Help wanted: Mechanical Engineers
Elder User
Joined: Dec 2002
Posts: 797
Likes: 1
From: UT
One thing you could do, one of the links above to Jegs site shows a bolt with a setscrew in the middle that flares the bottom out locking it in place. Then you could have some taper pieces made that the bolt pass through. Heck I could even make you 8 aluminum ones to try out...
Just drew little something up:
Just drew little something up:
Postmaster
Joined: Jun 2010
Posts: 2,555
Likes: 8
From: Longview, TX
I'll just through this out there as an alternative to welding: solder.
You can get solder that melts at 450*, so temp isn't going to cause it to let go. You may have a problem with the bond under the vibration, and it may be too soft to hold, but it's something.
You can get solder that melts at 450*, so temp isn't going to cause it to let go. You may have a problem with the bond under the vibration, and it may be too soft to hold, but it's something.
Posting Guru
Joined: Aug 2010
Posts: 1,002
Likes: 1
I would use safety wire and threadlocker on it. I would have the hole through the bolt head and run the safety wire through the bolt head and around one ear/ side of the hold down on the injector. When you pull it tight and twist the wire it would be clear of the valve springs and rockers. Just have 4 short safety wires rather then one long one. That is my 2 cents anyway. 
This is from a guy that has never been under my valve covers though...
here is my feeble illustration in red..
This is from a guy that has never been under my valve covers though...here is my feeble illustration in red..
Thread Starter
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Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
I would use safety wire and threadlocker on it. I would have the hole through the bolt head and run the safety wire through the bolt head and around one ear/ side of the hold down on the injector. When you pull it tight and twist the wire it would be clear of the valve springs and rockers. Just have 4 short safety wires rather then one long one. That is my 2 cents anyway. This is from a guy that has never been under my valve covers though...
here is my feeble illustration in red..
This is from a guy that has never been under my valve covers though...here is my feeble illustration in red..
Set screw... interesting. Do I use thread locker on the set screw?
Thread Starter
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Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
There are some great ideas here, but I need to reiterate inserts: I had inserts in my hands, and helicoils, and all the tools/supplies to install them... but woodnthings knows his stuff and he gave the threads in the heads a thumbs-up. They are good and need no inserts, but he was unable to get the bolts to stay... however, I did the thread cleaning and threadlock. I'll repeat from post #14:
For thru hole applications, such as a nut and bolt combination, threadlocker is applied just to the bolt, coating 3 or 4 threads, going all the way around the diameter, and then assemble. On the other hand, it's critical to apply the threadlocker to both male and female threads for blind hole applications such as a bolt going into a closed housing. If it's applied just to the male threads and torqued down, air pressure will force most of the product back out as you assemble. This will result in incomplete coverage and partial cure only, leading to premature failures.
I just discovered this the day I posted it. I did not apply threadlock to the threads in the heads. My reasoning at the time was to prevent bolt hydrolock. I can't yet rule out my utter newbness with big iron.
For thru hole applications, such as a nut and bolt combination, threadlocker is applied just to the bolt, coating 3 or 4 threads, going all the way around the diameter, and then assemble. On the other hand, it's critical to apply the threadlocker to both male and female threads for blind hole applications such as a bolt going into a closed housing. If it's applied just to the male threads and torqued down, air pressure will force most of the product back out as you assemble. This will result in incomplete coverage and partial cure only, leading to premature failures.
I just discovered this the day I posted it. I did not apply threadlock to the threads in the heads. My reasoning at the time was to prevent bolt hydrolock. I can't yet rule out my utter newbness with big iron.
Postmaster
Joined: Jun 2010
Posts: 2,555
Likes: 8
From: Longview, TX
Are all if the bottom hold down bolts causing problems, or just one or two? The reason I ask is that thread damage on one or two is slightly conceivable. Thread damage on all 8? Not so much. Which also brings up the fact that if just one or two are causing problems, let treat the one or two and not the rest. No point in replacing all the hold down bolts with special applications when there are what, a million other bolts holding just fine.
