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Wednesday, October 4, 2023

Doug's Domain

Doug Vetter, ATP/CFI

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Wednesday, December 23, 2015

The Setup

I got a call one evening last week from my brother asking me about a friend's 2002 E46. He said that his friend had noticed a rattling noise coming from the front of the engine and his assessment, following a brief look under the hood, led him to suspect the fan clutch. The fan blades reportedly appeared to wiggle when moved 90 degrees to the direction of rotation (toward the engine or away from it).

I told him that the fan blades would wiggle that way under two conditions: the fan clutch was toast as he suggested or the water pump bearings were shot and the entire thing was about to come apart with potentially destructive force. When he clarified that the 32mm nut appeared to remain stationary I naturally assumed his original diagnosis to be correct but as I had never seen a clutch fail in this way I remained open minded. Always the skillful manipulator he asked if I could come take a look at it and perhaps help him acquire the necessary parts with my 20% dealer discount. Not fully realizing what he was really asking me to do at the moment I said what most good (and occasionally naive) brothers would say -- "Sure, see you tomorrow morning."

Because I knew replacing either the clutch or the water pump would require removal of the fan shroud and I had never done this on my own E46 I did some research on the subject. A few minutes later I had figured out that removal of the shroud would require removal of the cold air intake (3 plastic rivets and a tug out of the airbox) as well as removal of a screw and additional plastic rivet on the top of the shroud. The shroud, then, would be pulled out at the same time as the mechanical fan, which would in turn require the usual honkin' 32mm wrench and a hammer approach to excise.

The Plot Deepens

The next morning I drive over to my brother's house to see his friend's E46 near the entrance of the driveway...with a flat front tire. "Oh, yea, that happened this morning...can you grab your jack so we can pull the wheel off? We'll drop it by that tire place near the dealer", my brother said matter of factly as I exited my vehicle pointing at the tire and frowning. You can probably figure out what we did next but just in case you're wondering I'll point out that it is, in fact, possible to get the AFF200 under the E46 jack point (barely) when supported by a 1/4 inch sheet of plywood when the front wheel has sunk an inch or two into a gravel driveway.

With the wheel removed and thrown in the back of the pickup I popped the hood, confirmed that the clutch was in fact at fault, and ran over to the dealer with my brother to get the parts. Obviously used to buying parts for his largely domestic fleet he seemed stunned with the ~$205 charge (yea, with my discount). Long since brainwashed to believe this is perfectly normal I merely yawned and asked for a 32 cent plastic rivet to replace the one on the top of the shroud that I naturally assumed would break during removal. You could call me skeptical, but then you'd be ignoring my experience with these stupid things. I mean, com'on BMW. You already installed a screw on one side. What the hell was stopping you from using another screw?

Anyway, back at my brother's house we installed the patched tire and then brought the car down into my brother's building, which had recently undergone some work to energize the heated floor. Still without insulation the floor was only being heated to the mid 40 degree range but I found it amazing how much more comfortable it was in there on this first day of really chilly weather this season. I made relatively quick work of the clutch swap and showed my brother the problem unit. The fan clutch nut is supposed to be relatively difficult to spin at room temperature but the old unit's nut spun like a top while making various questionable noises, confirming the viscous fluid had long since leaked out or dried up, rendering the clutch worthless. As expected, once we fired up the engine the fan behaved much as it did when I replaced the clutch in my E36 -- it started blowing a LOT of air.


So what does this have to do with my own E46? Nothing beside the fact that I now know how to pull the shroud and mechanical fan. Helpful knowledge considering this procedure is necessary for most routine maintenance including belt replacement that I expect to do in the spring simply because the belts, along with every other part in the car, will be 10 years old in April.

Oh yea. That top rivet? The fixing pin broke in place as I tried to remove it so I had to chip away at it with a small chisel, breaking it up into enough pieces that the body could be carefully pulled out of the shroud mounting boss. I must admit to smirking a bit when it came time to install the new rivet.

A 32 cent gamble will beat an unplanned trip back to the dealer every time.

Total Mileage: 19680