I still do not completely understand the notion of machining heads. Also not sure exactly which part of the engine is classified as the heads. Excuse my laxk of understanding. Ive never worked in an engine before.

How much does it cost to get heads machined? What is involved in the process? When contacting a machine shop? Exactly what would I be asking them to do? If I say "yeah I need my heads machined? Are they going to understand exactly what I need or are their options involved? Technical details?

Also where can I find used newly machined heads for a D2 4.6?

 

you need to have you heads tanked, decked and valve guide seals replaced. should run you approx. $200.00 less if you shop around.

pix: before during after

 

I probably understand it somewhere in between what you know and what actually happens. Let's see how I do.

Essentially, when the engine overheats and the head gasket blows, it partly blows because the head actually warps in the heat. It bends a little bit. This makes a gap that the gasket can't cope with and your oil and water go to places they are not allowed.

After things cool down the head stays bent. I know it only moves 1000's of an inch, but it is then enough that if you simply bolted the engine back together with a new gasket in, there would be a huge weak spot, if not a huge gap, for the oil and water to be naughty again.

Any machine shop that has done car work will know what machining the heads involves. They put the head on a milling machine and take off the bare minimum of 'high' material to make the head flat again.

I'd be interested to know just how much they do warp by. I'm assuming the block can't wrap, as it's a much bigger mass of material. The smaller bit bends first, and by that time you have a duff engine, so the block doesn't get chance to warp.

Ok, that's what I reckon. Let's see what actually happens......

Edit. Just watched the video. I had no idea of the heating and cooling technique to straighten the head first. Can't believe he could pull it straight with just the leverage of a 6" spanner. Cool stuff.

 

Thanks guys for the explanation. So exactly what function do the heads serve? Or are they just essentially covers that protect the interior components of the engine? Ill have to do some research to see if there are any machine shops in my area.

Drowssap I sent you a PM.

 

Heads are housing the valves and Passages For fuel, exhaust, cooling, etc.

 

try this one: