promisberg
2004, t1n, 3/4t, 140-shc
2004 T1N OM-647 motor.
Here is one solution to a broken injector bolt in the head. Dealer said they would pull the head-no thanks, other local merc mechanics had no special tools for this job and had not fixed this issue.
First, Thanks to all the other posters on injector seal - black death subject all was helpful. Had I followed other suggestion more closely perhaps I wouldn't have broken the bolt during removal! (PB blaster soak, remove with engine hot, tap sharply, if stubborn gently go back and forth). I will say that these bolt break very easily as I definitely was being gentle. My repair started with needing to replace the injector seal, others have fully discussed that so will not explain my nuances here. Other than if the injector is out or fuel line open etc. cover them.
To the point:
#1, order Time-Sert sprinter injector hold down bolt kit. (5ea 17mm deep x 6x1 thread inserts, extended drill, tap and insertion tool)
#2, go to Ace hardware or a hobby shop and buy thin wall brass tubing of 5/16" and 9/32" diameter. The smaller one should be a nice bag fit in the bigger one and the hold down bolt should fit loosely inside.
#3, buy PB blaster and find a straw that fits.
#4, Tools: cordless drill (note this was on #1 cylinder so easy access for me, you may need angle drill), compressed air W gun and super fine tip, I used spray can straw that fit in my air gun, Tallish tap handle, paper towels, powerful small LED light I used my petzl head lamp, possibly need a mirror.
#5, part off 6" sections of the brass tubing and cut 4 slots 1/16" deep on one end. This makes micro brass core drills.
#6, With the hold down fork out of the way, I could see that I had to slightly oversize the hole in the valve cover so I could access the full diameter of the counter bore in the head. You may or may not have to do that. The injector can be in place until tapping. Spray some PB baster in / near the counter bore for the bolt. Chuck up the 9/32 tube drill, I used a rod inside it so the chuck wouldn't crush the tube. Start gently drilling down through the tar/carbon going both directions. I was going around a 1/4" at a time then spraying PB and blowing out into the paper towels then fresh PB in the hole. eventually you will hit the bottom of the counter bore.
#7, now add the 5/16 core drill to the outside of the 9/32 and repeat above until the counter bore is totally cleaned out. You may notice at this time that the 5/16 tube bag fits nicely in the counter bore. Discovery of this procedure was not by design but perhaps divinely inspired or just dumb luck. I was actually preparing for a different procedure / drill guide for using 1/8" left-handed aircraft drill.
#8, part off 4.5" of each size tube and slide them together and insert into the counter bore. This makes a very simple and highly effective drill guide that just happens to fit the Time-Sert drill with a loose bag fit. I was initially a bit worried about the fit but if it worked this saved making another tool and possibly having to do the time-sert anyway.
#9, I started drilling / pecking very gently 1/32" at a time inspecting to confirm I was staying in center. Once I was sure I was on center then I was drilling, removing drill and guide, cleaning all chips from tools and the hole every 1/8" to 1/4" then re-oiling drill tip. I noted that when chips were loading down in the hole the inner brass tube would push up slightly so used that as a guide as to when to clean out. OK you know the drill (pun intended) repeat for this 3.5 or 4 hours! One note is that once I started drilling below the counter bore in the head and into the threaded section the drill grabbed the bolt and tightened it into the head further. Gentle is the key because don't want to drive the bolt into the water jacket. Ultimately the bolt fragment bottomed and I finished drilling it out.
#10, DO THE MATH correctly so you don't drill into the water jacket. When you start getting close you can adjust the chuck on the drill shaft so that it hits the top of the drill guide at measured intervals. I went literally 1mm at a time near the bottom and that paid off as I was able to get all the bolt out and see the factory machining in the bottom of the hole.
Final thoughts were that if I made the 1/8" drill guide on the lathe the the bolt would have spun out and threads were likely still good. However ultimately I prefer the insert anyway because it is more durable. Now I know that the Time Sert procedure doesn't take long so will likely do that when I have to change another seal / injector.
