Help locating where 2 aluminum bolts go in the underfloor/underhood shield/belly pan

psubmw · 11-13-2015, 08:22 AM

I need help locating where 2 bolts are installed in the underhood/underfloor/belly cover/shield. I think the bolts I have in the attached picture are #4. Does anyone have a closer view of #1, the underhood shield, so I can determine where my 2 leftover bolts are installed? I have a 335xi with msport package.

hassmaschine · 11-13-2015, 08:38 AM

I don't think any of those bolts are aluminum. They are all steel on both of my cars.

There are several right at the corners in the front of the shield that can be tricky to see. If you have leftover bolts and they are aluminum, they go somewhere else, but if they are steel then you'd have to look for leftover holes..

psubmw · 11-13-2015, 09:11 AM

Maybe they are steel. It's hard to tell.

psubmw · 11-13-2015, 02:46 PM

Are there more detailed drawings somewhere?

PhaseP · 11-13-2015, 06:39 PM

Quote:

Maybe they are steel. It's hard to tell

Aluminum will feel very light compared to same size steel bolts.
You can also try a magnet, if sticks it is steel.
Though some stainless steel is not magnetized but I don't think they use any stainless steel, due to cost there.

Most steel bolts BMW uses has a coating that is dull grey.

Can you post a picture?

psubmw · 11-16-2015, 03:09 PM

Sorry for the long wait!

The bolts are not aluminum. They must be steel since they are magnetic. Here is a picture, for what it's worth.

PhaseP · 11-17-2015, 12:25 PM

It does look like bolt 4 on the diagram. You are then missing the washer number 5 too.
Mine has all sheet metal thread screws of number 8 on the diagram on the undercover. Don't remember taking out any machine threaded bolts like yours.
But mine is 2006 325 xi with no msport.

psubmw · 11-17-2015, 01:37 PM

Yea, I thought it was all of type 8 too. I guess I'll have to look around and see if maybe it's from something underneath (above) the cover.

kiel_dafo_kenyg_as · 11-17-2015, 02:14 PM

You did not mention what size they are. No such bolts on the belly cover at least on European models. What kind of repair did you perform? Have you just found the bolts or did you unscrew them from somewhere? They're not hex bolts like #4 are. They're torx heads. The only torxes I remember that may look like these are on the exhaust system support.

psubmw · 11-17-2015, 05:47 PM

These are leftover from when I cleaned my intake valves on my N55. Everything is running great. There are no rattles or CELs. The reason that I had the belly pan off is that I had dropped a bolt (PITA!!!!!!!!!!!!). Removing the pan seemed like the most likely way to find it. Of course, the bolt I dropped was somehow no where near where logic would suggest...

The bolts look like the shaft is 1" or approximately 25mm in length, as I have measured. I do believe that the head is a metric M6. Therefore, I am led to believe that it is a M6x25 bolt, with a hex head (not inverted torx).

I have looked around everywhere underneath the car for a place where these 2 bolts might go, and as I thought and a few have mentioned, all the fasteners look like they should all be the short, black, typical belly pan fastener.

On the N55, the DME is attached to the intake manifold. Although I never removed the DME from the intake manifold, I wonder if maybe I removed these 2 bolts because the parts drawing suggests that part of it is held on by 2 bolts that are M6x25. I guess I'll look there next.

PhaseP · 11-17-2015, 07:44 PM

You probably found them. It says it is a self tapping screw. If yours have triangular lobed cross section, they would be self tapping too, and then likely those. The triangle cross section is one way I know of self tapping screws. They also have a slight taper at the end. They are easier to cross thread though by mistake when reusing on already tapped hole, at least in my experience.

I just removed belly pan to check for oil leak on the oil pan. The only thing I saw hex and that looked similar to your pictures in that area were the sway bar bracket bolts.

psubmw · 11-17-2015, 10:08 PM

Yea, we'll see. The bolts aren't tapered though I can't see why they would be self tapping to attach the dme. I guess I'll find out tomorrow when there is some light.

They definitely aren't part of the belly pan though! Haha

psubmw · 11-22-2015, 07:40 PM

Those two bolts were some of the fasteners holding the dme to the intake manifold. Fantastic. It's finally all back together without any leftovers.

PhaseP · 11-24-2015, 10:56 PM

Good to hear, and thanks for closing the thread with the result.

