Dropped camshaft sensor bolt--what now?

[argus]

Hi all,

So, the past several days, I have been working on replacing the intake manifold gasket along with the valley cover gasket, knock sensors, valve cover gaskets, and, while I'm at it, I figured I'd replace the camshaft position sensor and the oil pressure sensor because why not.

Everything was going smoothly (if extremely slowly--it took a long time to clean all the gunk off everything) until I went to remove the camshaft position sensor. I removed the bolt and somehow like a moron watched in slow motion as it fumbled out of my fingers and dropped somewhere behind the block, I think onto the passenger's side of the bellhousing. Now, for even dumber reasons that I can't explain, rather than immediately stop and look for the bolt, I kind of shrugged it off, thinking that it probably wound up on the ground and moved on to other things (re-installing the valley cover gasket).

Several hours of work passed and then I realized--shit! The bolt! and tried looking for it. Not anywhere on the ground that I could find. (D'oh!!!) I looked as much as I could, gave up, and bought a cheap-ish ($100) Actron borescope from a local parts store. No luck with this either. (Also, I wouldn't recommend that anyone buy this borescope--it's kind of a *************, image quality wise.)

I have a nagging thought that maybe I was so stupid that I let the bolt fall into the valley and put the cover plate on without realizing it (but I think that the probability of this is really slim...)

Is there some kind of netherworld/black hole/alternate dimension that I should be aware of around the bell housing into which this bolt could have fallen that I should check for?

There's a heat shield on the passenger's side of the transmission that I removed. I also removed the plastic guard panel thing that sits under the oil pan. I've looked/felt around in the crossmember that's under the oil pan. I was able to look on top of the transmission by putting my head next to the driveshaft.

Any ideas...? Monkey's paw? Turn the car over? Give it a shake?

 

[treehan77]

Have you tried a magnet on a stick tool?

 

[randeez]

Hi all,

So, the past several days, I have been working on replacing the intake manifold gasket along with the valley cover gasket, knock sensors, valve cover gaskets, and, while I'm at it, I figured I'd replace the camshaft position sensor and the oil pressure sensor because why not.

Everything was going smoothly (if extremely slowly--it took a long time to clean all the gunk off everything) until I went to remove the camshaft position sensor. I removed the bolt and somehow like a moron watched in slow motion as it fumbled out of my fingers and dropped somewhere behind the block, I think onto the passenger's side of the bellhousing. Now, for even dumber reasons that I can't explain, rather than immediately stop and look for the bolt, I kind of shrugged it off, thinking that it probably wound up on the ground and moved on to other things (re-installing the valley cover gasket).

Several hours of work passed and then I realized--shit! The bolt! and tried looking for it. Not anywhere on the ground that I could find. (D'oh!!!) I looked as much as I could, gave up, and bought a cheap-ish ($100) Actron borescope from a local parts store. No luck with this either. (Also, I wouldn't recommend that anyone buy this borescope--it's kind of a *************, image quality wise.)

I have a nagging thought that maybe I was so stupid that I let the bolt fall into the valley and put the cover plate on without realizing it (but I think that the probability of this is really slim...)

Is there some kind of netherworld/black hole/alternate dimension that I should be aware of around the bell housing into which this bolt could have fallen that I should check for?

There's a heat shield on the passenger's side of the transmission that I removed. I also removed the plastic guard panel thing that sits under the oil pan. I've looked/felt around in the crossmember that's under the oil pan. I was able to look on top of the transmission by putting my head next to the driveshaft.

Any ideas...? Monkey's paw? Turn the car over? Give it a shake?

drop another bolt in the same location and see where it falls

dunno i guess the question is really is it in the engine or the bellhousing? you could prob take the starter out if theres no other way to see in the bellhousing and use that scope to check it out.

engine- pull the valley cover back off or turn it over by hand and hope it falls into the pan

 

[SnowDrifter]

If it's not inside the engine, honestly, grab a new bolt and say **** it

 

[argus]

So, in case anyone was wondering how this turned out: I never did find the bolt, and just replaced it with one from the hardware store.

If anyone needs the info, the bolt for a GM Gen III small block camshaft position sensor is an M8x1.25, 20mm long flange bolt. A 25mm bolt is too long; it bottoms out in the threads. Note that the bolt from the factory has a (smaller than normal) 10mm head, whereas the hardware store variety bolt that I used was either 12 or 13mm (I don't recall) but worked just fine: there was plenty of room between the sides of the head & the flange and the camshaft position sensor.

Anyway, I was pretty happy with how the result turned out: I was motivated to do this because there was oil dripping down the back of the block especially and off of the starter bolts, and the motor was constantly throwing lean colds in cold weather. The leaks seem fixed and the lean codes have not returned, and the engine runs significantly more smoothly, most noticeably when starting from cold. Before, it would almost (or actually) stall out in cold weather, and the idle air control valve would have to "hunt" around to try to keep the motor from stalling; now it near-instantly hits 1k RPM after starting and stays there, even in cold weather.

View media item 27607View media item 27609View media item 27608

 

[treehan77]

So which part was your leak? Mine leaks down the back and onto the starter bolt also, and on the other side some as well. I’ve changed the oil pressure switch already, but that’s it.

 

[argus]

So which part was your leak? Mine leaks down the back and onto the starter bolt also, and on the other side some as well. I’ve changed the oil pressure switch already, but that’s it.

It's hard to say what the most significant leak was, but I'll note that the (factory original) oil pressure sensor was not screwed in very tight, so that might have been the bulk of what I was seeing down the back. The valley cover gasket seemed to be leaking because, for all ten of the bolts that secured the valley cover in place, the threaded holes in the block had an appreciable amount of oil in the bottom of them (which I cleaned out with brakleen and q-tips), and the gasket was wet with oil past the rubber portion of the gasket and onto the metal portion (which should stay bone dry if the gasket isn't leaking, I think). Each bolt hole in the gasket is surrounded by its own bit of rubber, so the bolts should have all been dry also.

I could see that the back of the block was wet with oil from the valley down, which seems to back this up. The valve covers were also horrendously filthy, and the grommets on the valve covers broke apart when I tried to take them off, so I don't doubt that those were leaking, too.

I will note that my oil pan is also leaking like a sieve, despite the fact that I've replaced that once already. I suspect that, because the oil pan is structural (the lower two transmission bell housing bolts go into the pan), under a heavy load (accelerating quickly, towing), the bell housing torques the pan and causes it to (momentarily?) leak oil (???--could anyone confirm this?)

I should admit that it's only been a week and a half or so (I forget) since I did the repair, so perhaps I shouldn't say the leak is totally fixed (oil pan aside) yet. When I did the pan gasket for the first time, it stayed bone dry for all of about a month before showing signs of leaking. (I guess I didn't clean the mating surfaces well enough??? I did RTV the four corners.)

I don't think I have a rear main seal leak because when I changed the pan gasket, the flexplate looked dry. (But, that was 2 years ago.)