Assuming there are just a couple causing problems, can you just have a hole drilled through the head and run a wire or cotter pin through it?
Assuming there are just a couple causing problems, can you just have a hole drilled through the head and run a wire or cotter pin through it?
Laughing Gas
Joined: Jun 2013
Posts: 1,026
Likes: 23
If you've used new bolts and proper torque, as you have. It would seem the problem must lie with the threads in the heads otherwise everyone would be having problems with this? I can't even imagine your frustration at this point.
Senior User
Joined: Feb 2004
Posts: 249
Likes: 1
Threadlocker can also be used on the underside of bolt heads. I see OEM using it here more and more on newer cars.
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Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
More history:
This problem originally surfaced on the first day of my 2000-mile vacation trip (October)... that was cut to 1600 miles due to this "mystery". I had injector issues leading up to the trip (which I thought I solved) and new tunes, so between the tunes, the sticks, and the strange new symptom (bolts loosening without my knowledge), the monkey poop-fest made a spectacular entrance. Bypassing the first 6 VC lifts with the reman injectors, I'll share what I found on bolt swap #1. It started with injectors 6 and 8, but it's in some migratory pattern from hell to tarnation.
New:
What I pulled out:
The contact points on the injector hold-down bracket.
Some of the old upper bolts were bent, so new uppers were installed all around and they have never loosened (you can believe I check 'em). I make sure the hold-down bracket is in the correct position each time in an effort to maximize the contact surface with the lower bolt, but I haven't ruled out this may be a mistake. I pulled all the remans and went with new sticks (Buck$Zooka is getting a real workout). I have since lifted the VCs at least a dozen more times... so I'm sneaking up on about 20 lifts (and I'm getting real good/fast at it). Why so often? I now have an ear for an injector working its way loose: It's a much subtler version of the nightmare from my vacation... like smelling a match after surviving a forest fire. I keep my torque wrench under the back seat (tension off). Pathetic, eh?
Anyway, it started with cylinders 6 and 8... then moved to 7 and 1, then moved to 2 and 8, then just 7, with each lift presenting me with a fresh puzzle. My last lift was 7, 2, and 4... but it will change the next time I get in there. I used to get about 300 miles between lifts, but now I get anywhere between 1000 and 1500 miles. My one saving grace - 5 has been stable (so far). Did I mention I HATE messing with 5? Shoot me a K.I.S.S. solution... or just shoot me in the kisser. Either way, no more VC lifts.
This problem originally surfaced on the first day of my 2000-mile vacation trip (October)... that was cut to 1600 miles due to this "mystery". I had injector issues leading up to the trip (which I thought I solved) and new tunes, so between the tunes, the sticks, and the strange new symptom (bolts loosening without my knowledge), the monkey poop-fest made a spectacular entrance. Bypassing the first 6 VC lifts with the reman injectors, I'll share what I found on bolt swap #1. It started with injectors 6 and 8, but it's in some migratory pattern from hell to tarnation.
New:
What I pulled out:
The contact points on the injector hold-down bracket.
Some of the old upper bolts were bent, so new uppers were installed all around and they have never loosened (you can believe I check 'em). I make sure the hold-down bracket is in the correct position each time in an effort to maximize the contact surface with the lower bolt, but I haven't ruled out this may be a mistake. I pulled all the remans and went with new sticks (Buck$Zooka is getting a real workout). I have since lifted the VCs at least a dozen more times... so I'm sneaking up on about 20 lifts (and I'm getting real good/fast at it). Why so often? I now have an ear for an injector working its way loose: It's a much subtler version of the nightmare from my vacation... like smelling a match after surviving a forest fire. I keep my torque wrench under the back seat (tension off). Pathetic, eh?
