Injector bolt help!!!'

Shortbus906

New member
Ok folks,
Here it is...worst case scenario. Bought a 118 with 197k from CT, not so bad so far, brakes, shocks, belt and alternator stuff, RSN...all normal stuff. I've been a German car Tech for almost 30 years, so no big deal.

Yesterday, little ticking from the engine...then pop!! Open the hood and find #4 injector popped and the hold-down bolt broken. Argh!!! I was really beginning to love my little rig.

So now...options everyone??? I'm reading horror story after story, anybody actually fix this in the vehicle or should I just pull the front end and head, do timing chains, injectors and a valve job?

Has anyone used the Timecert extended length kit? How do I reach Doktor A? To see about the special tooling he's mentioned a few times for doing this repair?

Now...I'm a better than average Technician...and pretty regularly pull a rabbit out of my posterior, and the possibilities of this going wrong scare me to death....really!!! So any suggestions would be appreciated...

Matt
 

surlyoldbill

Well-known member
A broken bolt can be extracted or drilled out. Worst case scenario is pulling the head of and doing it on the bench; which is just time consuming as far as I know. I drilled mine out and installed a helicoil tens of thousands of miles ago. I know I know, timesert is better, but I had limited time and resources!
 

lindenengineering

Well-known member
Matt
As a tech forget the timesert dealy, its far too tedious to install in situ!
Cut out as much of the broken tail as you can but don't go down too far ''cos you will puncture the jacket.:thumbdown:

Now thread the hold down bolt hole & sleeve section 7/16th UNC using a cutting then bottoming tap. Shop air clean out the hole.
Now choices; get some threaded bar stock in carbon or M/S and bore out the middle and thread to 10x1 mm.

Cut a screwdriver slot in the end, taper recess for ease of entry of the new hold down bolt and then part off the bar at 1 inch 25mm.
Screw in the insert to bottom and fit your injector and new bolt.

These days I have gone one further using stainless and a female hex socket recess which I get made up in India.
But the Home Depot bar stock works for one off.

You will be back on the road in no time and done it many times.
Dennis
 

Dougflas

DAD OWNER
Matt
As a tech forget the timesert dealy, its far too tedious to install in situ!
Cut out as much of the broken tail as you can but don't go down too far ''cos you will puncture the jacket.:thumbdown:

Now thread the hold down bolt hole & sleeve section 7/16th UNC using a cutting then bottoming tap. Shop air clean out the hole.
Now choices; get some threaded bar stock in carbon or M/S and bore out the middle and thread to 10x1 mm.

Cut a screwdriver slot in the end, taper recess for ease of entry of the new hold down bolt and then part off the bar at 1 inch 25mm.
Screw in the insert to bottom and fit your injector and new bolt.

These days I have gone one further using stainless and a female hex socket recess which I get made up in India.
But the Home Depot bar stock works for one off.

You will be back on the road in no time and done it many times.
Dennis
Can you post a picture?
 

220629

Well-known member
Can you post a picture?
Sometimes it is called a bushing. eg. - 3/4 x 1/2" pipe reducing bushing.

What Dennis describes will basically look like a repair bushing except the exterior thread will be 7/16 UNC (coarse = http://en.wikipedia.org/wiki/Unified_Thread_Standard ) with the tapped inside hole being 10 M6 x 1 mm metric thread for the hold down claw bolt.

It is basically this, but larger.

Bushing.gif

http://www.mscdirect.com/product/de...gle-PLA+-+Test&CS_003=7867724&CS_010=96298591

After a short search I didn't find any commercial combined standard SAE (English) exterior thread with metric inside thread repair bushings.

:2cents: vic
 
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Midwestdrifter

Engineer In Residence
After a short search I didn't find any commercial combined standard SAE (English) exterior thread with metric inside thread repair bushings.

:2cents: vic
There are a large variety of inserts available to repair similar damage. This includes inserts that have inch external and metric internal threads.

Mcmaster Carr has a good selection.
http://www.mcmaster.com/#standard-threaded-inserts/=xhb0no

I did a quick look through, but M10 with a 1mm pitch is an uncommon thread for inserts it seems.

Correction the correct thread is M6-1.0mm, and there are a number of inserts with this profile.

here are a couple
http://www.mcmaster.com/#90259a222/=xhbg05

http://www.mcmaster.com/#90245a171/=xhbgfg


Unless there are very thin walls in the head, there is no reason that an insert with M11 or M12 external threads could not be used. 7/16 inch is 11.1mm.
 
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lindenengineering

Well-known member
There are a large variety of inserts available to repair similar damage. This includes inserts that have inch external and metric internal threads.

Mcmaster Carr has a good selection.
http://www.mcmaster.com/#standard-threaded-inserts/=xhb0no

I did a quick look through, but M10 with a 1mm pitch is an uncommon thread for inserts it seems.

