Td5 intake manifold.

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Originally Posted by d2dave

If the Td5 engine has the combustion chamber in the piston like a Tdi, and looking at RAVE this appears to be the case, machining the head makes no difference to the head gasket thickness.

You just check what the old gasket was and replace with the same.

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Can you explain why this is the case? Seems weird to me.

The gasket thickness is to allow for piston protrusion above the top of the block. Machining the head has no effect on piston height.

And according to RAVE the head should not be machined, although I believe that some have done it.

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Originally Posted by d2dave

The gasket thickness is to allow for piston protrusion above the top of the block. Machining the head has no effect on piston height.

And according to RAVE the head should not be machined, although I believe that some have done it.

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RE Gasket thickness, correct...

http://www.aulro.com/afvb/technical-...thickness.html

However, plenty have had the head skimmed with no ill effects :)

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Originally Posted by Will Wallace

Jason,

What are the crucial measurements that need to be taken and what are the tolerances?

I assume that one would be piston protrusion?


Cheers
Will

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When you get the head shaved, find out by how much, and compensate with the gasket accordingly.

Cheers,

Jason

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Originally Posted by Jason789

When you get the head shaved, find out by how much, and compensate with the gasket accordingly.

Cheers,

Jason

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Jason. I assume what you are saying is that if .010 inch is removed from the head then use a .010 thicker gasket, yes?

It's also to compensate for the valve to crown clearance Dave, not just crown protrusion.

Usually a skim wont cause an issue if its never been machined before but it depends which side of "erring" it ended up with when the original gasket thickness was selected.

My research tells me that no more than .009 thou is the max that can be taken off a Td5 head. With this amount the valves should be ok.

My 20 years in engine building tells me it's a mistake that is still made.

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Originally Posted by LOVEMYRANGIE

My 20 years in engine building tells me it's a mistake that is still made.

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So which is the mistake. Taking any off or being able to take more than .009

The .009" you take off the head moves the valve face .009" closer to the piston crown unless you recut the valve seats to adjust the valve face protrusion from the head face back to its original measurement.
The overall clearance you're measuring is the crown to valve face and this is where the head gasket thickness comes in.