Anyway, it started with cylinders 6 and 8... then moved to 7 and 1, then moved to 2 and 8, then just 7, with each lift presenting me with a fresh puzzle. My last lift was 7, 2, and 4... but it will change the next time I get in there. I used to get about 300 miles between lifts, but now I get anywhere between 1000 and 1500 miles. My one saving grace - 5 has been stable (so far). Did I mention I HATE messing with 5? Shoot me a K.I.S.S. solution... or just shoot me in the kisser. Either way, no more VC lifts.
Cargo Master
Joined: Mar 2006
Posts: 2,502
Likes: 2
From: Bend Oregon
could you take a set of bolts to a machine shops had have the tapered faces knurled?
Straight knurling a 45deg chamfer - will this work
reading through the discussion posted on the link above I believe it can be done
This may be an approach you want to try if the PROPER application of threadlocker does not work ( this is an Alex Trebeck comment due to the fact I had no idea you had to add thread locker to a blind hole before you informed me but made the statement as if it was common knowledge).
Straight knurling a 45deg chamfer - will this work
reading through the discussion posted on the link above I believe it can be done
This may be an approach you want to try if the PROPER application of threadlocker does not work ( this is an Alex Trebeck comment due to the fact I had no idea you had to add thread locker to a blind hole before you informed me but made the statement as if it was common knowledge).
Elder User
Joined: Dec 2002
Posts: 797
Likes: 1
From: UT
By the picture of those new and old bolts, it appears the bolt is malleable and has a softer taper than the seat. Are the heads stripping easily also? To me that looks like your problem. The bolt is probably stretching like bubble gum.....lol.
Could you use one of these?
What size thread and length are they?
Could you use one of these?
What size thread and length are they?
Lead Driver
Joined: Jun 2013
Posts: 5,647
Likes: 891
From: north of Minneapolis, MN
Tugly,
Been following this. Think about a drilled stud on the lower with a castle type nut, machined with a proper taper to match the factory bolt, then insert a cotter pin. Or as the above reply, a tapered seat under a standard castle nut.
Dan
Been following this. Think about a drilled stud on the lower with a castle type nut, machined with a proper taper to match the factory bolt, then insert a cotter pin. Or as the above reply, a tapered seat under a standard castle nut.
Dan
Senior User
Joined: Feb 2004
Posts: 249
Likes: 1
Ok, heres a shot from outer space, but is there any chance theres a borderline hydraulic effect during combustion and its forcing the injector to bounce or stretch bolts, mash threads, etc...? Maybe from too much fuel during combustion, or too early of an injection/combustion event, hpop pressures/timing? Really reaching/guessing/trying to spark ideas. Hope I dont sound stupid
Posting Guru
Joined: Aug 2009
Posts: 1,025
Likes: 0
From: ellensburg
I think you need to find the cause before you try any crazy fixes. How many people have swapped injectors, pulled injectors, or serviced injectors without this issue?
You obviously have something CAUSING this problem, and if you do not find out the cause and address it, no matter what you do that issue will still be there and even if you secure the bolts, then it will find the next weakest link. Imagine you secure the bolt, but the same force is still trying to push the injector out. Whats the next weak link....cups? Injector? Valves? Piston? Rings? Head? No matter how much of a PITA it is, I'd say any of those options is much worse than bolts coming loose...
Address the root cause, not the symptoms.
You obviously have something CAUSING this problem, and if you do not find out the cause and address it, no matter what you do that issue will still be there and even if you secure the bolts, then it will find the next weakest link. Imagine you secure the bolt, but the same force is still trying to push the injector out. Whats the next weak link....cups? Injector? Valves? Piston? Rings? Head? No matter how much of a PITA it is, I'd say any of those options is much worse than bolts coming loose...
Address the root cause, not the symptoms.
Post Fiend
Joined: Sep 2003
Posts: 6,096
Likes: 26
From: Mesa AZ
Almost every mechanic that I know who works on HEUI engines use Loctite and hand turns the bolts about 1/8-1/4 turn past the torque value specified. They say they were having too many come backs when using just the book method.