exhaust stud repair

[billmongold]

ive heli-coiled them already and they didnt wanna stay in. ive been looking at heli-coil products online and i found little threaded bushings (like a solid heli-coil, not a coil of wire) called e-z loks. seems pretty solid, the isd is 8x1.25 and the od is 12x1.75. seems like it would hold pretty well since the od is so large and coarse (deep threads) plus, they're coated inside and out with red loctite (they say up to 300 degrees f.) any opinions/expierence?

 

 

http://www.grainger.com/Grainger/EZ-LOK-Self-Locking-Thread-Insert-4ZE42?cm_mmc=GoogleBase-_-Fasteners-_-Thread%20Insert-_-4ZE42&ci_src=14110944&ci_sku=4ZE42

Edited May 24, 2011 by billmongold

[Starfighterpilot]

ive heli-coiled them already and they didnt wanna stay in. ive been looking at heli-coil products online and i found little threaded bushings (like a solid heli-coil, not a coil of wire) called e-z loks. seems pretty solid, the isd is 8x1.25 and the od is 12x1.75. seems like it would hold pretty well since the od is so large and coarse (deep threads) plus, they're coated inside and out with red loctite (they say up to 300 degrees f.) any opinions/expierence?

 

 

http://www.grainger.com/Grainger/EZ-LOK-Self-Locking-Thread-Insert-4ZE42?cm_mmc=GoogleBase-_-Fasteners-_-Thread%20Insert-_-4ZE42&ci_src=14110944&ci_sku=4ZE42

 

See this recent heli coil repair link for what your options are.

 

http://www.starquestclub.com/forum/index.php?showtopic=117519

 

The exhaust studs get A LOT HOTTER than 300 deg.

 

For What It's Worth.

 

KEN

[Blue]

Hmmmm, timeserts....

[billmongold]

timeserts seem pretty good, but the issue is that the one hole is tapped for a 10mm stud. the drill and tap for the timesert doesnt seem like its large enough for hat hole. only one is 10mm, the rest are 8mm, but it seems like it will pose an issue. and of course the 10mm stud is the most rearward. anybody know if you can use the 8mm id timeserts on a tapped 10mm hole? id pay way more than 55 bucks (for the timesert kit) for my dumb exhaust manifold to quit loosening up.

[billmongold]

or am i gonna hafta drill the manifold for 10mm studs? i really dont hafta get a bunch of thin 10mm nuts. i also dont feel like modifying every head gasket from here on out. its hard enough to tighten this thing up with 8mm studs.

[holeysocks]

Why not go to SAE studs since they are much easier to find??

[Shelby]

i had one head that was already fubar'd real bad and drill'd off center and oval shape'd , what i end'd up doing was useing my drill pres i drill'd the hole to except a 10 mm bolt and then center drill'd a 10mm bolt thread'd it to 8x1.75mm and loc tite'd it into the head,, place'd the bolt into the head cut it off flush after it was loc'd in place , now i had a full length steel thread hole to hold that #4 exh stud , that was years ago , haven't heard of any problems from it

 

VW bugs use'd to have brass incerts to repair thread holes,,they also had studds that were larger on the one end and 8 mm on the nut side , their alum blocks had a lot of trouble with heat cycle cracks and threads pulling out after many miles ,,now this is going back a number of years

[Shelby]

http://www.1800vw.bi...m/savers_1.html

 

item #18

 

also notice these products are made for alum repair not iron

Edited May 25, 2011 by Shelby

[Metric-man]

Keenserts recommended by Alcoa (aluminum co.)

 

http://alcoafastener.thomasnet.com/category/general-purpose

 

http://www.newmantools.com/kee.htm

[Shelby]

see once you start looking there are lots of choices

[billmongold]

who has actually used any of these? personal opinions from expierence?

[Blue]

I've used helicoils. Work great if you do it right:

drill out hole, THEN cut your thread and install coil.

But I hear the timeserts are waaaaay better.

[Shelby]

we did tons of VW work years back and have use'd a lot of the things on that one page , plus at one time or another almost every thread repair device known,,even some like liquid metal that actualy remade threads that were pull'd out ( that work'd less then ideal )

 

heli coil products are fine and work great ,,you just need to understand that in an alum bolt hole you need twice the thread deepth that iron does,, so a 5/16" deep iron thread incert is not going to have enought threads in the alum to hold for long,,,you need at the least two heli-coils per hole

also if need'd you can find studs with longer thread ends on the short side ,, actualy if they had had more threads into the head the odds are the threads would have never pull'd out in the first place

[Metric-man]

who has actually used any of these? personal opinions from expierence?

 

Keenserts are used by Aircraft technicians, so a higher standard is presumed.

I didn't even know they existed until I was contemplating the problem as you.

I was informed of them by a seasoned mechanical engineer/ welder,(user name = welderwiz)

and he showed me his use of them on his 87 conquest's exhaust manifold.

This was 2003, and he has since sold the vehicle and the current owner has not experienced any regrets.

 

My opinion of welderwiz, is one of he is the type of person that would do things right the first time.

 

I am the type of person, that likes to learn from others mistakes, not just my own.

 

I still have not repaired the cylinderhead in question because it was used clearwater,

but I have it as a spare, I instead bought a new AMC in the GP forum.

 

Helicoils as Shelby suggests, are less expensive and will work.

 

Mitsubishi I believe learned from their pass designs and now uses a larger stud in the 4B11.

10mm instead of 8mm.

[billmongold]

id go to a 10mm stud... but the problem is modding the gasket cleanly and the bigger problem is getting a 17(?) mm nut to tighten up. there really doesnt seem to be space for them. the 13's are hard enough if im not using my snap-on 0 offset box end.

[Shelby]

the real trick with heli-coils is geting two of them in the hole and then useing a stud with longer threads , the oem studs do are not long enought to pull against enought alum to hold under stress of heat expantion,, thats why the exh gaskets are thick and can cursh and retain their shape , but there is a fine line between holding and pulling too much

 

over tourqe the stud nut and it will deff pull threads once it expands

[billmongold]

just ordered up my timeserts.