I can just ignore this, right?
February 14, 2011 7:46 AM   Subscribe

How important is the big piece of plastic that goes across the bottom of the front of my car, under the engine? Because mine fell off.
posted by smackfu to Travel & Transportation (22 answers total) 1 user marked this as a favorite
 
I think that's the engine splash shield. I wouldn't drive through any puddles if I were you.
posted by Cat Pie Hurts at 7:50 AM on February 14, 2011


It's kinda important. It helps smooth the flow of air under the car. You may experience a slight decrease in gas mileage without it. The car may be a bit noisier at highway speeds.
posted by Old Geezer at 7:51 AM on February 14, 2011


Gravel guard more than a splash shield. You don't want rocks getting thrown up into your serpentine belt, fan, or other moving parts. Replace it.
posted by The Deej at 7:56 AM on February 14, 2011


It's important. It covers the oil pan and if that gets punctured while you're driving, well, that's not good. It protects the undercarriage (and engine compartment) from road debris and from scrapes you get if a curb is too high or if you go too fast over a speed bump. If I were you I'd get it fixed (and as a matter of fact, I was you a couple years ago when the cover on my Passat broke).
posted by cooker girl at 7:57 AM on February 14, 2011


It is mainly for smoothing airflow under the car for aerodynamic drag reduction. It is not a splash shield.

As such, it really isn't that important other than for fuel consumption means. Yes, your car would be better off with it (it does provide a minimal level of protection to wiring and hoses in the engine bay) but it isn't any sort of drama. Cars didn't have those for years and as long as nothing was being held up by it (ie nothing is dangling down now that is rubber or wire and looks delicate) it will do zero harm to your car to drive without it. Don't worry about it - replace it or don't is entirely up to you.
posted by Brockles at 8:00 AM on February 14, 2011 [3 favorites]


It's important. It covers the oil pan and if that gets punctured while you're driving, well, that's not good. It protects the undercarriage (and engine compartment) from road debris and from scrapes you get if a curb is too high or if you go too fast over a speed bump.

This is not true. It's a weedy piece of plastic. It will do next to nothing in terms of protecting your oil pan, undercarriage or any other major component on the car. Anything that would damage, for example, your oil pan will not be stopped by a relatively thin piece of plastic.
posted by Brockles at 8:02 AM on February 14, 2011 [4 favorites]


I had that plastic shield thing fall off of my old VW Golf and I never bothered putting it back on. It didn't seem to make a difference and I had the car a good three years after it happened -- in New England weather, no less.
posted by chowflap at 8:09 AM on February 14, 2011 [1 favorite]


Perhaps we're talking different pieces of plastic? Mine was actually really thick and substantial and quite heavy (I had to lift it myself when it came off in the driveway). I'm just going by what my mechanic friend told me, so if I'm wrong, so be it!
posted by cooker girl at 8:11 AM on February 14, 2011



This is not true. It's a weedy piece of plastic. It will do next to nothing in terms of protecting your oil pan, undercarriage or any other major component on the car. Anything that would damage, for example, your oil pan will not be stopped by a relatively thin piece of plastic.


Pretty much.
Mind you, I've never owned a vehicle new enough to have one. Maybe the quality of steel is getting lower. ;)

It is mainly for smoothing airflow under the car for aerodynamic drag reduction. It is not a splash shield.


This is more the case, if you're talking about what I think you're talking about.
posted by Stagger Lee at 8:13 AM on February 14, 2011


There is a difference between your piece of plastic, and what cookergirl is referring to, which is a 'skid plate,' as seen here: http://www.rallyarmor.com/store/subaru-impreza-wrx-sti-skid-plate-p-148.html

If it's just a <3 mm plastic guard, it's not going to protect against curbs, rocks or the like. Considering it just fell off (I'm assuming no curb-car intersection or the like), it's not going to be harmful if you take it off.
posted by kurosawa's pal at 8:17 AM on February 14, 2011 [1 favorite]


Under car airflow and noise are the main reasons. But depending on the car, it can be a very vital component for the cooling system, ducting air across the radiator rather than under/around it. Many a hot-climate Miata will tell you why you want it.

Keeping spashy water out of the engine bay is good for metal bits and electrical bits in the long term, too. It's a lot more pleasant working on a car that isn't filthy in there. I always use it in the winter, even if it's a PITA getting it on and off for oil changes and whatnot.
posted by pjaust at 8:17 AM on February 14, 2011


My car (a Toyota) had one of these flimsy little plastic shields. It eventually came off and I never bothered replacing it. It has since been in and out of the dealership for regular maintenance and no one has ever said anything.
posted by jquinby at 8:22 AM on February 14, 2011


The passenger half of mine disappeared a while back, haven't noticed any difference (except during the oil change, reaching the drain bolt's now a lot easier). My mechanic hasn't mentioned it and my little Toyota turns 20 in April.
posted by Rash at 8:31 AM on February 14, 2011


Thanks all. If it helps, here is a photo, which is labeled as part BP4K-56-111.
posted by smackfu at 8:43 AM on February 14, 2011


It is usually the clips that hold it on that fail - any auto place will have replacements for them for a few dollars. Depending on which car company it is called a lower deflector, lower schroud, or undercover, and everybody has been mostly right - on some cars it is part of reducing the under car drag and moving air around but generally its main purpose is to prevents water (puddles) from splashing up into your belts, which will then squeal like crazy.

It isn't crucial, which is why it is just fastened on cheaply and made out of plastic. If the car starts squealing or overheating though - you'll likely want to consider replacing it, otherwise think of it as going commando.
posted by zenon at 9:29 AM on February 14, 2011


Speed bumps damaged mine on my 1999 Civic and my mechanic said what Brockles said and cheerfully removed it. No difference since.
posted by dmt at 10:12 AM on February 14, 2011


What kind of car is it? On my Passat, the deflector is the only thing holding the wheel wells in place. Without the deflector, driving at highway speeds causes the wind to push the front side of the wheel wells into the tires ... which eats up the wheel wells ... in a few months you'll need new wheel wells. Also, your engine gets way dirtier without the deflector. They're expensive on VWs ($250!) but you need it IMHO.

I had my indy VW mechanic install a new deflector and cut access ports for the oil drain plug and oil filter with a hole saw. Now the Jiffy Lube people don't need to break or lose the deflector at each oil change interval. Works great.
posted by dudeman at 10:39 AM on February 14, 2011 [1 favorite]


Volkswagen by any chance?

Not important.
posted by radioamy at 11:01 AM on February 14, 2011


It also makes the underneath look pretty. My passat's fell off and the dealer fixed it under warranty. It's not super important but it's probably easy and cheap to fix.
posted by jeffamaphone at 11:07 AM on February 14, 2011


They do help to deflect rocks and crap from getting up into the radiator fans, belts and other moving parts at the front of the engine. And, as others have mentioned, a lot the flat shields hook onto the wheel well liners and create a solid(ish) unit.
posted by Thorzdad at 11:59 AM on February 14, 2011


HA! I recognize the back of the car and that plastic piece. Mazda3, huh? Mine came off too. It's been off for a year, never had a problem.
posted by sephira at 5:22 PM on February 14, 2011


They're for aerodynamics. Cars didn't used to have them at all. Ignore it.
posted by chairface at 7:45 PM on February 14, 2011


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