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Date:         Sat, 21 Mar 2015 15:12:30 -0400
Reply-To:     Michael <mbucchino@CHARTER.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Michael <mbucchino@CHARTER.NET>
Subject:      Re: Head stud testing
Comments: To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
In-Reply-To:  <BAY405-EAS1637731A52AB2C4E6757912A00F0@phx.gbl>
Content-Type: text/plain; charset=utf-8

Any difficult fastener; penetrant, hea

Sent from my iPhone

> On Mar 21, 2015, at 14:52, Dennis Haynes <d23haynes57@HOTMAIL.COM> wrote: > > For broken head studs I weld a nut onto it so I can grab it with a wrench maybe an impact. Then using an oxy-acetylene torch heat the case in the stud area to free the interference fit along with whatever super Loctite they use. One has to be careful not to break the stud down so low you can grab it.

> > Dennis > > > -----Original Message----- > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of thewestyman > Sent: Saturday, March 21, 2015 2:13 PM > To: vanagon@GERRY.VANAGON.COM > Subject: Re: Head stud testing > > Dennis, > > You are the best there is in Vanagon World. > > "If the heads are loose, the studs are stretching" I did not understand this. If the head is loose the bolts are still not tightened, I think, and thus nothing is stretching yet. But you must have meant it differently, I'm sure. > > The other thing; I have a real hard time taking studs out, never mind wanting to change them all anytime I would like to. I have an engine with a stud half of it broken, I can get to it to apply power to turn it, I can heat the block and the stud with a torch (oxy-acet), yet it wont' budge. > What is the most I can do to it? > > Regards, > Zoltan > > > -----Original Message----- > From: Dennis Haynes > Sent: Saturday, March 21, 2015 7:19 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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