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Old 01-22-2011, 09:25 PM   #1
meeno
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Default plastic undercarriage...how necessary is it exactly?

as you can tell by the question, my undercarriage is broken; the bolts are rusted of, and the plastic couldn't handle the snow storms of the northeast.

so how necessary is it anyway? is it likely to harm my engine if i leave it off (at least until i can get to a junk yard and find one that isn't ridiculously overpriced)?

thanks
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Old 01-22-2011, 09:32 PM   #2
mzdahalos
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Default Re: plastic undercarriage...how necessary is it exactly?

kinda depends...I'm running a CAI so i leave the back half on to keep it protected...I can see how it kinda protects the exposed oil filter as well
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Old 01-24-2011, 11:10 AM   #3
URBANmanusa
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Default Re: plastic undercarriage...how necessary is it exactly?

Think about how beat up it looks ... now imagine what shape your engine might be in if it had to absorb all that. I've heard of some drivers cutting away some of it to make certain maintenance access easier.

I've had other older cars that did not have a shield, and the engine definitely suffered from more corrosion as a result. Clean is good. Pretty much all newer cars have them.

If you had to run without it for a month or so, probably you would not suffer too much damage. I remember seeing an aftermarket shield. You might want to google and see what you can find.
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Old 01-24-2011, 11:53 AM   #4
gejay99
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Default plastic undercarriage...how necessary is it exactly?

I had mine off for about 2.5 months cuz all of bolts fell off and it started dragging on the freeway. Long story short everyone is right. My car is only a year old and now the engine bay is hella dirty. It'll also affect the tape around your cables and will start to peel off. The shield also protects yours car from rocks getting inside to your motor and parts. Go to the dealer and ask for the part number and buy it new at www.onlinemazdaparts.com. They sell it to without the mark up of the dealer. I think it's only $50 for the middle plastic. I spent about $280 to replace everything from bolts to the fender lining etc. The dealer was asking $500 then labor.

Good luck.


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Old 01-24-2011, 01:08 PM   #5
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Default Re: plastic undercarriage...how necessary is it exactly?

"Rocks getting inside to your engine" Seriously?

I disagree with the above posters. I've had my car since early 2004 bought new. The shield was on till early 2009. Was my shield beat up? Uhm no, it was dirty of course, but it's not like it had scrapes and gouges on it. As with everyone else, the screws were all rusted and it became pretty much impossible to take it off without tons of aggravation and work. Rather than pay several hundred dollars for a replacement I decided to take it off and make my own judgment.

If you search these forums, you will see internet scholars who will tell you the horror stories of running without a shield. First I was told my mileage would suffer greatly and the car would be unstable at highway speeds, since the shield is for aerodynamic purposes. My car MPG is unchanged, as is my handling characteristics.
Second I was told rocks or other things on the road would harm my engine, or other parts underneath the car. I do all my own maintenance which has included belts, motor mounts, oil changes, etc all underneath the car. There is no such damage in 2 years.
Lastly, they'll tell you it helps with rust prevention, since salt won't enter the engine bay, which is again not accurate. In 08' with my shield being on 100%, plenty of my components have rusted over completely. Even with a shield, my engine in Chicago winters was always coated in salt. The metal brackets of my hoses are completely rusted over, again this is with the shield on all the time before 2009. If you live in a winter state and you think that shield is protecting against rust you are just flat wrong, coming from a 7-winter owner of this car. This particular car rusts, and badly. You can see the threads from the guy's in Canada who have rust eating through the car.

I run stock, so I don't worry about the water issue with my air filter. I've been through pretty bad rainstorms and checked the belts right after my trip. A possible concern of course is having water get on your belts while driving, since the belts go down near the bottom of the engine. I've never seen a drop of moisture on the belts with the shield off. If I ran a CAI I would certainly run with a shield, hydro-locking is always a concern with those.

So my opinion for Meeno or anyone else with this question, is to run it without and check YOUR results, not what someone on here TELLS YOU might happen or will happen. My MPG and handling are the same, I've experienced no damage to my engine compartment -- my shield when taken off had no damage at all, leading me to believe it's not saving me from great danger. Will having the shield off expose your engine to salt? Sure, but this shield is not going to be a cure-all. I have terrible rust after 4 winters with it on all the time.

The big benefit which I haven't mentioned is doing maintenance such as oil, coolant, power steering, etc right away without fighting with the shroud. I find it silly that it takes 20 minutes to change your oil, but (in my experiences) an hour to try to get the shroud off without stripping the bolts or breaking the plastic. I for one am very happy I decided to run without it, as it has been much easier to do my work on it and I have had no side effects to having it off.

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Old 01-24-2011, 01:31 PM   #6
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Default Re: plastic undercarriage...how necessary is it exactly?

http://www.mazda3forums.com/index.ph...407#msg3851407

This one from PartsGeek is affordable, and fit perfectly on my 2007.

