head stud pulling out

[tumblingtwerp9]

So previous owners were idiots but when I built this motor the rear most stud pulled out of the cylinder when being torqued. I helicoiled the hole and it held. It has been ridden about 5 to 10 hours since then. Well this past weekend we went out to ride and at the end of the day I blew the headgasket in the exact spot that the stud is at and the stud is starting to pull out again.

Idk if it is pulling out when it gets hot and has pressure on it or what but I need to fix it.

Any ideas on how to fix the head stud?

 

[mud runner]

kind of sounds likeit is vibrating out but not 100% sure

 

[sicivicdude]

So previous owners were idiots but when I built this motor the rear most stud pulled out of the cylinder when being torqued. I helicoiled the hole and it held. It has been ridden about 5 to 10 hours since then. Well this past weekend we went out to ride and at the end of the day I blew the headgasket in the exact spot that the stud is at and the stud is starting to pull out again.

Idk if it is pulling out when it gets hot and has pressure on it or what but I need to fix it.

Any ideas on how to fix the head stud?

Was the head torqued properly when it was installed and rechecked after heat cycles? MOST head/stud problems come from overtorquing or not retorquing.

Once a hole has been helicoiled, the only method left to "simply" rethread is a Timesert Bigsert. The kit is expensive enough ($75) to warrant having it done elsewhere as long as it's only one hole pulling out. If you have multiple problem holes (and are quite industrious) you can Bigsert yourself, just be VERY careful removing the helicoil.... they're springy steel wire and tries to grab drill bits (and drills, wrists, and power cords). If you're lucky, you'll get the first wind to start up out of the hole and you'll be able to pull the rest of the helicoil out with a pair of pliers or similar removal device.

The timeserts are basically the same idea as a helicoil but are actually a threaded "tube" instead of a wound wire that installs to make new threads. The Bigsert kit is an oversized version of the regular Timesert kit made for holes that have already had an insert installed.

 

[dksix]

I've never had any luck with helicoils, I use something like I think Civic is referring to but just call them thread inserts. I've always made my own but a solid insert takes more room than a helicoil. Its basically a threaded rod with a threaded hole in it, I've used the threaded section of grade 3 bolts to make them. I've even Dutch keyed them so there is no chance of them unthreading but you really need a lathe to make your own.

 

[sicivicdude]

I've never had any luck with helicoils, I use something like I think Civic is referring to but just call them thread inserts. I've always made my own but a solid insert takes more room than a helicoil. Its basically a threaded rod with a threaded hole in it, I've used the threaded section of grade 3 bolts to make them. I've even Dutch keyed them so there is no chance of them unthreading but you really need a lathe to make your own.

That's basically what the Timesert kit is. It does take quite a bit more "meat" in the area to be installed into than a helicoil but the Timesert kit is considered "full torque" thread replacement.

I have had some luck with helicoil's holding in limited torque applications. I've seen them hold securely (installed perfectly) under torqued applications too but I've also seen them pulled out under torqued applications too

The Timesert kits are over drilled, counterbored, tapped, and then inserted using a special insertion tool. They are "locked" internally to the new threads by use of the special insertion tool that expands the outside threads into an interference fit with the newly tapped hole. I've never had one back out using that method but I'm sure with enough wrenching it *could* happen. I like the idea of dutch keying it, in addition to the locking mechanism provided but there isn't a lot of "meat" around a head stud hole already. A Bigsert insert takes up what is available. If one was to dutch key it, it would be off to the side outside of the normal head mating surface. Not sure how that would react to thermal swings .... more thought is required on the subject!

 

[OConnor Racing]

This is a very common problem. We remove the old stud and install a Honda CR 500 replacement. I think the stud is under $5. You'll need to drill the hole and tap for the new step stud.

 

[dksix]

This is a very common problem. We remove the old stud and install a Honda CR 500 replacement. I think the stud is under $5. You'll need to drill the hole and tap for the new step stud.

You say stepped, do you mean bigger below the cylinder surface but the same diameter throught the head and using the same head nut?

 

[sicivicdude]

This is a very common problem. We remove the old stud and install a Honda CR 500 replacement. I think the stud is under $5. You'll need to drill the hole and tap for the new step stud.

My only concern with that method would be if someone has a problem with that stud later like stripping threads or bending it somehow.

The current owner (maybe not even the person you replaced that stud for) would need to know that what stud they would need to source. They can't order one for a blaster from the dealer (or anywhere) and it work right off.

That being said, if it's a step stud with a M8 x 1.25 on the top, sounds like it would get by the problem of having the original M8 x 1.25 hole stripped out just like a "replacement thread" option.

 

[dksix]

That being said, if it's a step stud with a M8 x 1.25 on the top, sounds like it would get by the problem of having the original M8 x 1.25 hole stripped out just like a "replacement thread" option.

He said he already tried a helicoil, they have to be drilled and tapped bigger than the original thread. What if the step stud is smaller than the tapped hole for the helicoil?

 

[tumblingtwerp9]

Ken can you tell me what size the bottom of the cr500 stud is so I can see if it will be too small or not since I already drilled for helicoil?

 

[OConnor Racing]

It's bigger. We use this repair for the LA Sleeve cylinders before we even run them. Works great and thanks to Kenny Gibson for the feedback. Just carve "CR 500 studs have been installed" on the top of the cylinder. No more questions.

 

[dksix]

Ken can you tell me what size the bottom of the cr500 stud is so I can see if it will be too small or not since I already drilled for helicoil?