Here is one solution to a broken injector bolt in the head. Dealer said they would pull the head-no thanks, other local merc mechanics had no special tools for this job and had not fixed this issue.
First, Thanks to all the other posters on injector seal - black death subject all was helpful. Had I followed other suggestion more closely perhaps I wouldn't have broken the bolt during removal! (PB blaster soak, remove with engine hot, tap sharply, if stubborn gently go back and forth). I will say that these bolt break very easily as I definitely was being gentle. My repair started with needing to replace the injector seal, others have fully discussed that so will not explain my nuances here. Other than if the injector is out or fuel line open etc. cover them.
To the point:
#1, order Time-Sert sprinter injector hold down bolt kit. (5ea 17mm deep x 6x1 thread inserts, extended drill, tap and insertion tool)
#2, go to Ace hardware or a hobby shop and buy thin wall brass tubing of 5/16" and 9/32" diameter. The smaller one should be a nice bag fit in the bigger one and the hold down bolt should fit loosely inside.
#3, buy PB blaster and find a straw that fits.
#4, Tools: cordless drill (note this was on #1 cylinder so easy access for me, you may need angle drill), compressed air W gun and super fine tip, I used spray can straw that fit in my air gun, Tallish tap handle, paper towels, powerful small LED light I used my petzl head lamp, possibly need a mirror.
#5, part off 6" sections of the brass tubing and cut 4 slots 1/16" deep on one end. This makes micro brass core drills.
#6, With the hold down fork out of the way, I could see that I had to slightly oversize the hole in the valve cover so I could access the full diameter of the counter bore in the head. You may or may not have to do that. The injector can be in place until tapping. Spray some PB baster in / near the counter bore for the bolt. Chuck up the 9/32 tube drill, I used a rod inside it so the chuck wouldn't crush the tube. Start gently drilling down through the tar/carbon going both directions. I was going around a 1/4" at a time then spraying PB and blowing out into the paper towels then fresh PB in the hole. eventually you will hit the bottom of the counter bore.
#7, now add the 5/16 core drill to the outside of the 9/32 and repeat above until the counter bore is totally cleaned out. You may notice at this time that the 5/16 tube bag fits nicely in the counter bore. Discovery of this procedure was not by design but perhaps divinely inspired or just dumb luck. I was actually preparing for a different procedure / drill guide for using 1/8" left-handed aircraft drill.
#8, part off 4.5" of each size tube and slide them together and insert into the counter bore. This makes a very simple and highly effective drill guide that just happens to fit the Time-Sert drill with a loose bag fit. I was initially a bit worried about the fit but if it worked this saved making another tool and possibly having to do the time-sert anyway.
#9, I started drilling / pecking very gently 1/32" at a time inspecting to confirm I was staying in center. Once I was sure I was on center then I was drilling, removing drill and guide, cleaning all chips from tools and the hole every 1/8" to 1/4" then re-oiling drill tip. I noted that when chips were loading down in the hole the inner brass tube would push up slightly so used that as a guide as to when to clean out. OK you know the drill (pun intended) repeat for this 3.5 or 4 hours! One note is that once I started drilling below the counter bore in the head and into the threaded section the drill grabbed the bolt and tightened it into the head further. Gentle is the key because don't want to drive the bolt into the water jacket. Ultimately the bolt fragment bottomed and I finished drilling it out.
#10, DO THE MATH correctly so you don't drill into the water jacket. When you start getting close you can adjust the chuck on the drill shaft so that it hits the top of the drill guide at measured intervals. I went literally 1mm at a time near the bottom and that paid off as I was able to get all the bolt out and see the factory machining in the bottom of the hole.
Final thoughts were that if I made the 1/8" drill guide on the lathe the the bolt would have spun out and threads were likely still good. However ultimately I prefer the insert anyway because it is more durable. Now I know that the Time Sert procedure doesn't take long so will likely do that when I have to change another seal / injector.
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