911Jetta

So I have had a couple minutes to spare before the kids got home and thought I would quickly change the air filter...

Most of the spring-time pollen had fallen already and the filter box on the workbench kept staring at me. This should just take a couple minutes, right?

Wow it's tight in there...unclipped the airbox and wiggled everything out. Then I saw a bolt laying close to the fuel rail. Had a quick look around and didn't see any place for it to go, so I moved on...then I just happened to see another bolt. The same type! Ok now I'm getting a little worried. Two big bolts just laying on top of the engine? I look up and saw a similar bolt attached to the intake horn inside the airbox. Yes, the two fallen bolts fit on the backside of the intake horn. Now, how do I get back there? The backside top bolt was near impossible to re-attach. Going almost blind, I had a 10 mm socket extension in one hand, flashlight and mirror in the other hand...very, very tight and hard to access.

Extra notes:
- the old filter was very dirty after only a year+ time. (do you guys replace yours annually?)
- removing the oil filter cap gives you a little more space to remove/install the filter assembly.
- if you don't have these tools already: a magnetic pen tool helps loose/dropped bolts in the engine bay, and a adjustable mirror tools is also invaluable!

Rocket Rob

The factory attaches the air box using 6mm studs, not bolts. But I'm sure bolts would be fine too.

As for how often to change the air filter? The factory recommends every 15K miles. That frequency seems sufficient to me. Do you drive in dusty areas?

911Jetta

See the gold colored bolts (ah, studs) in the third picture above. That's what I re-installed. Definitely 10 mm also. The two loose bolts perfectly matched those bolts (thank you mirror tool), but given the million bolts, wires, etc. in the engine bay I don't know for sure? The loose bolts were also in the same area as the air box; they were probably held in place by the air filter and finally came out when I removed the filter. I hope that's right anyway...

Other than pollen, it don't live in a dusty area. Since the filter is so cheap I thought I would go ahead an replace it after about 7,000 miles (15 months). It was very dirty in the folds of the filer also.

elbeee964

Hee-hee...
You're gonna love this one: That air inlet 'horn' that's in your way, snaps into place in the air box.
So, push in the side of the horn most exposed, and lever/unsnap the horn from the box.
Now every bolt's exposed.
When you're done, just snap that horn back into place.
Simple!

It's really a cool design once you see it.

Now, if all four of those air box bolts are in there - and you have two extra still sitting in your hand?...
Well, look around some more, because the Porsche designers just luuuuv that 10mm bolt design; and use it. A lot.
Good luck, Mr. Phelps.

[this thread entry sizzling]

911Jetta

Lonnie, I'm glad you're the one that broke the news to me...your humor goes a long way in this situation.

I was wondering if there was a simpler way...it just seemed too tight of a spot to put a bolt?

It sucks to be a newbie! Every 5 minute job turns into a 1 hour project.

All four bolts are accounted for! It's a hassle getting the filter out, but you know I've got to checkout the snap feature...

911Jetta

I see it now... the tab between the two bolts. If I wouldn't have needed a flashlight and mirror tool just to see inside the airbox I might have found the tab...well probably not.

elbeee964

Yup. That's the one.
It has a twin on the other side, as I recall, but only one of them needs be slightly pushed in to clear that airbox tab... finger compression will do it... then lever out the whole horn from its snapped-in socket position.

Garret376 once showed me stuff over at his house when I was still a newby. His one morning's troubleshoot of my car exposed me to a quantum leap in disassembly/troubleshooting techniques. Now that dude has forgotten more about the 964 than I'll ever know.

crg53

Jetta, from the factory there are 4 studs in place of the bolts that you put in, and of cause 4 self locking nuts to hold the airbox in place.
My concern with your set-up is, nothing is securing those 4 bolts unless you used some kind of thread locking compound. I would just hate to see one of those bolts come out and get sucked into the engine.
My advice would be to go back to stock setup, or to put serviceable loctite on all 4 bolts.

911Jetta

Steen, thanks for the concern.

Everything is stock, I just replaced the air filter and found the two bolts (studs) laying on the engine. I think I found the correct home for the bolts...turns out I just did everything the hard way...

At least I found these bolts on the outside of the engine...not on the inside after pulling the crank case oil plug like here (933 forum): http:
//forums.rennlist.com/rennforums/showthread.php?t=567403&referrerid=19642 ...a good read and another great example of RLers willing to help.

Rocket Rob

Is this photo how you left it? Those bolts are not the stock studs. I agree with Steen, if you are going to keep them then you need to use a threadlocker (ie Loctite) on the bolts.

911Jetta

Keep in mind I come to this situation as a newbie, I found to bolts on the engine and nearby I found two threaded holes of the exact same size. My thinking was that that they worked their way loose over and only fell out after removing the air filter.

Wow, I thought I was done. Glad I took pictures and created a thread for fun! (also huge thanks for everyone's help)

I'm visual so I've attached a couple pictures, but I think I'm beginning to understand what Steen and Rob are saying.

I've been miss led by the two bolts that were holding the assembly in place. They are 10mm bolts and instead should be 6mm studs? Therefore at some point the 6mm studs were changed out for 10mm bolts?

Is this difference even possible given that the 10mm bolts tightened up nicely?

I see the studs you are talking about in this picture (also first picture below-blue gloves):
https://rennlist.com/forums/showthre...ferrerid=19642

ValveFloat

I don't know if this helps at all, but most likely those are 6mm bolts. You probably call them a 10mm because you use a 10mm wrench on them. Basically you have 6mm bolts threaded into holes that at one time had 6mm studs in them.

911Jetta

I found a picture of what you are talking about... (thanks dfinnegan)
https://rennlist.com/forums/3155883-post11.html

I think I can see the thread and stud you are talking about...
Given that the original studs are missing and I am now left with (4) 10mm bolts that thread into something...can I just remove the 10mm bolts, apply some blue loctite and call it a day?

Will the 10mm bolts that are there now secure everything...OR do I have to order 6mm studs and remove everything to get at the backside?

911Jetta

VF, your comments help!
I'm such a newbie...I was wonder the same thing?

I definitely used a 10mm wrench, but how could those bolts fit when everyone (who's much more experienced than me) keeps talking about 6mm studs...now I understand. Thanks again!

Rocket Rob

In the short term, yes, put loctite on the bolts you have. Long term, get some studs and replace the bolts, using loctite and then attach the air filter assembly to the studs with self-locking nuts.

Sorry for being confusing on the 6mm vs 10mm. The bolts you have have a 6mm thread and 10mm heads. If you buy studs, they will be called M6 studs which should 6mm x 18mm long. The nuts will be M10 nuts which are use a 10mm socket.