My E420's splash shield fell off when I was driving slowly (5mph) into
a deep rain puddle in roadway and I realized it was getting too deep,
I stopped and slowly backed out and later notice my splash shield was
missing. Other than the obvious reason to use the splash shield, by
not using splash shield am I effecting the engine's performance due to
heat loss in engine compartment? What other effects of not having
shield may there be?
Much more noise. Less electrical reliability (more humidity enters and
increases oxidation of contacts, with the so called.... xmas-tree effect
on warning lights...). More potential rust on all metal sheet details.
So, I'd say, in general less reliability.
I'm not sure about heat loss and related problems you mention. Most
probably the gas consumption will be slightly increased. Especially at
high speed due to turbulence and less efficient aerodynamics.
It won't cost so much.... eventually try to find one at the scrapeyard...
You're not affecting the performance due to heat loss. There's loads
of excess heat, which is why cars have radiators. There could be some
small effect on drag, but at avg driving speeds, I doubt it amounts to
I thought the main radiator fan clutch has a heat sensor that engages
fan clutch when ambient engine compartment heats up, spinning fan
faster? Mine doesn't seem to spin faster even when engine temp peaks
to top white bar???
A thermal fan clutch runs the fan at lower speeds when the air moving
from the RADIATOR to the fan is cooler and increases the speed with
increasing air temp. It's there to save some small amount of energy
by not running the fan at a higher speed than necessary. That isn't
going to be affected much, if at all, by whether you have a spash
shield on the bottom of the vehicle or not. The main thing regulating
the engine temp is the thermostat, which controls the water flow
through the radiator. There is a huge amount of excess heat being
generated by the engine. No small change due to not having a splash
shield can cause a heat loss making the engine less efficient due to a
I'm not sure you'd be able to tell the difference without actually
measuring it. The speed varies by maybe 2X.
I'd just stop worrying about it and when you have time, go to a
salvage yard or online to find a replacement.
On Feb 20, 2:01 pm, email@example.com wrote:
I had the splash guard off my C270cdi for a while, and I thought the
car ran a lot cooler - approx 40c indicated at sustained highway
speeds, and it was noticable that the interior heater didn't seem as
warm as normal. It normally runs above 80C in city traffic. It
definitely affects noise too - note the absorbent materials on the
engine side. If it is dirty, I would degrease and steam-clean it
before re-fitting, and also steam-clean the front underside of the
engine and cross-member area to keep things nice and tidy.
That does not sound right. A working cooling system, even at its most
basic configuration (radiator, thermostat, pressurized, flowing air),
should be able to easily keep the engine temperature around 85C, plus or
The fan helps at lower speed. Fan affects very little when vehicle
speed is faster than 30 mph. The fan draws air through the radiator.
It is not used to send air to engine to cool. More or less air flowing
through the engine bay has no effect to a modern day water-cooled engine.
John (Ireland) wrote:
Thanks for the above. I was beginning to think I was alone here. If
a car is running at 40C on the highway, it for sure isn't due to the
presence or absence of a spash shield on the bottom of the engine.
I'd be looking at a missing thermostat.
No panic. I'd replace it in a reasonable time to prevent water getting
into unwanted places. There will be a minor effect on drag and hence a
very minor decrease in mileage (probably unmeasurable by you). Little to
no effect on cooling.
EJ in NJ
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