Correction the correct thread is M6-1.0mm, and there are a number of inserts with this profile.

here are a couple
http://www.mcmaster.com/#90259a222/=xhbg05


http://www.mcmaster.com/#90245a171/=xhbgfg


Unless there are very thin walls in the head, there is no reason that an insert with M11 or M12 external threads could not be used. 7/16 inch is 11.1mm.
Yes erratum
Interior thread should be 6x1mm
My bad
Dennis
PS the hole is a perfect diameter to accept 7/16th UNC
Trying something else you do at your peril.
My method is tried and tested.
Dennis
 

220629

Well-known member
I didn't stumble on to the McMaster-Carr parts in my search. I probably should have just gone there right away.

I hate to bring back the myth, but in this case length matters. Some of the repair bushings offered are quite short. I too think that the 7/16 UNC coarse thread is good for applying to the aluminum head as opposed to some other fine(r) thread.

Some discussion is here.
I like the 7/16" UNC idea. My experience with fasteners in aluminum masts and other aluminum parts has me believe that a coarser thread in aluminum is better than a finer one. Eg. - 10-24 holds better than 10-32 even though there are less threads per inch.

Why not just use a 7/16 UNC ss steel bolt or all thread to drill and tap to 6x1 mm? Chuck the stock in a lathe and drill/tap. Then cut your screwdriver slot. I don't see where being more concentric than that is critical. :idunno:

http://www.grainger.com/product/GRAINGER-APPROVED-18-8-Stainless-Steel-Threaded-WP168688/_/N-8k5Z1z0o3o3?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/29DH90_AS01?$smthumb$

Back to the Freightliner job.

As has been said, dis-assembly gives more assured results, but there is risk in needing to remove all the injectors. Second guessing what the business wants to do will probably not be well received or help your situation. In my opinion, if you don't agree with the repair method your only real option would be to take the vehicle to somebody else who is comfortable doing the repair differently.

vic
Good information. :thumbup:

I've thought a bit about if the water jacket is pierced. I believe there is a rescue available for that.

My thinking is that an inside/outside threaded insert as Dennis has described could be installed as he outlines.

The difference for a breached cooling passage would be that the insert would have a closed end so the JB Weld doesn't squeeze up into the threads. Added: The thin closed end could be accomplished by using a thin coat of JB Weld on the barrel end, or by using a disc of shim stock glued into place with JB Weld. In either case that JB Weld end seal would need to cure before installation.

Back to installation.
Before installation a bit of JB Weld would first be applied at the bottom of the hole. (Not too much because you might fill the cooling passage. How much you might ask? :idunno:) The JB Weld would be squeezed down into the damaged area as the insert was screwed into place. As long as the metal at the bottom was properly cleaned I'd almost guarantee sealing and long term success.

The new stretch bolt could be shortened a bit to accommodate the closed end insert reducing the overall threaded depth. Losing a couple threads is not critical when threading into the steel insert. It is much stronger than the original aluminum. (Shortening the bolt wouldn't be needed with a shim stock end cover.)

Be certain to dry fit everything before adding the JB Weld to the bottom of the hole. Once the JB Weld cures with the insert in place there is likely no going back.

Mostly thinking out loud. vic

As always, the original post/thread can be accessed by clicking the blue arrow icon within any quote box.

I also think that it is important to match the OEM thread length to approximate the required torque for the hold down claw installation. (That of course ignores the fact that the claw bolt threads will no longer be in aluminum, but in some other metal.)

vic
 
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Dougflas

DAD OWNER
I think that for the most part, any time you cut a thread in aluminum, you should use a coarse thread because they are stronger.
 

Costin

New member
I have a E220CDI 1999, guess that has the same principe regarding the injector hold down, a long M6 screw. I managed to break a bolt on my when I was about to replace a injector seal. There is a MB genuine tool set for drilling out the screw, I borrowed it in my local MB workshop and followed the instructions. Mainly they say "insert guide, drill 1 mm, remove guide, clean hole from debris, insert guide again, drill 1 mm" and so on. The point is to keep the hole as clean as possible so the drill will go straight. It took 2 hours to drill the screw out, then I cleaned the hole with a tap and fitted a new seal and a new screw. The screw is NEVER to be reused, they are cheap to buy so always fit a new one.
All tools used were MB specials, drillguide, drill and tap. Very long drill and tap.
I did not have to use a helicoil, it is still the original threads.
 

PocketDrop

Active member
Any videos on this procedure? I just stripped injector number 3s bolt. I’ve never thread tapped anything, and am having a hard time understanding everything in this thread. Panicking, idk if I can fix this…
 

Fletch9871

Active member
PD...We're going to need more info to know how to help.

Were you installing or uninstalling when the bolt stripped...???
Which year/model of van are working on...???
Please provide detail about what you were trying to accomplish when the oops occurred.

