So after ripping the threads out of the block (valve cover bolt) I have been attempting repairs. The Permatex is not drying hard enough and then crumbles if I torque it. Have tried with higher/lower amounts of each, more blue accelerant, etc... I can only think that the metal(block) is too cold (metal at 43 in garage) and is inhibiting the reaction. So now what? The hol;e is now drilled out and very un-uniformly shaped. I was thinking of having someone "fill" the hole with weld,retap and add Permacoil. Then thought....has anyone tried that using JB Weld as a filler and then drilling/tapping it?

Help your fellow DIY screw up.

 

How much is it drilled. There are two options, a heli-coil is a permanent solution. Second would be a Keen-sert. Do you know what diameter you drilled it to? The diameter that the hole is now will dictate the solution. Don't do any more to it until you have a good plan forward. (I don't like JB Weld for these typs of problems)

 

Have you considered using a product called alumiweld, or something like that? I've seen it advertised on TV and appears to work really well on aluminum, just using a regular propane torch, after thorough cleaning, and is claimed to be much harder than aluminum.

 

I would not trust anything other than repairing with a heli-coil kit.
Inserting a heli-coil puts stainless steel metal threads back in the hole and you know immediately whether it will hold or not.

http://www.emhart.com/products/helicoil.asp

 

I agree, and the reason I mentioned a Keen-sert is because I think it uses a slight larger hole for a given thread size than a heli-coil, such that if your holes are too big for a heli-coil there may be another permanent solution available. Measure the hole size.

 

Hey, on the positive side, you now have more of a reason to upgrade your heads.

 

Thank you gentlemen....I appreciate all of your input. I finally decided on the following:

I am going to fill the bolt hole with JB Weld and allow it to cure. Then I plan on drilling it and tapping it, then placing a Perma Coil (Same as Helicoil) in so as to provide steel threads instead of epoxy. As the valve cover bolts are "non critical" I figure this may work very well. Just need to be able to put 106 Lb inches on the torque wrench. It states that JB Weld is good up to 600 degrees which is more than enough.
Ideally it would have been best I think (yes, yes nwdanner..."new heads!") to have the hole filled with Aluminum weld, but I understand it is very tricky as the head could melt if not done correctly, compunding things. I have heard of "Alumiweld" too but not much else. I really would have needed to remove the head to fix it using weld and that would have necesitated obvious increase in work, something I was unwilling to do. So let's see. I 'll let you know how it all turns out. I just went out and checked on the curing process and it is moving quite slowly........I think the cool metal of the block and near freezing temps are slowing the chemical process.....I just hope it works.

 

suggest using a hair dryer, set on low and putting a fan on the area to facilitate the curing process, which is obviously very critical before attempting the next step of drilling.

 

I manufacture drilling equipment and have had a lot of experience with thread repair.
J B Weld will not work for this kind of application - it's a great crack filler but not a good thread repair option.
Your best bet for a permanent / professional repair is to use a thread insert. You’ll have to buy a kit which includes a drill bit, tap, install tool, and insert. The link below lists sizes –the link to page 359 has a lot of info.
This company – MSC Industrial Supply – has a great online catalog with a lot of good technical info.





http://www1.mscdirect.com/CGI/N2DRVS...00000002203677

 

Good luck with the repairs.

 

I've used JB WELD on a lot of repairs over the years...it's a great product, but it's not intended for this type of repair or application. Unfortunately, I think it'll ultimately fail and you'll still have the issue (and have to remove the epoxy).
Good advice to use a more permanent repair with replacement thread inserts.

 

Please don't use JB Weld for this repair.............

There is another option to Heli-Coil or Keen-Sert (these are both good products). We sell a product called EZ Lok inserts, however these require a larger hole drilled than either the Heli-Coil or Keen-Sert. I am assuming the valve cover bolt is a 6mm? If so, a 6mm EZ Lok requires that you drill a 5/16" hole, tap 3/8-16 threads, and then screw in the insert. You may not have enough material to drill & tap this large, but the EZ Lok insert is heavier and stronger.

