Thread size for injector hold down bolt alh

I stripped one thread on one of the injectors hold down for my ALH Jetta, I'm trying to fix it maybe I can use time cert but I do not know the size, I've been also watching videos of HTS 2000, which looks really strong too, but I think with time certs I should be able to fix it. What do you think?

Not something I'd trust glue to hold unless I was only driving very short distances so I could make it home when it failed.

It is an M8 X1.25

HTS 2000 How would you fix a hole with that? Fill it and redrill? Hmmmm....I don't see it.
You'd be real sorry if that stuff gave way.


I would say Timesert or Helicoil. They may even make a tap that follows the old thread and taps the new insert size thread behind it.
I have one like that for glow plugs. Franko6 would know.

Thx you for the thread size, about HTS2000 watching a video, they left the bolt in the hole then they filled it with HTS2000 after it got cold and dried then they use a wrench and retracted the bolt all the way out so it could make the thread, but it is too risky to do that on the ALH head, I'm guessing.

I already had a helicoil and it popped out, so I have 2 choices left either try with timesert, or go with a bigger bolt.

Personally unless you can get a perfect fill with it, I would drill it out, and use a set of helicoils. Filling it and retapping could end in disaster I'f you dont get a solid fill in it. I personally have used plenty of hts2000, muggy weld, and alumaloy. They work great and hold just find, but filling holes this small is really hard to do, even with added flux to get it to flow. You have to tinn the metal with a brush too. Make sure its flawlessly clean if you do.
Also you would have to remove the head to get it hot enough, 800 f for muggy weld and so on, that will melt the oil seals and then you would need a flat fixture to clamp it to and torque it down as to not warp the head. That is a lot of aluminum to heat up

So, just drill and tap it and use a helicoil, unless you want a timesert and are able to red locktight it in place with 272 red. Good for up ton450f

I'll go that route timesert with red 272 locktite

How long for 272 redlocktite to cure and dry anyone knows? So i can torque down with confidence

Just as a general rule (if you don't want to look it up) 24 hours. But you should not need any help with a properly installed Timesert, those things will be stronger than the original thread.

I still have to put redtite in there my helicoil pulled out of the hole when i was torquing it, so it is a must, is there a difference between 271 and 272 redlocktite?, in my area i could easily get 271 but i can't get 272

The real only difference in all the red locktites is temp and thread gap fill for small or larger bolts. All of them will work for you. 272 is good for 450f vs all the others at 300. The reality is that the head will never get past 250 if you have an over heating situation. Thus any of them will work as the others are for use to work with larger than 3/4 diameter bolts.
I am using the 272 due to its higher heat for my exhaust studs on my cb650sc nighthawk but its overkill.
Let it sit for 12 hours before you torque it down.
Heck, blue would work too. Not a high vibration thing unlike my 1000 rpm revving strait 4 motorcycle.
Dont use threadlocker for helicoils, that will pull them back out when you remove the bolt in the future.
Timeserts are probably going to best here like you probably already know by now.

A pro tip, after putting the bolt in 75% of the way put a tilt dab or rtv gasket maker and send it home. This will seal it from corroding out. Antiseiz is garbage and here it will make it worse as it will get too hot and harden up. Its usually best to send bolts in dry but if like on brake bleeder screws or water pump bolts that have a through thread, a dab of gasket maker will make life much easier down the road.

MAXRPM said:

I still have to put redtite in there my helicoil pulled out of the hole when i was torquing it, so it is a must, is there a difference between 271 and 272 redlocktite?, in my area i could easily get 271 but i can't get 272

Click to expand...

Helicoil pulled out of the hole when you were torquing it? Torquing what, the stud?

If it pulled out it must have taken the threads with it so no amount or type of thread locker is going to fix it.

Was the hole you drilled for the Helicoil tap the right size? Usually the drill size is on the tap.

