Date: Mon, 23 Mar 2015 10:02:12 -0500
Reply-To: Kevin Duvernay <kduvey@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Kevin Duvernay <kduvey@GMAIL.COM>
Subject: Re: Head stud testing
In-Reply-To: <CA+az7_5qrwyo3PGcQK6vNYzdgccH=PE=xU+6f2m5obNE90KKMA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
I don't know if this would work for head studs, but I've snapped two
exhaust studs near the base (too close to grab with vice grips or weld a
nut on). I had good luck with both drilling them out (VERY carefully) up to
17/64ths one or two bit sizes at a time then tapping with a M8x1.25 tap -
the same size at factory original. Might be worth trying this before a
helicoil.... helicoil should be absolute last resort.
On Sat, Mar 21, 2015 at 3:07 PM, John Rodgers <jrodgers113@gmail.com> wrote:
> Just a couple of points. On case studs, when all else fails, they must be
> drilled out and helicoils installed. BTDT many times on aircraft engines.
>
> Re:diesels, new semi truck tractors are now getting 1,000,000 mile
> warrenties on the engines. I am sure there are some caveats to that but I"m
> sure the technology behind it is spilling over to automobiles. Things like
> sleeved engines. It's come full circle. Ford, back in the early '40's I
> think, built an engine with replaceble sleeves for about 18 months. Then
> some bright soul pointed out that would not be selling many blocks when
> they could just replace the sleeve in the block. Next year sleeves
> disappeared.
>
> John
> On Mar 21, 2015 2:41 PM, "Dennis Haynes" <d23haynes57@hotmail.com> wrote:
>
> > Maybe the term real Diesel is miss leading. I was referring to large
> truck
> > and medium speed industrial engines. These are built for long term
> > operation and permanent installation. Most get overhauled in place
> > including replaceable cylinders. Engines with cylinders cast in block or
> > "parent bores" are usually lower cost replaceable engines. Even the
> > Caterpillar C7 fits this class.
> >
> > These engines for years have required special coolants or additives to
> > prevent the micro bubbles. Many even have systems with the additives
> being
> > dispensed while operating the engine. For the C7 in my motorhome I used
> the
> > test the coolant every three months and add the stuff as needed. Now I
> use
> > the "Final Charge" which should last for 6 years or 600,000 miles with an
> > addition of an additive at the 1/2 life. With a system capacity near 20
> > gallons you don’t want to change coolant very year or two. I now use this
> > stuff in the Vanagons and it seems to work very well including improved
> > cooling. Takes me out of the coolant changing business.
> >
> > Dennis
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> > Of Tom Hargrave
> > Sent: Saturday, March 21, 2015 11:04 AM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: Head stud testing
> >
> > 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
> >
> > -----
> > No virus found in this message.
> > Checked by AVG - www.avg.com
> > Version: 2015.0.5856 / Virus Database: 4311/9339 - Release Date: 03/19/15
> >
>
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