[88runnasr5]

Okay I friend of mine blew his motor in his 06 passat found a deal on a motor with 60k on it, the guy pulled the head off to inspect it.
I told him hes looking at machine work now and he thinks he can just throw a new hg on and call it good.
Am I wrong in thinking that or can he get away with just doing the hg and throwing the head back on?

 

[Wilson]

You're wrong. Heads only require machining if they are warped. Since it is off it may be worth getting checked out though, before putting it back on.

 

[a1racer]

What he said ^

 

[88runnasr5]

You're wrong. Heads only require machining if they are warped. Since it is off it may be worth getting checked out though, before putting it back on.

Okay maybe I worded it wrong I didnt mean to say resurfaced but atkeast checked out, mainly because its an aluminum head and dont they warp to the block?

 

[Wilson]

No, everything is decked and true upon initial assembly. Warping is the result of over heating.

 

[a1racer]

It wouldn't hurt to put a machinist straight edge on it before throwing a new head gasket. Never know with used motors.

 

[88runnasr5]

Alright thanks for the replys, never had to do a hg on a motor that was not from a overheated motor so iv just always taken it to the machinist.
Guess its up to him kf he wants to spend the extra money on it taking a chance.

 

[Wilson]

A machine shop will just use a machinist's straight edge.

 

[iniviate]

stop giving advice about things you're not sure about...

 

[88runnasr5]

stop giving advice about things you're not sure about...

Ill stop giving advice about things I dont know about when all those awesome motor shows explain it in detail.:flipoff2::

 

[Dookey]

You're wrong.

Damn. Beat me to it.


PS.... I didn't read this thread.

 

[Wilson]

Damn. Beat me to it.


PS.... I didn't read this thread.

I wa gonna say it anyways too :flipoff2:

 

[88runnasr5]

Damn. Beat me to it.


PS.... I didn't read this thread.

yeah yeah :flipoff2:

 

[bdkw1]

The head was strait till you pulled it off. If you machine it in the unclamped state you cam journals will not be in line any more. If it is less than .005 out run it. More than that , go find a strait head and use it. Otherwise it will start eating cam bearings.

 

[dragrcr65]

Straight edge and feeler gauges. Don't be stupid, if it was fine and not taken apart like an idiot the head is fine.

 

[sjracer]

The head was strait till you pulled it off. If you machine it in the unclamped state you cam journals will not be in line any more. If it is less than .005 out run it. More than that , go find a strait head and use it. Otherwise it will start eating cam bearings.

you just contradicted yourself.......

using the logic you stated in your first sentence, any head will be straight till it's pulled back off. so, how are they supposed to "go find a strait head and use it"?


FWIW: if a head is taken off properly, if it checks out with a straight edge it can be re-used indefinitely. this is why the MFG's have disassembly procedures. I have had many, many cylinder heads machined to remove the affects of electrolysis or small imperfections without a single camshaft problem......ever.

 

[bdkw1]

you just contradicted yourself.......

using the logic you stated in your first sentence, any head will be straight till it's pulled back off. so, how are they supposed to "go find a strait head and use it"?

Over heating them putts stress into the head. When you release the clamping load from them they find a new shape and release that stress. Measure the cam journals for concentricity before un-bolting it and after, that will really tell you if the head is usable.

If the head is more than .005 out, there is no guaranty that bolting it back down will pull them flat enough to make them seal again. You can resurface it to make it seal, but then your cam journals will not line up.

This is why I said, go find a flat unsurfaced head and use it.

 

[Landslide]

If your engine uses torque to yield head bolts, you need to replace them too.