Author Topic: warping head (Read 2316 times)

vegfuel · « **on:** December 12, 2007, 02:23:02 pm »

So as i was fiddling around with tranny linkages to my Rabbit. I had a guy I know help me by pushing in on the clutch after I hooked it up. I told him that I am going to take of the head pretty soon and do a rebuild.

He said that I should get the head "shaved" as it is aluminum and might warp when I take it off. He said that it would only cost me about $30.
He's only worked on gassers so I thought that I should consult someone here before I go ahead with this. What exactly does it do to the head? Does it just take off a certain amount of aluminum? Is it really necessary?

jimfoo · « **Reply #1 on:** December 12, 2007, 02:59:32 pm »

If it's warped it is necessary, but if you take the bolts out in the proper sequence, it won't warp from just removing it. A local machine shop could check it for you. They just take enough off to make it flat.

jtanguay · « **Reply #2 on:** December 12, 2007, 03:43:50 pm »

get it checked anyways. you never know, and it could mean you having to remove it again to replace the HG in the future.

if they need to remove a whole lot of material it gets more expensive as they need to line bore for the camshaft too... and only certain places can do that.

so do as jimfoo said and take the bolts out in sequence :wink: but i would recommend at least getting it checked.

Vincent Waldon · « **Reply #3 on:** December 12, 2007, 04:15:04 pm »

Because of the pre-combustion chambers it can't be "shaved" in the traditional sense with traditional tools... the hardened chambers will chew up the cutter head. This sets it apart somewhat from traditional gasser procedures.

With the proper equipment it can be done... probably best to find a shop with specific VW diesel experience.

Whoever looks at your head should start by measuring it to see how much warp is has... perhaps theres no need to do anything.

boosted_diesel_84 · « **Reply #4 on:** December 13, 2007, 11:37:01 am »

i work at a VW/ Audi machine shop, and every head iron or aluminum, no matter if its been over heated and blew a head gasket or not, should be milled, just due to the normal combustion pressures and heat cycles the head warpes some. it is always best any time a head is off to have it milled, it does not cost very much, like veg fuel said, its around $30 for a 4 cyl. head, and normally it only needs around 5 thousandths off to get it flat, plus having a fresh surface to seal on always makes the gasket hold better, because you want the surface as smooth as possible. the mill at the shop spins very fast and has a carbide cutter and has no problem cutting over the prechambers, it does it all the time and its fine, i can see an old rotary broach mill, which moves very slow and is very old might have a problem with it, so check to see what kind of mill the shop has. but milling a head is a very inexpensive way to be sure your headgasket job will hold for many years to come with out problems.
-Jack-

vegfuel · « **Reply #5 on:** December 14, 2007, 01:39:13 pm »

hey thanks for all that

Well I checked and my small town doesn't have the machinery for it but I can send it away south of me so it will cost me a little more than I anticipated :roll:

So do I need to take the head apart and just send the head or can I just take it off and leave the valves and everything in?

TDDrew · « **Reply #6 on:** December 14, 2007, 03:30:45 pm »

Last time I got my 1.6 head milled it costs as much getting 2 V8 heads because they have to remove the metal injector pucks and mill those sperately.

Quantum TD · « **Reply #7 on:** December 15, 2007, 01:26:35 am »

Conventional mills will cause problems as others have noted. The pucks are hardened nickel, and will pull out when hit by the blades of a mill.

The best bet for machining the head (with minimal warpage:under .006"), is to find a shop with a grinding mill. They use a sanding wheel to mill (kinda like a flywheel/rotor grinding wheel). There's a guy I know in CT (Kiwi) who does that and the finish is like a baby's ass, without having to pull the pucks.

BUT, if the warpage is large (greater than .006"), then you may have to have the head really worked. The surface isn't the only thing that warps when a head really overheats; the cam journals get warped too, and it often bends the camshaft. In which case, it'll need to be straightened. Also, if you mill off a lot, it's also a good idea to recess the valve seats and do a full valve job to accomodate the piston projection.

But, if it's running fine, it sounds like you're ok. Probably just a skim job to make a clean mating surface for the gasket.

Good Luck

TDDrew · « **Reply #8 on:** December 15, 2007, 01:31:51 am »

Quote from: "TDDrew"

Last time I got my 1.6 head milled it costs as much getting 2 V8 heads because they have to remove the metal injector pucks and mill those sperately.

Sorry, I am wrong. They remove the injector pucks and just drill out their recess as needed.
The other way to do it is with the giant belt sander looking device like Quantum TD is talking about.