I looked up the part number for the CR500 head stud (90032-KA5-690) and found a picture of the stud. I checked the tap size for an M8x1.25 helicoil and it uses a M10x1.25 tap. So, if the helicoil pulled out of the hole, you'll need something bigger than a M10 thread. It's hard to tell from a pic but if the small threads are M8, the big threads look like an M10. I texted a friend who has some CR500's to see if he has a cylinder missing a head stud that he could check but haven't heard back from him yet. If I can find out anything else, I'll let you know.

 

[sicivicdude]

I looked up the part number for the CR500 head stud (90032-KA5-690) and found a picture of the stud. I checked the tap size for an M8x1.25 helicoil and it uses a M10x1.25 tap. So, if the helicoil pulled out of the hole, you'll need something bigger than a M10 thread. It's hard to tell from a pic but if the small threads are M8, the big threads look like an M10. I texted a friend who has some CR500's to see if he has a cylinder missing a head stud that he could check but haven't heard back from him yet. If I can find out anything else, I'll let you know.

What I meant earlier was if it's a stepped stud with the top half being M8 which would allow it to be used in the existing blaster head.

I went out and measured my helicoil kit's M8 x 1.25 STI tap (the funky one supplied with the helicoil kit) and it measure not quite 10mm (like some funky sized 9.77mm?!) but the point is exactly the same. If a helicoil has already pulled out, that hole is ruined for a M10 x 1.25 stud of any shape design or origin.

Coincidentally, I went out and measured (and took pics of) the Bigsert kit. It uses a true M12 x 1.5 tap and M12 counterbore tool (I guess when you're not trying to "match" the ID of threads they can use a standard size?) for installation.

Personally, I wouldn't want a thread repair that doesn't use the stock sized stud but that's neither here nor there (again, agree to disagree?).

To the OP, you DO have options left out there no matter what.

 

[sicivicdude]

So it comes in a tiny little box....

Inside, looks a lot like this, 4 "tools" included and (in the standard Bigsert kit, 5 inserts)

The side of the insert has a small indentation area

The insertion tool is tapered to push that area out into the new threads to lock the insert:

One after installation (note all of the splooge residue around the front of the cylinder, however some of that is honing oil)

And coincidentally the back hole helicoiled and holding:

The front hole was actually holding fine, it was just tapped crooked and then coated in loctite so upon removal it took out the threads too. Bigsert became the only option at that point.

 

[tumblingtwerp9]

good to know...I'll try to get the helicoil to hold this time since I have a theory why it only pulled out about 3 threads and then torqued and if it doesn't hold this time I'll bigsert it.

 

[sicivicdude]

good to know...I'll try to get the helicoil to hold this time since I have a theory why it only pulled out about 3 threads and then torqued and if it doesn't hold this time I'll bigsert it.

I cannot stress this enough. YOU HAVE TO BE VERY CAREFUL trying to remove a failed helicoil. Drill bits will "dig" and try to yank the drill and anything attached to it out of your hand. It is best to do this type of work on, at a bare minimum, a drill press with a drill press vise.

The best case scenario would be a milling machine with the cylinder clamped SOLID to the table and some sort of "blast shield" between you and the drill bit.... That spring steel wire that helicoil is made out of is some TOUGH STUFF.

 

[dksix]

Here is one of the ones we make in house for our plates. This plate is being scrapped, so the steel has to be removed from the aluminum before it can go to the recyclers. To give an idea of the holding power, that's an easy out that just broke trying to turn the insert out.

 

[sicivicdude]

Here is one of the ones we make in house for our plates. This plate is being scrapped, so the steel has to be removed from the aluminum before it can go to the recyclers. To give an idea of the holding power, that's an easy out that just broke trying to turn the insert out.

Never tried to extract one of the Bigserts but they seem EXACTLY like what you make from scratch. Timesert advertises their products as "full torque" inserts.

 

[dksix]

Never tried to extract one of the Bigserts but they seem EXACTLY like what you make from scratch. Timesert advertises their products as "full torque" inserts.

I repaired a few Honda transmissions with them, I tested them to 250 ft lb and they held. People are bad to use an impact wrench to pull the engine/tranny up into the mounts, when installing. I've seen several that had the thread pulled out like that. A friend of mine is an MFactory tech, it's more common than what you'd believe for those holes to be stripped out.

 

[OConnor Racing]

Here’s my take on the repair. The stock Blaster stud is screwed into the cylinder until it stops. The only thing holding the stud in is the center of the stud where the threads run out, the top side of the threads in the hole, and stud locker if you used it. When you install a Heli-Coil or any of the above mentioned inserts, you’re just jacking the stud down until it runs out of threads. This is a very small holding surface and may allow the stud to become loose again. If the stud starts floating in its threads, you run the risk of pulling out the threads of the stud or the repair. The CR 500 repair will never fail. The stud is a step stud with a flange at the top of the major diameter. The flange works as a possitive stop and allows the “builder” to torque the stud to a specified tension and seal it against the flange of the stud. This is not an experiment on my end. I’ve performed this repair more times than I care to remember and it works great. If you installed a heli-coil and it failed, don’t even bother to drill a new hole. Pass the tap in for the CR 500 stud and torque it down to 30 ft/ lbs. Make sure you use thread locker on the stud and you’re done for $5. While you’re in there, do all six of them. Like I said, this repair has never failed me. Civic, you seem to know quite a bit about it…………….ever try it?