Vin # and plastic head dowels

[Ean Austral]

Gday All,

I remember reading a thread where someone posted the vin # where they changed the head dowels on the TD5 from plastic-to-steel.

Does anyone remember the thread or have the numbers im talking about...

Dad has a 2004 model D2a and has been told at he's next service.160k he should get the head done just incase the head has moved..

If someone can point me to it or has them would really apprieciate it.


Thanks and Cheers Ean

[Narangga]

Here Ean, was looking at it last night!

http://www.aulro.com/afvb/technical-chatter/117307-one-slipped-through-3.html#post1374166

[Ean Austral]

Thanks Stuuu,

after reading all that it seems that overheating is still the killer..

I know that hasn't happened to Dads so will try and convince him not to stress...Am sure he will start get some warning before the gasket goes..


Cheers Ean

[Tombie]

Its actually quite common, several years seem to have the plastic dowels.

There is no - reliable - vin range..

[BIG O]

Everyone LR mechanic I speak to tells me that after 03 they have steel.

[Disco EMU]

I was under the assumption that the plastic dowels were only there to help guide the head back onto the engine block ... it's the bolts that hold the head in place.

Happy to be corrected?

[Pedro_The_Swift]

True enough,,
but if the bolts come loose the head movement soon wears through the plastic---

[Urban Panzer]

True enough,,
but if the bolts come loose the head movement soon wears through the plastic---

So the underlying problem is just that, not the plastic dowels.

Maybe a periodic torque check of the headbolts, or even replacement would have been a better idea in the service schedule.

[Pedro_The_Swift]

Is there any reason this is not done?
is it detrimental to the gasket?

[Ean Austral]

Am sure I read somewhere that the head bolts cannot be re used or re tightened...This always never made sense to me, but just assumed they were some type of bolt that may have been heat affected by the different metals they went thru/into..

Surely even if you replaced them 1 by 1 then its got to be a better option than the head gasket failing..

Something for someone who is not far from changing a head gasket to try..Makes sense to my small brain..

Cheers Ean

[Urban Panzer]

Am sure I read somewhere that the head bolts cannot be re used or re tightened...This always never made sense to me, but just assumed they were some type of bolt that may have been heat affected by the different metals they went thru/into..

Surely even if you replaced them 1 by 1 then its got to be a better option than the head gasket failing..

Something for someone who is not far from changing a head gasket to try..Makes sense to my small brain..

Cheers Ean

Thats correct, the reason being is because they are know as "stretch" bolts, as they actually stretch in length when torqued down, my post was a bit way off tbh as its not the done thing, but "if" you was to replace one at a time, who knows how effective it would / could be. :angel:

[justinc]

Torque to yield is just that, the bolts are of a specific material, length and diameter etc to be in the yield range of their tensile strength. This range is followed by the plastic deformation range, which is permanent failure, with a change in relaxed length, a removal of tensile strength for the unit itself.

This is why they cannot be re used or retensioned.

Basically, they are designed to act as a 'spring' to continue clamping force at a steady state.

High thermal or tensile loads outside the materials design strangth will render them useless.

JC