E36 engine fan noise

[Chris]

This is for all the BMW haters out there... something I've noticed from my 2 E36 328i/is. When I'm in a lot of traffic, or short stop and go situations, the sound of the engine changes drastically. The fan noise is extremely loud; sounds like an old truck or a Jeep Cherokee. It also feels more sluggish. After speed picks up for a while, it goes away. Can I expect this all summer in the heat, and when I'm in traffic? What's the cause?

[SlimKlim]

I think its just the draw from the mechanical fan, and yes, expect it all summer. Some people convert to electric fans, but personally it's never really bothered me that much.

[D_Eclipse9916]

hmm never had that. Did you check resistance on the fan? It may be starting to come apart giving a harsher vibration, in which case youd want to replace it immediately. However its both your cars so I dont know. I switched to an electric fan immediately because higher rpms constantly on track would be more likely to destroy a stock fan anyway.

[SlimKlim]

hmm never had that. Did you check resistance on the fan? It may be starting to come apart giving a harsher vibration, in which case youd want to replace it immediately. However its both your cars so I dont know. I switched to an electric fan immediately because higher rpms constantly on track would be more likely to destroy a stock fan anyway.

I do notice the noise when my mechanical fan switches on but I haven't really noticed a loss in power. I've seen what they look like when they grenade and its not pretty though. I'll probably switch mine over this summer when I do a whole pile of preventative stuff.

[PDenbigh]

If it's a mechanical/clutch type fan, it's normal. The viscious fluid gets hot in traffic, so it grabs the fan and makes it spin fast (thus cooling things better). My F150 does that after pulling a long hill and then coming to a stop.

If it's electrical, I don't have a good explanation.

Peter

[Jake]

The E34 does this too, and I've noticed it on other BMWs. Kind of a higher-ish pitched "whooo" noise that changes with RPM? Mine only does it on warmer days I think. I've written it off as normal, for now. The cooling system (including fan clutch) was just re-done before I bought the car, so I think it's just an odd quirk. Not tracking this beast so I see no need to upgrade to electrical.

[BLINGMW]

You young punks and your fancy fan clutches and electric fans. Back in my day they just bolted the fan straight to the water pump pulley so if you DON'T hear that wooshing sound and aren't always down on power, then something's wrong!

[D_Eclipse9916]

You young punks and your fancy fan clutches and electric fans. Back in my day they just bolted the fan straight to the water pump pulley so if you DON'T hear that wooshing sound and aren't always down on power, then something's wrong!

"Get off my lawn!"

[Chris]

cool thanks for the info. I assumed it was normal, especially since the new one has such low miles.

On another note, I haven't spent much time researching the known issues with the rear shock mounts on these cars, so maybe someone can provide some insight? Is it common maintenance (or preventative maintenance) to upgrade the rear shock mounts to a later E46 or whatever mount? What can happen over time; can the shocks break through the metal where they are mounted? If I were to pull my shocks down to install new mounts, this will affect the alignment, correct? I did this on my e30 track car, but I assumed it would help only because of the demands of track driving.

Also... it looks like someone in the past may have dropped off the road on the right side of my car. There are some stratches underneath and the RR tire looks to have rubbed the inner fender some. This wheel well also seems to be lower than the other side (I can fit a finger between the tire and the fender on one side, and not the other). I'll look at the shock for signs of leaking next time I'm working on the car, but it tracks straight and doesn't feel bad when I push down on this side of the car. Anything to be concerned about?

(sorry for rambling on, thanks for the input)

[D_Eclipse9916]

E36s have weak front and rear shock towers. The OEM fix for the front is cheap, but requires removal of the shock. The rear is aftermarket and is available from a few places for 20-35 bucks. It will simply require pulling back the carpet and undoing the two 13mm nuts on the top of the shock and slipping the reinforcement on. Tighten those nuts back on and your good. No worries about alignment or even getting the car in the air.

[Sully]

The OEM fix for the front is cheap, but requires removal of the shock.

Whats the OEM fix?

[D_Eclipse9916]

Dont remember the part number off handbut just ask turner motorsports and theyll be able to get em for you, they are only like 20 bucks a side.

[Chris]

so what can happen if the shocks are not reinforced? Is this failure common on street cars?

[BLINGMW]

you're talking about the rear shock tower metal actually failing? Not a concern IMHO.
I can only imagine this happens:
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when you let the shock mount get loose, bang around for months and shred the surrounding metal. Or if the shock mount got really rusted out due to years of busted trunk seals and neglect. There's a gasket that probably traps water between the mount and tower as it ages if it's getting wet regularly. I fail to see how something like this:

just bolted the same way the mount bolts in is going to help much unless you actually weld that thing to the tower. I'd skip this "upgrade" unless someone can explain to me how that helps.

It's the shock mount itself that's a sucky design and commonly fails.

It's been doing that ever since they came up with the 3 series. The bushing blows out and the top of the shock shaft bangs around in the mount. No big deal, but they're cheap to replace before it happens. Bimmerworld and others have some cheap, better designed, urethane versions that don't add any NVH, I consider it a must if upgrading to a sport suspension as that's going to accelerate the bushing failure. E46 is stiffer, but still rubber. For just a street car on tired suspension, I'd wait 'till it fails or looks like the one above. And you won't need the front strut mount reinforcements either without a really aggressive suspension. I'd get a strut tower bar to help share the load up there before I'd get the reinforcement plates. Looking at the price of the plates though, for $10-15, well I guess that's cheap insurance.

[D_Eclipse9916]

Those reinforcement plates help spread the load just as a washer would. Stock car? Probably not, Stiffer suspension? 10-15 bucks is well worth a possible 200-300 repair job.

[Chris]

cool thanks for the info guys.