[Bimmer221]

I was changing the crankshaft position sensor and somehow the nut fell into the hole where the sensor sits. Is there anyway to get the nut out without taking apart the engine? Like if i release the oil will it come out, or is it not connected? Help would be appreciated. its in a 2009 328i Thanks!

[Captain comic]

Originally Posted by Bimmer221

I was changing the crankshaft position sensor and somehow the nut fell into the hole where the sensor sits. Is there anyway to get the nut out without taking apart the engine? Like if i release the oil will it come out, or is it not connected? Help would be appreciated. its in a 2009 328i Thanks!

IMHO you need magnetic pick-up tool, but it has to be thin enough to fit through crankshaft position sensor hole. Something like this: http://www.autozone.com/test-scan-an...?checkfit=true

Measure hole diameter and buy magnetic pick-up tool that will fit - it is by far easiest and cheapest way to solve this issue (tho it will require some time to catch that nut). AFAIK nut will not come out simply by draining oil and dropping an oil pan is not the easiest/cheapest way either

[CTinline-six]

+1 on the magnetic pick-up tool. They make some pretty thin ones that are still really strong. Mine has saved my butt a couple times.

[Bimmer221]

Just ordered a magnetic pick-up tool from amazon. But is the sensor hole also connected to the oil pan? If I drain the oil and dump some more oil in will there be a chance for it to fall out?

[hassmaschine]

unfortunately that bolt is aluminum, because it threads into the magnesium block - so a magnetic tool isn't going to help.

I would drain the oil and remove the oil level sensor, and see if you can remove the bolt from that hole.

[Bimmer221]

aw dang. I'll just have to try removing the oil level sensor and try fishing it out from the oil pan then

[Captain comic]

If you ordered pick-up tool with claws - it's still worth a try, I'm just not sure if you'll be able to access bolt via drain hole as I thought there is something in between

[Bimmer221]

Ya i also thought there was something between, but multiple people are telling me to drain oil and it should come out :/. I hope that works

[avocet]

maybe try and boroscpe the opening and see if it has a clear shot down into the sump... or maybe see if it has landed on something down in there.



this is one of the more affordable units around and has an 8.5mm head diameter...maybe it will fit. that is pretty small you gotta spend $$$ to get much smaller than that. BTW this is from a cdn wesite so harbor freight or such should have one cheaper...
https://www.kmstools.com/autel-video...-camera-102850

[Eddien123]

Wow man that's a tough break. Good luck and let us know. I would probably recommend draining the oil to see if you can fish it out or if it just falls out.

[Efthreeoh]

OP, let me throw in. I've had the oil pan off of my N52 so I'm familiar with this area of the engine. I remember seeing the transducer side of the crank position sensor sitting in the block. What I can't remember is the position of the hole it fits in if it was below or above the oil windage tray that sits below the crankshaft. The pic below shows the windage tray. My concern is if the bolt fell in the hole did it fall onto the windage tray (then it won't be sitting in the pan), or did it drop into the pan. According to realOEM the bolt is aluminum, so forget about a magnetic tool picking it up. Good news is the sensor is at the back of the block where the deepest part of the oil pan is, so if the bolt fell into the pan, it's near the oil sensor.

I think the advice you got here in parts is good, but I'd put it all together. Here's what I'd do:
- Rent an automotove borescope from a tool rental place or maybe autozone has one.
- Drain the engine oil
- Put the borescope into the sensor hole and see if the hole is above or below the oil windage tray
- If the hole is blow the tray, then remove the oil sensor (I published a DIY on how to remove and replace it)
- The opening for the oil sensor is about 1.5 inches so there is plenty of room to fish around for the dropped bolt.

If the hole is above the windage tray (I think it is), then you'll have to drop the oil pan, remove the oil pickup tube, remove the windage tray and then find the bolt.

All that said, are you sure the bolt fell into the hole, or did it just drop down on to the belly pan, or get lost somewhere in the subframe somewhere?

Good luck with it.

[Captain comic]

Maybe if he can locate bolt with boroscope - he can then try to fish it with magnetic pick-up tool that has claws - it's used to pick up items exactly like that, that are non magnetic. I'm just repeating it only because it's a lot easier than dropping the pan and all that stuff

[Efthreeoh]

Originally Posted by Captain comic

Maybe if he can locate bolt with boroscope - he can then try to fish it with magnetic pick-up tool that has claws - it's used to pick up items exactly like that, that are non magnetic. I'm just repeating it only because it's a lot easier than dropping the pan and all that stuff

If it is in the pan, it will be easy to get to once the oil level sensor is removed as Hassmachine suggested (Hassmachine knows the N52 better than anyone on E90 Post IMO). With a claw tool, I just don't see how it will be possible to find the bolt and get the claws on it pick it up and then get it back out of the hole. IIRC the crank sensor hole is above the windage tray because the sensor pickup is literally right next to no.6 cylinder crank throw where the toothed wheel is. The sensor toothed wheel is right behind the No. 6 piston rod bearing. I thought I had a pic of it, but I don't. It's easy to figure out. The block has a bed plate between the upper block and the oil pan seam. The split between the upper block and the bed plate is at 180 deg. on the crank. In other words, the the top 180 deg. of the crank sits in the upper block and the lower 180 deg sits in the bed plate. From the schematics on realOEM it shows the crank sensor on the upper block side above the bed plate. The windage tray bolts to the bottom of the bed plate below the crankshaft.

