gray635

I'll be the first to acknowledge that I'm no mechanic, but I've spent a frustrating morning on what I thought would be the simple task of replacing my stock air filter. I've wrenched on plenty of old BMWs (got a 1988 M5 and and 1985 M635CSi now and on both of those cars, you've got to remove the entire air filter box/AFM assembly to do the replacement, but still very straightforward).

Anyway, this has got to be one of the all-time poorest automotive designs for access (or lack thereof) to a standard service component. Almost no clearance. I finally took the AFM/air filter box assembly off and discovered that both of the tabs on the inner half of the air filter box had broken and would not hold the clamps, one of which was missing anyway.

So after some twisting and forcing, I finally got the air filter box back on the car, held in place with only the two outside clamps, with the rear obviously poorly sealed. I've done some searching but cannot find an aftermarket solution for replacing the entire air filter box in my car. I am very reluctant to use a cone K&N but may have to go that route. Looks like FabSpeed sells a cut-out filter frame but, because of the broken tabs on the inner half of my box, I'd have to replace that to use the FabSpeed piece. Any suggestions from the forum would be much appreciated!

greg1990964

I think I have 2 or3 tabs holding mine on still, and it does the job of sealing it up around the edges. Takes a little bit of wrangling. The rear tab takes practice to get on and not drop behind as mine is not held in place on its own. I keep my magnet tool handy. Also, take off oil cap when pulling out the cover, much easier. It is hard to find replacements that are stock and not drilled w/o paying alot of money. I bought a spare cover to use as my drilled one and kept my original one unmolested. Not to start a thread on the sound difference of a drilled box, but it does sound pretty sweet at WOT. I drilled each square with a hole saw bit, that way it is only smaller holes about a inch and not excesive.

Steve Weiner-Rennsport Systems

While the OEM airbox cover isn't the easiest thing to deal with, installing a filter cone in its place would be a self-destructive "solution".

I'd kindly recommend getting another good used airbox without any broken hold-own clips instead of any kind of cone filter. This will ensure that your (expensive) engine continues receiving clean air and leave the cone filters for race engines that get rebuilt every few years.

IMHO, the clips get broken due to human factors more than anything else.

Babalouie

Cutting the horn off the airbox improves power (very) slightly, releases a more pleasant induction sound, and gives you increased Rennlist coolness points


Improves access no end too Now the cover can come off without scraping across 50% of the things in the engine bay

gray635

Thanks for the insights. I've never been a K&N fan and certainly do not want to take that approach.

Yeah, I took off the oil filler cap and that did improve access somewhat. I'll probably just look for a nice half of the air filter box that mounts to the AFM with the clamp tabs intact and try the RSA approach to the other half of the unit. Is the FabSpeed part the best choice for that or are there other options? Any other ideas would be appreciated.

g60pops

The fabspeed cover does not seal up so well at the back

Steve Weiner-Rennsport Systems

That one is to be avoided due to QC issues.

Get the OEM Porsche airbox and modify the cover to suit.

newsboy

If you wanted to try a repair? Put two small sheet metal screws where the broken of tab was. Then build up with a two-part epoxy to get the shape of the tab that will hold the clip. Just an experiment, but maybe worth trying before purchasing a new air box.

cobias1

I think there is one on Ebay right now. Not sure about the condition though.
Dan

gray635

Well, I wound up cutting the face off the air filter cover. It certainly improves access but is not exactly an elegant solution to the problem!

I will probably just search the breakers and see if I can find a nice, used air filter box and locate a friend with VERY small hands.

If anyone knows a proper aftermarket solution for this (other than K&N and FabSpeed), please let me know. Thanks for the assistance so far!

vagluv

why not get the k&n drop in style? thats what i have

cobias1

DCAuto shows one in stock for 75.00.

gray635

DC Auto has the filter box cover only - $75.00. Ordered it earlier this afternoon after calling to confirm that they didn't have the entire assembly in stock. Autobahn Recycling in CA has the base on eBay for $175, and I bought it this afternoon as well. Ordered new clamps from Pelican. So I'm trying to piece a replacement together!