Thanks guys will apply this knowledge to my replacement engine with its
unknown maintenance history.
Rick

On Sat, Mar 21, 2015 at 11:03 AM, Tom Hargrave <thargrav@hiwaay.net> wrote:

> Real diesels? Ford specifically had the head erosion problem, caused by a
> design flaw that causes micro-bubbles to pop against the wet side of the
> head and erode the aluminum. Mercedes and Cummings (used in Dodge trucks)
> "real diesels" don't have the problem. But like any other marketing
> opportunity, snake oil vendors have jumped on the opportunity to sell even
> more engine additive crap to us that we don't need!
>
> As far as a VANAGON stud tester is concerned - the right answer is to not
> re-use them. But if you have to re-use them, inspect for corrosion and
> measure the overall length. If the studs have stretched past their service
> length you throw them out.
>
> Thanks, Tom Hargrave
> www.kegkits.com
> www.stir-plate.com
> www.towercooler.com
> www.grow-sun.com
> www.raspberryproject.com
> http://goo.gl/niRzVw
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf
> Of Dennis Haynes
> Sent: Saturday, March 21, 2015 9:20 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Head stud testing
>
> The Vanagon head stud application is a bit unique. Due to the different
> materials in the case, heads, cylinders and the studs themselves thermal
> expansion becomes the real problem. As designed, properly installed the
> studs actually stretch and get turned into springs. In addition to this
> stress they also get attacked by corrosion or worse erosion. Yes, these can
> suffer the same effects as happens in diesel engines. Micro bubbles form in
> the coolant and combustion impulses make vibrations that when these bubble
> break some metal goes with them. Real diesel engines use special
> antifreezes or additive systems to combat this. Ford learned the hard way
> with the power strokes years ago as this actually began putting holes in
> the cylinders.
>
> Whenever doing head work you want to do a test installation and make sure
> all the studs can torque up to 41 ft. lbs. without excessive twisting. Ones
> that keep twisting and snap back more than say 1/16 turn are probably no
> good. If the engine was severely over heated it is probably best to replace
> them all. I also believe in replacing the head nuts or at least cleaning
> the threads with a high quality tap. Any thread friction will affect the
> final clamp load after torqueing. This is why many critical applications
> now torque to some lower number and then add some number of turns. This is
> also used for applications where the fastener is being torqued to yield
> like some rod bolts.
>
> If the engine is together and running it may be best to don’t try to fix
> what is not broken. If you have trouble with combustion gasses getting into
> the cooling system the first step is to check head torque. I have fixed
> many of these over the years this way. Keep in mind that except for
> incorrect installation if the heads are loose, the studs are stretching. A
> broken stud always means head removal and possible cylinder removal. If the
> stud breaks low it is engine out, apart, and off to a machine shop with
> some good milling equipment.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Richard Koller
> Sent: Saturday, March 21, 2015 8:17 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Head stud testing
>
> Dennis/List,
> I noticed that you have mentioned testing head studs a couple times on the
> list recently. I have an engine with a snapped head stud that ambushed me.
> This engine was maintained properly with regular coolant changes etc no
> overheating ( at least in my hands ) ran very well. Anyway, I have an
> interest in preventing a recurrence of this but I don' t know how to go
> about testing head studs. What's the procedure that is recommended.
> Thanks
> Rick Koller
>
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