[Vwdiesel] More Dasher?

James Hansen jhsg at sasktel.net
Tue Jun 19 02:27:07 EDT 2007

William J Toensing wrote:
> Finally got the head off today & what to my wandering eyes did appear
> was a crack in the block  where the right front head bolt goes in. I
> did not find any cracks where the other 11 mm headbolts screw into
> the block.  What I am thinking of doing is to get 12 mm studs of
> proper length instead of  12 mm head bolts, tap the block for 12 mm
> studs, & JB weld the stud into the right front block where it is
> cracked.  In following the discussion on VW headbolts there was
> discussion of using ARC racing headbolts or studs instead of the
> stock VW stretch bolts. Is there an online source for the ARC
> headbolts & studs?

  ARP 251-4701 for a Ford Cosworth fits all 12mm tdi through 1.6td.
Unsure about the 11mm, never done one.
Raceware has the 11mm studs however.

> I used an 11 mm tap to clean the threads when I replaced the
> headbolts before. I wonder if I made the holes too large when I used
> the 11 mm tap since I read some comment in the headbolt discussion
> that the VW factory headbolts were some odd ball size slightly
> smaller than 11 mm? 

no. You most likely missed some crud or oil at the bottom of the hole.
It's a clean, vacuum, brake cleaner, vacuum, blow gun kind of cleaning 
job.  No oddball sizes, just a straightforward metric threadform in a 
blind hole.
This is another advantage of using studs in blind holes.  you never 
crank the studs in with torque, you insert them with finger pressure 
only.  If they don't go in, there is an issue to deal with before you go 

  Are the factory 12 mm  threads & bolts a
> slightly different size than a standard 12 mm thread? In changing the
> threads from 11 mm to 12 mm, do the holes have to be drilled out or
> are the 11 mm holes large enough to accept the 12 mm tap.

Drill, then tap, but it will be hard to do well.  The crack will want to 
move open as you cut.

  Do you
> think JB welding the right front crack will work or am I wasting my
> time with that block? 

I would be skeptical it would work, and unless I had the only available 
block on the planet, would recommend finding another block..

  I had a local machine shop check to seer if
> the head was warped & they said no, but recommended it be surfaced. 

Sure.  But that's how they make money.
Ask the ice cream man if you need ice cream, you get more or less the 
same answer.  At least they were truthful about warpage, which is a 
bonus, but they will always want to "take a skim cut" to remove 
invisible gasket wear, which is pure BS.  It pretty much either needs 
it, or not.

> recall reading somewhere recommendations that VW diesel heads not be
> surfaced.

Yep, sort of- there's more to it than just resurfacing.  Unless you are 
willing to change valve stem length to compensate for the reduced head 
length. It's a job left to good head shops that do this stuff a lot. 
It's easy to get a head that you can't get thin enough shims for the valves.

  The head has surface cracks about a fingernail's width
> between the valve seats but I recall reading that practically all VW
> diesel heads have these cracks between the valve seats & these small
> cracks up to a fingernail's width do not render the heads useless.

Normal with age.  Peen shut if you want to, if not, leave them, they are 
mostly harmless.

> Again, where would I buy the 12 mm ARC racing studs? Or would you
> recommend I go a different route? Do you know the proper length? Do
> you have a particular ARC part number I should order? Also, do I need
> 12 mm hardened washers or will any washers do? 

They come with the studs usually.

I want to do the job
> right this time & not have to do it over again. 

That's what we all say.
Took the stock car to the track for a big invitational this weekend, 
forgot to take oil pressure along.  This will be teardown number three.
And i used to think I know what I'm doing too...


I am not an
> experienced engine rebuilder & the only engine I have rebuilt was on
> a Model A Ford, but the job was successful. 
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>  Vwdiesel at vwfans.com 
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