W124 Underbody Sound Shields and Engine Cooling - PeachParts Mercedes-Benz Forum

Oldwolf · #1 06-03-2009, 01:32 PM

The underbody sound shields on the W124 seal the engine compartment pretty tight it looks like to me.

So I am wondering about the airflow through the radiator and where it is exhausted?

Would the engine run cooler (better air flow through the radiator) with the rear sound shield removed (the one under the transmission)?

Trade off would be more noise though.

scottmcphee · #2 06-03-2009, 02:33 PM

Air flowing through the rad hits the engine and is deflected pretty much everywhere around it. The bottom cover panel has an opening there at the bottom, lots gushes out there.

And amazingly, I found this little set of louvers on my 1987 300D on the driver's side between the engine bay and front wheel. Under some conditions, I'm not sure what, that louver opens up. Allowing more airflow. It looks like it might be temperature driven, or maybe just wind driven.

But, leave those covers on the car. It helps so much keeping water and road splash out of the engine, it keeps the rust down, and corrosion down on the outside of power train parts.

Your car has been going how many years with these on, just fine? Leave 'em on. If car is getting hot, fix the problem don't cover it up by 'uncovering' it.

Oldwolf · #3 06-03-2009, 02:52 PM

My engine isn't running hot...I was just thinking about air flow when I was under there removing the panels for an oil change.

You are right about how the panel keep the corrosion down, the under parts (for lack of a better phrase) were pretty clean actually. But the side of the panel facing the engine compartment was a mess. The insulation had long decayed away so I took my power washer and the inside surface cleaned right up.

I wonder if the factory applied insulation helps much with noise and if it would be worthwhile to reapply some?

I'll look around for the air louver you mentioned.

ds190 · #4 06-03-2009, 03:02 PM

Temperature change affects a spring element which opens those side louvers.

scottmcphee · #5 06-03-2009, 10:07 PM

Now how many cars do you know have temperature activated engine cooling louvers? MB you really had fun making these cars!

Jeremy5848 · #6 06-04-2009, 01:16 AM

Quote:

Originally Posted by scottmcphee

Now how many cars do you know have temperature activated engine cooling louvers? MB you really had fun making these cars!

And they actually work!. On hot days in traffic, my outside temperature gauge (the old style mounted on the left side of the bumper) goes crazy when those vents open and the hot air hits the sensor. No wonder Mercedes moved the sensor up front. You can test the mechanism that opens the louvers with a hair dryer. Mine was pretty stiff with age and dirt and rust but I cleaned it up and it works now.

Here is the coil that expands with heat to open the louvers (left side of engine bay near the ABS pump but down lower)

Here are the louvers closed (taken with the left front wheel removed)

Now the louvers are open

Jeremy

awsrock · #7 06-04-2009, 08:44 AM

I bought a used front panel for my car recently, and I find that it actually runs a bit cooler with it on. I know you weren't worried about the temp, but just sayin'

I'd love to find one for the transmission too, but..well, I haven't been looking for one.

As for sound, some could argue that it doesn't do much, but I think it helps keep idle noises down just a little bit, and it seems to help a bit more with wind / road noise on the highway.