bent, worth a check. Sorry to
say that it sounds iffy. You can machine the head to flatten it but not
much. take too much off it and even with a fat gasket the valves can hit
the pistons.

The reason cited for not machining ones that have got seriously hot (and
we're talking engine-seizing hot, here) is that the alloy is heat-treated
and getting it too hot softens it. I'm not enough of a metallurgist to know
if that's bullshit, although it was a reasonably reputable lot that told me.

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Griffith - 28 Jun 2007 22:27 GMT

> >The two centre valves are misaligned too the extent that there is
> >about 0.5mm on one side of the valves, the others are fine and I
[quoted text clipped - 20 lines]
> >> http://www.schlockmercenary.com/ << \ ...and Kill them.
> a webcartoon by Howard Tayler; I like it, maybe you will too!

Having had a closer look at it, it would appear that the head gasket
had blown between pistons two and three, also there are small cracks
coming away from all the pre-heaters. The valves are perfectly
concentric when I am trying to grind them in. I am 80% on the way to
throwing it in the bin but I will take it to a specialist tommorrow in
Spain, trouble is my technical Spanish is not that good and they know
it and take advantage, its a laugh really. I have already asked them
for a price for a new head - 1200euros!

Tony

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Colin Reed - 29 Jun 2007 08:22 GMT

>...I've already asked them for a price for a new head - 1200euros!
>
> Tony

Island4x4 in the UK do brand new 300Tdi cylinder heads for ?269.99 +
?20 delivery to Spain. Don't know how many Euros that is but I guess
it's a lot less than 1200.

http://cgi.ebay.co.uk/LANDROVER-DISCOVERY-DEFENDER-300TDI-NEW-CYLINDER-HEAD_W0QQ
itemZ150073612597QQihZ005QQcategoryZ31348QQrdZ1QQcmdZViewItem

Colin
www.REEDX.net/landrover

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Dougal - 29 Jun 2007 14:38 GMT

>>...I've already asked them for a price for a new head - 1200euros!
>>
[quoted text clipped - 8 lines]
> Colin
> www.REEDX.net/landrover

Turner Engineering also have some but complete with valves, springs
etc.. Obviously a bit more pricey but a 'drop on' job.

http://turner-engineering.co.uk/html/specialoffers.html

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