For any insert to hold properly you have to drill the right size hole for the repair tap. Something doesn't sound right here.

no amount of locktite is going to hold a stripped out threads togeather.
the ONLY solution here is to drill the hole out VERY carefully at the correct angle and depth, and tap new threads in it, if any part of the threads are not tapped due to a wallerd out hole, there is no way to fix this with out a jig, if the hole is not exactly center, well dam near close enough, it will not hold properly and will break the hold down for the injector. here watch this video, or skip around. as you can see, if its not center, your screwed.
can you please post some pictures




fortunatly there IS enough meat there that if you didnt go crazy with the drilling, you CAN drill the hole out, then to fill it with a cold compound epoxy mix, then set up a jig to drill a new hole

So i have done this, not on a TDI, but on a few motorcycles
here is the set up
you need like 5 sticks of JB weld epoxy aluminum base epoxy stick, its incredible how well this works, NO JOKE
the right drill bits, just get a set of dewalt bits, your going to need them, a drill and a tap
dont go nuts, there is a water jacket close by
Now put a drill bit that fits back end first into one of the other bolt holes on a good injector hold down mark where it sticks out, wrap the reaming fluts with tape so its smooth and round, not bulky, Now spray lots of wd40 or motor oil or pam cooking spray over the head at this area, now with the drill bit still secured in the hole drill bit facing to you, pack a mountain of putty around it and on to the head, you now have a perfect mold that is the shape of the head around the bit and a guide to align the new drill for the bolt. now with that drill bit, make sure that the hole in your jig is smooth. Clean up the mold release (pam whatever) and now Fill in your jacked up hole with the same putty stuff. a pro tip on this jbweld. roll it into a worm with your hands then back into a ball over and over for a few seconds, it should feel HOT, you have not even a minute to pack it into the hole and tamp it down with a drill bit and keep doing this bit by bit as fast as you can. file it flush, now put your ghetto jig back over the one you made it on, and put the drill bit back face forward this time into the hole and mark how deep it goes, transfer this mark to the proper drill bit for the new hole and using that drill bit, drill out the hole on your jig with progressively larger bits.
after 12 hours, go put the jig on the head, drill down with the correct bit to the proper depth, tap the threads very slowly, and your done. I have been able to torque things down to 40ftlbs with a m12x1.25 and it holds up to heat, your head wont ever see more than 220 MAX if you have mods, JB weld is good for well over that. that bolt gets what mid 20's?

you dont want the big hole you drill to be perfect, if your existing hole has some threads left, use it instead, more bite for the jb weld.

i know im going to get royally pwn3d here for suggesting this and i realize that its probably the dumbest thing suggested here to fix something but, you dont have much to loose at this point, if your stripping our helicoils, the alternative is sending the head to frank06 to be repaired.
its not the right way to do it but dangit, it works, im sorry to say that if done properly this stuff is NUTZ, weld stick and mighty steel stick are also just as good

Ill try with timesert 1st then ill keep your advice as a 2nd option

Just answere us this. Did the helicoil pull out? Did you drill and tap the hole properly?
I am dying to see this please post some pictures

Hellicoil pulled out it got unscrewed as i was untighting bolt so i may have a chance hopefully to fix it with timesert and redlocktite,

If it unscrewed the hole was oversize. Still might hold.

Hope the drill for the new insert is bigger than the OD of the helicoil tap.

I was able to insert timesert and 272 red locktite left there for 20 hrs i was able to torque all bolts at 17lbs, and its holding up great so far

Good to hear. Motor on!

Man ive driven my daly driver for 2 days held up good, did a hard pull and timesert pulled out, losing compression made it home safe so now back to the drawing board, hole is too big for timesert im thinking of going up 1 size bigger from m8 x 125, tap the hole and hopefully i can torque it down. Does Anybody know what next size would be from m8 x 1.25?

You need to stop and contact frank06. I dont know where the water jackets are in the head. Frank06 is king when it comes to this stuff. If the water jacket is close, it could spell disaster
I do know that if the angle isn't correct Its going to put much more stress on the arm.
Please refer to my previous posts about the threads being proper.
Point is bro, unless it's done properly now, it's going to fail.

Can't tell how bad your repair is, but a good epoxy will hold that thread insert much better than any locktite. Your next size would be the drill for the insert, good idea to check if there's enough material to safely drill.
http://www.timesert.com/html/mtrcsert.html

If your going to try epoxy, refer to my previous post on how you need to prep, you cant just fill and drill

Expoxy im sure it will work but a lot work involved, i got me a 3/8 × 16 bolt and tapped it within 25 min i was done, adjusted IQ hammer mod then went for an italian tune up and everything is solid, altough i did talk to frank and he said water jacket are at the bottom of the bolt not to go any deeper than that, he said You can expand the hole by putting a bigger bolt and should not be problem, can't call victory yet until fat lady sing though,