Also, if you want to make it easier to remove and reattach, just get a jumbo pack of big black zipties. Then, when it's time to change your oil, just snip them with wire cutters in half a minute.
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Old 01-24-2011, 03:32 PM   #7
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Default Re: plastic undercarriage...how necessary is it exactly?

Mummyman, wow, that was a pretty major rant.

My experience, no doubt about it, less crap gets into your engine compartment as a result of the shield being in place. I say this comparing current experience to what was the case with my former 1990s car, which had a minimal shield. Is it perfect? No, some of whatever is on the road will get in. But it definitely helps.

I don't like to go down a path of removing or not replacing something a team of automotive engineers thought was a good idea to have. Not unless I'm really sure I fully understand why it was there in the first place. Especially given how cost conscious companies are, would they put it there if they didn't think it was necessary?

Sure, a car might run for years without a shield, and with some luck, nothing bad will happen. But then one day, part x, after being blasted by road crap for the 1000th day in a row, needs to be replaced. What I am saying is I look at it as kind of an insurance policy.
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Old 01-24-2011, 07:08 PM   #8
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Default Re: plastic undercarriage...how necessary is it exactly?

Well I wouldn't consider my post a rant, merely my personal experiences.

Second, there is no proof at all that "road crap" is being blasted on my engine, as you suggest, which may one day in the future cause me an issue. I've never read of anyone who doesn't use a shroud having this issue, and I never have. I am pretty meticulous about taking care of my car, and check it out top to bottom every time the oil or other service is due. My engine has not, nor any other parts, sustained any damage even in the slightest.

If you believe you should use the shroud because it came with the car by all means. If it makes you feel as you have an extra layer of protection, then you should use it for your own piece of mind. I disagree, based on my personal experience, but I certainly understand why someone choose to stick with it.

What I will disagree in directly with you, and with some others from different threads, is assuming you know the ramifications of NOT running a shroud. This is your assumption that "road crap" is going to be pelting my engine parts everyday I use my car. That is just flat out false, there is no evidence having the shroud removed will cause this. There are quite a few people who, like me, just got rid of the shroud. I have not seen one thread of an issue pop up due to the choice to remove it.

Just like a different user who swore on a thread anyone who dared take off the shroud will kill gas mileage and hurt the high speed characteristics of the car. This is just flat-out nonsense, and I keep the MPG logs to prove it.

I'm all for people doing whatever they feel is best for their car. Insurance policy, as you said. What I'm not all for is people making claims that my engine is going to be pelted with rocks everyday (even though the wheel well protection is fully intact), or they know my MPG will fall and handling will suffer. These claims are just flat out wrong.

If you have any evidence that running without a shroud will cause issues, then I'd love to look at it. I guess it just bothers me when people who have never even driven with the shroud off, can tell me the ill-effects being done to my car. Be it MPG or handling, or "road crap" blasting my engine parts. How could you possibly know that is the case, or are you just assuming you know it to be true?
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Old 01-24-2011, 08:11 PM   #9
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Default Re: plastic undercarriage...how necessary is it exactly?

Mine had a good sized hole in it near the A/C compressor and basically ruined my a/c drive belt and shortened the life of my serpentine belt as well. Water/dirt/etc. got on it continuously.
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Old 01-24-2011, 08:38 PM   #10
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Default Re: plastic undercarriage...how necessary is it exactly?

[quote author=Mummyman link=topic=185225.msg3915097#msg3915097 date=1295914123]

What I will disagree in directly with you, and with some others from different threads, is assuming you know the ramifications of NOT running a shroud. This is your assumption that "road crap" is going to be pelting my engine parts everyday I use my car. That is just flat out false, there is no evidence having the shroud removed will cause this. There are quite a few people who, like me, just got rid of the shroud. I have not seen one thread of an issue pop up due to the choice to remove it.

I'm all for people doing whatever they feel is best for their car. Insurance policy, as you said. What I'm not all for is people making claims that my engine is going to be pelted with rocks everyday (even though the wheel well protection is fully intact), or they know my MPG will fall and handling will suffer. These claims are just flat out wrong.
[/quote]

My "evidence" is how clean my engine compartment stays, versus my previous vehicle which did not have a full bottom shield. Over time, general principle, dirt is bad for anything mechanical. Vague, yes, but I buy into it.

Sure, I guess your cynicism is the same as mine toward owners who spend $6-plus per quart for some super fantastic fully synth motor oil - no evidence its really any better than oil which costs less than 1/2 the price.

I'll stand by my previous statement that the Mazda engineers decided it was worth it to have a shield. If your having no probs 2 years without it, thats good. I don't wish bad on you.
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