# Proper way to check head/block for flatness?



## FastLapRSII (Jul 15, 2001)

So I'm replacing my headgasket (again) after 300 miles, due to vicious coolant leak. I reused my headbolts(yeah that's been covered), but I have new ones now.

The headgasket shows now signs of failure, but it's leaking like a seive. The head was just resurfaced 300 miles ago, but could it be warped already due to the reuse of the headbolts? It NEVER got hot.
I'm guessin' I need a precision machined straightedge and feeler gauges. How do y'all do it?


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## speed51133! (Aug 5, 2002)

*Re: Proper way to check head/block for flatness? (FastLapRSII)*

take off the head and put it on a granite slab. use feeler gauges to see if its warped. bently says the allowable warpage.
use a straight edge and feelers for the deck of the block.


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## Mr. Tickles (Jul 25, 1999)

*Re: Proper way to check head/block for flatness? (speed51133!)*

if you don't have access to a marble flat, you can use plate glass as your flatness standard. you can also use a precision rule, but a flat will give you a better idea as to the flatness of the head.


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## A1Rocco (Oct 6, 2001)

*Re: Proper way to check head/block for flatness? (Mr. Tickles)*

A steel straightedge from your local hardware store should do. Check the head across the mating surface in 3 directions along the cam line, and diagonally from corner to corner. Then flip it over and chack the cam bearings for alignment by carefully placing the straighedge in the bearings and rocking it back and forth. It shouldn't rock but a little bit is OK.


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## Vdubs (May 16, 2001)

*Re: Proper way to check head/block for flatness? (FastLapRSII)*

I use a precision flat block with sanding discs stuck on, it makes them dead flat and only removes the minimum of material, after one pass over you can see where it's not flat, no measuring ever needed. We do it on all removed heads and intake manifolds. 
A straight edge is the usuall method for checking but they're expencive and don't fix anything, you would be better off just getting it machined then you know it's good.


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## spitpilot (Feb 14, 2000)

*Re: Proper way to check head/block for flatness? (Vdubs)*

After you're sure head/block are flat...use "Copper Coat" gasket sealer on both sides of head gasket. I've used this stuff you eons and never had a leak! Fine suspended copper particles in sealant seem to flow into imperfections and really do the job, and also should help heat transfer between block and head!


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## gearhead455 (Oct 30, 2001)

*Re: Proper way to check head/block for flatness? (FastLapRSII)*

Make sure :
The head is clean
The block is clean
The head is flat
The bolts are torqued
The bolts are torqued in sequence


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## FastLapRSII (Jul 15, 2001)

*Re: Proper way to check head/block for flatness? (gearhead455)*

I think I found the root cause of my headgasket failure. I read another thread about oil in the bottom of the headbolt holes becoming trapped under the bolt tip and preventing full tightness. 
Well I ran the bolts to the bottom of the holes and sure enough, oil squirts out around the threads of the bolt the two places it was leaking. 
I can't get a 0.1mm feeler gauge under the head on a piece of glass, and the deck of the block is straight too. I might have to forgo the copper kote this time.
Thanks for the help peoples.







http://****************.com/smile/emthup.gif 
quote:[HR][/HR]Make sure :
The head is clean
The block is clean
The head is flat
The bolts are torqued
The bolts are torqued in sequence
[HR][/HR]​Yeah, I did that the first time.


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## Vdubs (May 16, 2001)

*Re: Proper way to check head/block for flatness? (FastLapRSII)*

Last time i saw that it split the block like cracking a nut, hope you got lucky. http://****************.com/smile/emthup.gif


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## Jetta2dr (Feb 19, 2001)

*Re: Proper way to check head/block for flatness? (Vdubs)*

It costs me $9.50 to get my head checked for warpage and cracks at the local machine shop.


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## sixteenvalve (Jun 13, 2002)

*Re: Proper way to check head/block for flatness? (Jetta2dr)*

quote:[HR][/HR]It costs me $9.50 to get my head checked for warpage and cracks at the local machine shop.[HR][/HR]​








Usually they will check them for free!!


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## vdubn4x4chik (Jun 27, 2002)

*Re: Proper way to check head/block for flatness? (Vdubs)*

We've broken a John block by hydraulicing the bolt like that too.... gotta be careful with stuff like that.


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