The windage tray has a gap between it an the wall of the block maybe about two inches wide and IIRC the sensor pickup was above the tray, hopefully there is a good chance that the bolt dropped into the pan. But considering the engine is tilted about 30 deg. counter clockwise, the crank sensor hole is on the high side of the block because it is located on the left side of the block. Everything inside the engine tilts downward to the right side of the engine. The bolt, if it fell in the crank sensor hole, might have not drop down into the oil pan. Maybe the OP gets lucky and it did drop into the pan, but I'd plan that it didn't. Best case is the bolt dropped and rolled across the windage tray and is sitting on the right side of the block on the windage tray right above the seam where the pan attaches to the bottom of the block.

If it were my car, I'd first get a boroscope and pull the oil level sensor and look around. Next I'd drop the pan to find the bolt if I was absolutely sure that the bolt fell into the sensor hole in the block.

This is the same issue I have concern about when people remove the VANOS sensors, you can drop the hold down bolts into the timing chain case. The best practice is to remove the hold down screws from both the sensors and place them away from the engine bay. Then remove and replace both sensors, then bring the hold down bolts back into the engine compartment and tighten down the sensors.

[hassmaschine]

oh man. I totally forgot about the windage tray. I think most likely, it's not in the pan, but sitting on that tray - it fits pretty tightly to the crankshaft.

But, the level sensor is easy enough to remove, so yeah, I'd start there and cross your fingers..

[danas]

Use the boroscope. Then if you can connect a small hose to the shop vac and hopefully that will pick up or at least stick to the suction..

[Efthreeoh]

Originally Posted by hassmaschine

oh man. I totally forgot about the windage tray. I think most likely, it's not in the pan, but sitting on that tray - it fits pretty tightly to the crankshaft.

But, the level sensor is easy enough to remove, so yeah, I'd start there and cross your fingers..

So I got to thinking about this a little more. The gap between the block wall and the toothed wheel is not much (obviously the depth of the sensor head less the block wall dimension). I'm not familiar with the size of the sensor hold down bolt, but maybe the bolt didn't even fall into the block at all and is just sitting in the hole lodged against the toothed wheel. The hall-effect transducer that makes the signal for the sensor has to be a millimeter or less away from the toothed wheel so there is not much space for the bolt to just drop in the hole. The cross-dimension of the toothed wheel is about the same as the diameter of the transducer head, and the hole is probably just a few millimeters bigger than that, which again makes me think the bolt is just sitting in the hole, or dropped into the pan.

That said, it's possible that if the bolt did get through the hole the toothed wheel kept it from rolling across the windage tray and actually did make it drop straight down into the block. I don't think you can get a boroscope through the hole past the toothed wheel. So I think the only way to look into the oil pan without removing the oil level sensor is to drain the oil and go in through the oil drain hole. You'd get a good view of the deep part of the pan that way, but I still think as you originally suggested, the only way to get the bolt out if it is in the pan, is to remove the oil level sensor.

[Captain comic]

OP please update us on this - I'm interested to see how this drama will end

[Bimmer221]

I'm looking at some boroscopes currently and hopefully i have time this weekend to try to get this sorted out.

[Bimmer221]

How difficult is it to drop the oil pan and windage tray to try to get to the bolt? would i need a lift?

[Efthreeoh]

Originally Posted by Bimmer221

How difficult is it to drop the oil pan and windage tray to try to get to the bolt? would i need a lift?

There is a really good DIY in the DIY section on replacing the oil pan gasket. A lift is not necessary but way easier. The windage tray will need a new bolt set, realOEM has the part number. The oil pump pick tube and tray just unbolt from the bottom of the block.

[pruettfan]

Originally Posted by Bimmer221

How difficult is it to drop the oil pan and windage tray to try to get to the bolt? would i need a lift?

Dropping the pan isn't for the weak hearted. A lift makes it way easier, you really need to remove the subframe which means its not the safest job to do if you don't have the right equipment and skills. I would try the borescope and go from there. If there are no signs of it you may want to consider paying a pro. I did all of the work on my 330i up until I was faced with doing the oil pan gasket, for 800 bucks I had a pro do it, wasn't cheap but when I looked at doing the job it wasn't for me. BTW I have done brakes, starter, alternator, tensioners, AC compressor, water pump, valve cover gasket etc etc so I feel comfortable with most jobs.

[Efthreeoh]

Originally Posted by pruettfan

Dropping the pan isn't for the weak hearted. A lift makes it way easier, you really need to remove the subframe which means its not the safest job to do if you don't have the right equipment and skills. I would try the borescope and go from there. If there are no signs of it you may want to consider paying a pro. I did all of the work on my 330i up until I was faced with doing the oil pan gasket, for 800 bucks I had a pro do it, wasn't cheap but when I looked at doing the job it wasn't for me. BTW I have done brakes, starter, alternator, tensioners, AC compressor, water pump, valve cover gasket etc etc so I feel comfortable with most jobs.

I have to agree with pruettfan. I did my oil pan gasket on a lift and while not super difficult, it's just tedious. Like pruettfan says, you need special equipment such as an engine brace (I made mine out of wood), several jacks (floor and transmission jack - I have both). You don't have to completely remove the subframe, but you have to drop it from the chassis and let it hang, and with it dropped the room under the car if on stands is pretty tight unless you can get the car some 3 feet in the air, which then call for a high-lift floor jack and tall stands, all which can be rented of course for a price.

Then getting the pan out takes some manipulation, which if just on stands would be a pain in the ass. There's not a lot of room to get the pan to clear the oil pump when the subframe is dropped.

OP, again, are you sure the bolt fell in the hole?