 

somebody else thinks like me

either drill and tap to next larger size if possible
if not, get a heli-coil

 

I work for Jergens Inc (www.jergensinc.com) we manufacture thread repair inserts so I am familiar with all the afore memtioned products. No chemical product will be a permanent solution. You have three real choices. Heli-Coil it has the smallest outside diameter used when there is a chance of break out or in where the wall thickness is not suficent to install a solid body insert. You drill the hole out with their special drill, clean out the chips, use their special tap, install the insert break off the tang used to insert it and your done. You need to buy a complete repair kit containing all three pices. Solid body inserts are availible in thick wall and thin wall. EZ-Lok has an epoxy on the outside that activates from the friction of insertation. The stake style of insert that we and Keen-Sert manufacture are what the Millitary use to strengthen holes in Aluminum. For your application a thin wall should do just fine. You drill using a standard size drill bit (be sure to check what size to use it is not a standard tap drill size). Tap the hole, clean it out, run the insert in, drive the stakes in and your done. If you use a EZ-Lok you must have ALL THE TAPING OIL CLEANED OUT OF THE HOLE. Or the epoxy will activate but not hold anything. If the insert comes out with the bolt when you take the valve cover off you'll need to remove it from the bolt before you can remove the bolt from the valve cover. Then you'll have to use another one. That is why they are not used by the Millitary. Check out these pages

http://www.jergensinc.com/infodir/ca...?GroupNum=1071

http://www.jergensinc.com/infodir/ca...?GroupNum=3017

Good luck with your repair!

 

Well............here is the latest. My C5 sits. The JB Weld did not harden. The Permatex would not harden. The Permacoil seems like it would but the hole is now so big that I think I would have to step down several times to get the fit right. I mean by putting a succession of smaller Permacoils into the one that actually fit the current hole. What a mess! Refilling the hole with weld and then just starting over is out unless I take the head off......I really don't want to, but............... I appreciate all the input and really like the insert idea, but how will it work in a hole that is now 3-4x the original size??? Let me know if you do.......as for now.......my C5 and I sit.

 

If you can clean out the hole. That is, if you can successfully remove all of the JB Weld residue, then I still think you could be successful using the alumiweld product. As I said, before, this product is advertised to be harder than aluminum, and it is applied using a regular portable propane torch, like you'd use to sweat copper water pipe, so the temperature is not nearly as hot as regular welding. I have not personally used this product, but I have seen it used on their info-mercials, it looks to be just the ticket for your problem. They demonstrated using the product to repair an aluminum transmission case that had a missing mounting bolt 'ear', and after making a tin mold for the corner piece, and filling it in with the alum-weld product using just the portable propane torch, a little grinding and then drilling out the new hole, you couldn't tell the repair from new.

 

I agree,
I think the Keen-sert's or the Jergens MRO thread repairing kits are the way to go, I’ve used Keen-serts before and they work great. If you look at the Jergens product a M6x1.0 thread repair insert uses a 10.8mm/0.425” drill for a insert OD thread of M12x1.25. A M6 has a major diameter of 5.94mm/0.234” Is your hole now bigger then 0.425” diameter , is it round or AFU ? Screw all that epoxi crap do it right and forget about it . Post your hole diameter and maybe a picture and I’m sure the board can help.

 

I have used this stuff and it was pretty amazing how well it worked! might be worth a look!http://www.cisoldit4u.com/alumaloy.htm

 

"Harder" than aluminum is very easy to do. On the Mohs hardness scale, Al has a hardness of 2.75, just slightly harder than a fingernail: e.g., talc is 1, gypsum 2, copper penny 3, quartz 7, hardened steel 7-8, diamond 15. Of course Al alloys may be somewhat different.

Tensile strength is an entirely different matter. Torquing a bolt into -whatever- is still more complicated.

I would give up on chemicals for this. And this from a guy who likes chemicals. Good luck.

 

Well...contacted Jergens re inserts but the wall is now too thin to accept it. I managed to obtain an aluminum blank of the correct size, tap the hole (best I could) and then threaded the outer portion of the blank, cut to fit the hole, then drilled a center hole and tapped it to the right size....and guess what? My crude "insert" worked! I have since obtained a new torque wrench in INCH LBS(!) and put it all back together. The cover torqued down to 106 inch lbs on all 4 screws as noted in the factory manual (best $125 I have spent). Then cruising at 45MPH with oil pressure at 50 heard a "phooshh" and found the valve cover gasket half pushed out and oil all over the intake, ex manifold, etc.. This has happened now 3 times. I have removed the gasket, cleaned the gasket surfaces of both the head and the cover, used new gasket (Genuine GM), rechecked and retorqued only to have it happen again, again, again, again..........I ask, who did I **** off? Any suggestions friends..........One thing I will offer to those who come after me......it's INCH LBS on the valve cover.

I guess one day Andy at A and A will talk me into a stroker and this current head will be used as an anchor!