On a 2003 325i, I broke the 5mm hex head bolt that holds the camshaft position sensor (exhaust side, passenger side, close to the fan). Any idea how to take that bolt out? I used loctite to threadlock it, so it'll be extra hard. I took the fan out, but the radiator is in the way and I can't get my drill in there.
![Image]()
dropafrank
broken bolt, exhaust camshaft position sensor
On a 2003 325i, I broke the 5mm hex head bolt that holds the camshaft position sensor (exhaust side, passenger side, close to the fan). Any idea how to take that bolt out? I used loctite to threadlock it, so it'll be extra hard. I took the fan out, but the radiator is in the way and I can't get my drill in there.
![Image]()
What is that red stuff? If its loctite, put some heat on it (mini butane jet lighter) to break the bond.
Center punch it, and use a right angle drill with a small left handed drill bit (stay far away from threads). The idea is the left hand bit will catch and hopefully spin out the remnant without needing to drill all the through or outward near the threads.
If you have a welder, then weld a nut onto the remnant and use a socket to turn it out. The heat from welding would help break any rust/loctite bonds.
Center punch it, and use a right angle drill with a small left handed drill bit (stay far away from threads). The idea is the left hand bit will catch and hopefully spin out the remnant without needing to drill all the through or outward near the threads.
If you have a welder, then weld a nut onto the remnant and use a socket to turn it out. The heat from welding would help break any rust/loctite bonds.
First, sorry to hear of your bad luck experience. A broken bolt in a hard to reach area is something we all dread.
As @LeverThis posted, the only way you're getting rid of that red loctite is with heat. Afterwards, you could try hitting it with some penetrating oil to see if that helps. Welding can be a good choice if you have or can borrow the equipment. As far as using epoxy, it rather depends on the type of epoxy. JB Weld might give you a strong enough bond to get some movement on the bolt but of course there's an inherent risk of the jb weld getting into places you don't want it to and making things worse.
Unfortunately, the "easiest" way in situations like this usually involves doing the work you're trying to avoid in the first place such as removing the radiator and any other impediments so you have more room to work on it. Hopefully you're able to get it out without too much hassle. Good luck
As @LeverThis posted, the only way you're getting rid of that red loctite is with heat. Afterwards, you could try hitting it with some penetrating oil to see if that helps. Welding can be a good choice if you have or can borrow the equipment. As far as using epoxy, it rather depends on the type of epoxy. JB Weld might give you a strong enough bond to get some movement on the bolt but of course there's an inherent risk of the jb weld getting into places you don't want it to and making things worse.
Unfortunately, the "easiest" way in situations like this usually involves doing the work you're trying to avoid in the first place such as removing the radiator and any other impediments so you have more room to work on it. Hopefully you're able to get it out without too much hassle. Good luck
A right angle drill attachment should let you drill into the bolt. If the Dewalt one below is too bulky to fit, shop around because there are smaller ones.
Cannot emphasize enough how helpful left hand drill bits will be here as they turn in the direction that loosens the bolt, and everytime the bit catches it will act like an impact working to loosen. Regular drill bits will act to tighten the bolt and work against you. I linked to a stubby (mechanics) left hand drill bit set below that should work.
Just saw that red loctite was in fact used ... yikes!! Talk about overkill, no wonder the bolt sheared. Heat breaks down red loctite, but label says 450F for 5 minutes. If you can get a narrow flame just on the sheared bolt, it might work if you can heat it up enough. Just keep in mind the aluminum head is a massive heat sink, so do not use a wide flame. Focus heat just on the bolt. You might want to alternate between heat and drilling, with more heating than drilling. The goal really is to spin the bolt out, not drill it out. In general proceed very carefully, as you do not want to drill out the threads here.
Welding a nut to the bolt is probably the best & safest route here due to the red loctite. The welding heat alone should be enough to break the loctite bond and let you turn the bolt out with a socket.
![Image]()
![Image]()
Cannot emphasize enough how helpful left hand drill bits will be here as they turn in the direction that loosens the bolt, and everytime the bit catches it will act like an impact working to loosen. Regular drill bits will act to tighten the bolt and work against you. I linked to a stubby (mechanics) left hand drill bit set below that should work.
Just saw that red loctite was in fact used ... yikes!! Talk about overkill, no wonder the bolt sheared. Heat breaks down red loctite, but label says 450F for 5 minutes. If you can get a narrow flame just on the sheared bolt, it might work if you can heat it up enough. Just keep in mind the aluminum head is a massive heat sink, so do not use a wide flame. Focus heat just on the bolt. You might want to alternate between heat and drilling, with more heating than drilling. The goal really is to spin the bolt out, not drill it out. In general proceed very carefully, as you do not want to drill out the threads here.
Welding a nut to the bolt is probably the best & safest route here due to the red loctite. The welding heat alone should be enough to break the loctite bond and let you turn the bolt out with a socket.
Wow thanks a lot @LeverThis @westrumjr @A930rocket
When I saw some blue loctite on the bolt, I had a brain fart and applied a bit of new red loctite I have before reassembling... Not a bright idea...
Went to grab some tools at HF this afternoon:
The right-angle drill fits when removing the passenger side headlight assembly.
For the last hour, I've been going in reverse with the smallest drilling bit and then in reverse with the extractor bit and heating for a while with the torch, but the bolt won't budge.
@LeverThis saw it coming: I probably drilled too much now. I'll get the VANOS assembly out - screenshot from 50sKid VANOS video showing the bolt head.
![Image]()
Once the VANOS is out, I'll assess the situation. I have a friend that has welding tools, might have to borrow them.
How about tapping the drilled bolt and using a small helicoil + a small hex cap screw?
When I saw some blue loctite on the bolt, I had a brain fart and applied a bit of new red loctite I have before reassembling... Not a bright idea...
Went to grab some tools at HF this afternoon:
The right-angle drill fits when removing the passenger side headlight assembly.
For the last hour, I've been going in reverse with the smallest drilling bit and then in reverse with the extractor bit and heating for a while with the torch, but the bolt won't budge.
@LeverThis saw it coming: I probably drilled too much now. I'll get the VANOS assembly out - screenshot from 50sKid VANOS video showing the bolt head.
Once the VANOS is out, I'll assess the situation. I have a friend that has welding tools, might have to borrow them.
How about tapping the drilled bolt and using a small helicoil + a small hex cap screw?
The red loctite not only on the threads but also got inside the structure of the bolt, as shown in pic. Bolt was cracked before adding red loctite?
it's far easier to take the vanos out anyway and work in a relaxed way to take out the bolt, even a machine shop will probably do it for free if you take it there.
you sure the threads are messed? if so, timesert.
you sure the threads are messed? if so, timesert.
I agree with the rest that say use heat at least to get rid of the loctite, but if you see on the edges of that bolt, it looks like you can maneuver a small thin plier or even the tips of small tweezers (yes, for the eyebrows, or something similar) & use those 2 fine thin tip/points to put them in those small groves and once u feel the points snugged in there, try to turn it CCW to see if little by little it turns.
Success! By planting a torx bit in the drilled hole and then holding a heat gun close to the bolt at 500F for 5 minutes, I was able to slowly unscrew it right after that. The loctite totally melted at this point! The threads are all fine, even though I didn't do a super precise job drilling the bolt when the VANOS was still mounted. I easily fitted a brand new M6 bolt in there after cleaning the hole with acetone. Thanks a lot guys!
![Image]()
![Image]()
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