Keep Rolling...Chris
 

PocketDrop

Active member
PD...We're going to need more info to know how to help.

Were you installing or uninstalling when the bolt stripped...???
Which year/model of van are working on...???
Please provide detail about what you were trying to accomplish when the oops occurred.

Keep Rolling...Chris
2006 T1N 2500
I stripped the hold down bolt for injector three while removing. I was hoping to replace injector 3s seal without having to remove other injectors, using the slide hammer and claw. The entire bolt came out, so I don’t have any tail in the hole. It matches the exact length of other used and new bolts. The hole is missing basically half its threads, based on what came out with the bolt.

From what I can tell, I’ll need to

Remove all injectors and the HP fuel line
Remove gasket cover
Tape and cover everything to not spread debris
Re-tap the hole (I shouldn’t have to drill because the full bolt came out?)
Install sleeve
clean the hell out of everything and remove shavings.
install over and all other injectors with new hold down bolts and seals.

Im primarily confused about tapping the hole, and then installing the sleeve.
what tool do I need for tapping? What does the entire tapping process entail?
What are the different options for the sleeve? Why are there different options in general? What do I have to search in order to find this part? How do I install said sleeve? From what I understand, I just screw it in. Are there torque requirements for the sleeve?
When all is said and done, the sleeve should be how long? Am I now only screwing the bolt ONLY into the sleeve? Do the torque specifications stay the same for the hold down bolt? And lastly, suggestions on how to heat the engine (now that I can’t safely run it because of bolt #3) and loosen the injectors?

Thanks so much for responding. I was basically mid panic-writing a new thread referencing this one
 
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PocketDrop

Active member
Okay, so I’ve done a lot more looking at parts and I’m feeling a bit more confident in this.

On the parts that I stated a bunch of questions for, here are answers that I think I’ve puzzled out.

I’ll be using a 7/16-32 to tap the hole. Based on videos, I’ll be hand cranking to tap, going nice and slow. After I tap, I’ll shop-vac the hell out of everything, using various Jerry rigged straws and such to get into everything.
Then, I’ll acquire a 7/16-32 UNC threaded rod, and cut it down to 1” (25.4mm). I’ll a drill a hole in said rod, and then thread the inner hole for 6x1mm. After doing so, I’ll saw a notch for a flathead screwdriver on the end. This should all be doable on a table clamp I imagine.
From there, screw the makeshift sleeve into the freshly tapped hole. My hold-down bolt and hold down claw should install normally from there, matching stock torque specs.

My remaining questions are: What sleeve do I use/is the sleeve only necessary for drilling out a broken bolt? Do I drill all the way through the rod, so that my hold down bolt meets aluminum, or do I turn the rod into an end piece, leaving the end intact so the hold down bolt meets either carbon or M/S? What’s preferable, carbon or M/S? The Question of heating still stands as well. #3 is pretty damn stuck. I still have a few threads in it, I think, but it feels sketchy as hell to try to pressure the injectors by driving with that going on..

Silver Linings: all of my injectors get new seals and hold down bolts.
 
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Midwestdrifter

Engineer In Residence
I would opt for an extra long helicoil or timecert before I would try going all the way up to 7/16. If something goes wrong when you go up to 7/16 you have no more additional room to oversize at which point the head is scrap.

As long as you have at least five threads that are functional in the hole there's a good chance that it may still be able to survive a torque down. My personal approach is to first get an extra long bottoming tap and run it down the whole to see if the threads are recoverable.
 

PocketDrop

Active member
As long as you have at least five threads that are functional in the hole there's a good chance that it may still be able to survive a torque down. My personal approach is to first get an extra long bottoming tap and run it down the whole to see if the threads are recoverable.
Just to confirm, that means I would start with a 6x1mm tap?
 

Midwestdrifter

Engineer In Residence
Just to confirm, that means I would start with a 6x1mm tap?
Start with the original thread size. Start it by hand to make sure you get it engaged with the threads properly. And then run it down using a driver tool until you hit the bottom. When you hit the bottom don't keep going because that will destroy the threads. If you don't have experience using a tap watch a few videos to get a feel for it.

The hole is fairly deep, so you may need an extra long tap. You also need to make sure that the hole is completely clean at the bottom, if there is any debris at the bottom the bolt will bottom out and cause the threads to fail.

If the original thread size does not hold, you have the option of going to a thread repair insert. There was a post here where someone used the 7mm injector hold down bolt from a different model of Mercedes with success. However I haven't done the measurements to see if the fitment is good with just increasing the size of the threads in the head.
 

Midwestdrifter

Engineer In Residence
Do you have a photo of the bolt with the pulled threads? That will help inform us about the damage to the hole in the head. Damage to the upper threads versus the lower threads is a different matter.
 

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