11-13-2015, 08:22 AM	#1
psubmw Second Lieutenant 28 Rep 277 Posts Drives: 335i Join Date: Mar 2010 Location: Delaware iTrader: (2)	Help locating where 2 aluminum bolts go in the underfloor/underhood shield/belly pan I need help locating where 2 bolts are installed in the underhood/underfloor/belly cover/shield. I think the bolts I have in the attached picture are #4. Does anyone have a closer view of #1, the underhood shield, so I can determine where my 2 leftover bolts are installed? I have a 335xi with msport package. Attached Images Last edited by psubmw; 11-13-2015 at 02:46 PM..
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11-13-2015, 08:38 AM	#2
hassmaschine Major General 3973 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	I don't think any of those bolts are aluminum. They are all steel on both of my cars. There are several right at the corners in the front of the shield that can be tricky to see. If you have leftover bolts and they are aluminum, they go somewhere else, but if they are steel then you'd have to look for leftover holes..
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11-13-2015, 09:11 AM	#3
psubmw Second Lieutenant 28 Rep 277 Posts Drives: 335i Join Date: Mar 2010 Location: Delaware iTrader: (2)	Maybe they are steel. It's hard to tell.
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11-16-2015, 03:09 PM	#6
psubmw Second Lieutenant 28 Rep 277 Posts Drives: 335i Join Date: Mar 2010 Location: Delaware iTrader: (2)	Sorry for the long wait! The bolts are not aluminum. They must be steel since they are magnetic. Here is a picture, for what it's worth. Attached Images Last edited by psubmw; 11-16-2015 at 03:15 PM..
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11-17-2015, 12:25 PM	#7
PhaseP Colonel 1007 Rep 2,108 Posts Drives: 325XI Join Date: May 2010 Location: Earth iTrader: (0)	It does look like bolt 4 on the diagram. You are then missing the washer number 5 too. Mine has all sheet metal thread screws of number 8 on the diagram on the undercover. Don't remember taking out any machine threaded bolts like yours. But mine is 2006 325 xi with no msport.
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11-13-2015, 02:46 PM	#4
psubmw Second Lieutenant 28 Rep 277 Posts Drives: 335i Join Date: Mar 2010 Location: Delaware iTrader: (2)	Are there more detailed drawings somewhere?
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11-17-2015, 01:37 PM	#8
psubmw Second Lieutenant 28 Rep 277 Posts Drives: 335i Join Date: Mar 2010 Location: Delaware iTrader: (2)	Yea, I thought it was all of type 8 too. I guess I'll have to look around and see if maybe it's from something underneath (above) the cover.
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11-17-2015, 02:14 PM	#9
kiel_dafo_kenyg_as DIE ANTWOORD 68 Rep 640 Posts Drives: 335d E92 Join Date: Jul 2014 Location: Bimmer's home - Bavaria iTrader: (0)	You did not mention what size they are. No such bolts on the belly cover at least on European models. What kind of repair did you perform? Have you just found the bolts or did you unscrew them from somewhere? They're not hex bolts like #4 are. They're torx heads. The only torxes I remember that may look like these are on the exhaust system support. __________________ King of the road says you move to slow
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11-17-2015, 05:47 PM	#10
psubmw Second Lieutenant 28 Rep 277 Posts Drives: 335i Join Date: Mar 2010 Location: Delaware iTrader: (2)	These are leftover from when I cleaned my intake valves on my N55. Everything is running great. There are no rattles or CELs. The reason that I had the belly pan off is that I had dropped a bolt (PITA!!!!!!!!!!!!). Removing the pan seemed like the most likely way to find it. Of course, the bolt I dropped was somehow no where near where logic would suggest... The bolts look like the shaft is 1" or approximately 25mm in length, as I have measured. I do believe that the head is a metric M6. Therefore, I am led to believe that it is a M6x25 bolt, with a hex head (not inverted torx). I have looked around everywhere underneath the car for a place where these 2 bolts might go, and as I thought and a few have mentioned, all the fasteners look like they should all be the short, black, typical belly pan fastener. On the N55, the DME is attached to the intake manifold. Although I never removed the DME from the intake manifold, I wonder if maybe I removed these 2 bolts because the parts drawing suggests that part of it is held on by 2 bolts that are M6x25. I guess I'll look there next. Attached Images
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11-17-2015, 07:44 PM	#11
PhaseP Colonel 1007 Rep 2,108 Posts Drives: 325XI Join Date: May 2010 Location: Earth iTrader: (0)	You probably found them. It says it is a self tapping screw. If yours have triangular lobed cross section, they would be self tapping too, and then likely those. The triangle cross section is one way I know of self tapping screws. They also have a slight taper at the end. They are easier to cross thread though by mistake when reusing on already tapped hole, at least in my experience. I just removed belly pan to check for oil leak on the oil pan. The only thing I saw hex and that looked similar to your pictures in that area were the sway bar bracket bolts.
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11-17-2015, 10:08 PM	#12
psubmw Second Lieutenant 28 Rep 277 Posts Drives: 335i Join Date: Mar 2010 Location: Delaware iTrader: (2)	Yea, we'll see. The bolts aren't tapered though I can't see why they would be self tapping to attach the dme. I guess I'll find out tomorrow when there is some light. They definitely aren't part of the belly pan though! Haha
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11-22-2015, 07:40 PM	#13
psubmw Second Lieutenant 28 Rep 277 Posts Drives: 335i Join Date: Mar 2010 Location: Delaware iTrader: (2)	Those two bolts were some of the fasteners holding the dme to the intake manifold. Fantastic. It's finally all back together without any leftovers.
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11-24-2015, 10:56 PM	#14
PhaseP Colonel 1007 Rep 2,108 Posts Drives: 325XI Join Date: May 2010 Location: Earth iTrader: (0)	Good to hear, and thanks for closing the thread with the result.
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