Stripped Head Bolt....

[e_clouser]

So I finally got my block and heads. During assembly I was doing the first stage torque on my head and all went well. During the second stage, two bolts would not take the torque. They just get loose like the threads are stripped. So now my question:
1) Would a Heli-coil be strong enough for the head?

It is bad enough I need to buy a new head gasket now....

Any input?

 

[jimtash]

Use EZ-LOKs or something similar. Very easy to install.

 

[kevinspann]

How loose is loose? If it's not applying any torque, I'd pull the bolt back out to see if that is the issue first.

 

[AREA 91]

So I finally got my block and heads. During assembly I was doing the first stage torque on my head and all went well. During the second stage, two bolts would not take the torque. They just get loose like the threads are stripped. So now my question:
1) Would a Heli-coil be strong enough for the head?

It is bad enough I need to buy a new head gasket now....

Any input?

I am thinking that your torque wrench is a piece of crap!!!
A heli coil is not strong enough for a head bolt application.
They do make specific "inserts" for this.
Take the bolts out and look at them. Are the threads stretched?
Are they new or used bolts? Did you remember the washers?

 

[e_clouser]

I am thinking that your torque wrench is a piece of crap!!!
A heli coil is not strong enough for a head bolt application.
They do make specific "inserts" for this.
Take the bolts out and look at them. Are the threads stretched?
Are they new or used bolts? Did you remember the washers?

They are new bolts, Torque wrench was just calibrated. What are the right inserts?

 

[sperold]

I would not buy a new head gasket just yet. The one you have will work just fine.
Is there such a thing as studs for the head, instead of bolts.
Pull out the head bolts and look to see if they are Chineese pretend grade 8, or whatever.
If there are no studs available, go back to the original bolts. At least you know where they were made.
My bet is, your problem lies in the bolts, not the block.

 

[rubydist]

^ I was thinking the same thing. I have never heard of a head bolt stripping - they are designed to yield before that.

 

[e_clouser]

It is confirmed, it IS the block... I know it is not normal, but that is what happened. Head bolts are fine... There are no distortions on the bolt threads, when you thread the bolt in it wobbles in these two holes and not the others.

 

[jimtash]

Install the thick walled EZ-LOK and be done with it. Drill it out to the size of the insert, tap it, and install. It's easy considering the hole for the head bolts isn't that deep.

 

[sperold]

The only thing I can think of is the head bolt was too long. Before it started clamping the head to the block, the bolt bottomed out in the hole, and all the torque went into galling the threads.
If the head bolts are the right length, then something fell in the threaded hole in the block or you left out some kind of washer or spacer.
Is there a chance there are long and short bolts in this head bolting system?
Use whatever you can to get everything out of the hole and take a bottoming tap and freshen up the threads right to the bottom.
Consider a stud for these bad holes, look for an insert if that is possible. Sounds desperate, but look into plating your stud, either chrome or something like hot dipped galvanizing to give you a few more thousands on your thread form to take the wobble out and mate with your new, non standard thread form, if the insert method is not possible. But you only have one shot at that, you can't keep removing and reinstalling a bolt in these wounded threads.

 

[mgreen1872]

X2 on the Lok

I always spray some carb cleaner into the bolt holes, run a clean tap in to clean threads and finally a round small wire brush... stripped/galled head bolt holes are a pain!

 

[boat]

In the head - block system the head bolts are ALL the same length, it was that way when I did my 3.0 head swap nearly 2 years ago. I purchased a set of head bolts from RCM, and all were of equal length, 4" I believe.

If the bolt was too long, it would not have made it through the first round of torque specs.

I can attest to the fact that Eric's head bolts are all new from SHOSource. And the correct washers were used. I saw this with my eyes.

The head bolts are not too long. He ran the M11-1.5 tap BEFORE ANY bolt went in to make sure the threads were good, no other issues were found on the other 14 bolt holes. The M11 -1.5 tap with the 2 holes in question, the tap was loose, and not tight like the other 14 holes. He placed an M12-1.5 in the 2 holes in question, it was loose as well.

Hey Eric, do the bolts torque back down at the first stage of torque?

 

[e_clouser]

As Boat said, I ran the M11-1.5 tap in every hole, used air to blow out the holes. Bolts are new from SHO Source, Felpro, 4 inch long, and yes I used the washers. The two holes in question the M11 tap would wobble. I knew at that point I was going to have some problems. Now this is were I was just trying anything, I got the M12-1.5 Tap and tried it in the two holes, worked like it should, no wobble(sorry Boat you were wrong on this) I did find the "right" inserts for head bolts but the kits for these cost like 400 dollars. Not worth it in my eyes. I am headed to the hardware store looking for a needle in a haystack, an M12-1.5 x 100mm bolt. As you can guess these are not common. Most that I have found have 19mm hex heads... to big for where it is going. If I can't get this fixed at a reasonable cost then another SHO will hit the scrap yard.
Not anymore Boat.... The first time was the last time. Now the act like they are totally stripped, will snug up, then with just your hands you can get them to "break free".

 

[itwonder]

You should not run a tap into threaded holes in an effort to clean the threads. There are thread chasers for that purpose. A tap is the wrong tool, and can cause more harm than good.

 

[Eric VerValin]

Whats wrong with studs and nuts on top? Have yet to see it on a SHO motor, but see it all the time on others... ?

 

[e_clouser]

You should not run a tap into threaded holes in an effort to clean the threads. There are thread chasers for that purpose. A tap is the wrong tool, and can cause more harm than good.

I have always used a bottom tap when rebuilding an engine. I have rebuilt many of engines and NEVER had a problem. These holes were already messed up. I posted this thread with the purpose of finding a solution to the problem, not to be flamed on my procedures......

 

[e_clouser]

Whats wrong with studs and nuts on top? Have yet to see it on a SHO motor, but see it all the time on others... ?

I see no problem in it except having to pull the engine to remove the back head then... They do sell the m11 - 1.5 stud, but the problem still stands that my block has stripped threads.

 

[itwonder]

I posted this thread with the purpose of finding a solution to the problem, not to be flamed on my procedures......

Yours is the first instance of this issue I have read of in many years on SHOforum, so it might be worthy of consideration that your procedures could benefit from some tweaking. The advice was offered with sincerity (besides being factually correct), and there was no intention of flaming you in any way.

 

[mgreen1872]

I have seen "thread chasers" also but given that they are basically a bolt with slots cut in them and don't really have a cutting edge, I am afraid to use them. If a thread is already damaged or slightly distorted I want something with a cutting edge to "shapen and align" the damaged threads. Rebuilt a lot of motors and just trust the tried and true method better.... but to each their own, ROCK ON!. ... flaming? who's flaming? did I miss something?(seriously)?

 

[boat]

What about a M12-1.5 stud? Do they make those in the correct length you need? You said that the M12-1.5 fit with no wobble. Why not do this?

I see no problem in it except having to pull the engine to remove the back head then... They do sell the m11 - 1.5 stud, but the problem still stands that my block has stripped threads.