Engine undertray "diaper"-> thoughts?

5718 Views 14 Replies 9 Participants Last post by bleakSTI, Aug 29, 2013

Guardian-X-

Discussion Starter · Aug 27, 2013 (Edited)

Hi guys,

After thinking about for like 20 times each time i pulled the tray to do an oil change and whatnot i decided to throw out the undertray "diaper". Now i don't exactly know what this thing is for but here's what comes to mind.

-Oil,coolant diaper so these fluids don't spill on the road.
-Heatshield for undertray

Now the reason i tossed it: This thing was always soaking wet,heavy and dirty and it caused rust all over the lower braces of the car. Even on dry periods this thing didn't dry for sh*t so kept the underside damp all the time. I also sanded and painted the edge's of the large brace surrounding the engine (name?) a year back and the thing started rusting again so i was sick of it being wet all the time under the car. My car is a DD so it's seeing alot of rainy day's,snow,dirt you name it.

Advantages in my opinion?

-Undertray won't be keeping the underside damp all of the time (unless during/after rainy wether ofcourse) so less rust.
-Easier to spot leaks should these occur.
-less weight (okay not much but this thing was heavy when wet)

Now the pics:

Filthy,damp diaper removed

"Diaper" itself (never had a leak so hasn't seen more than a few drops of oil/coolant)

The rust that keeps coming back due to wet underside all the time

All cleaned up and back to go under the car (note: i kept the 2 small diaper pieces on top) the "diaper" itself starts to disintegrate almost instantly upon handling it.

Now all that is done what are your thought on this? Do you think you should keep it for some reason or also agree on tossing it after a number of years? Share your thoughts!

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RecceRS

· #2 · Aug 27, 2013

I was unaware that newer models had those "diapers" since my 04 has only the plastic undertray. Anyhow, besides offering slightly better aero, protection from bouncing rocks and water splashes on your hot headers, the tray does not do much else. Any leak, even small, will end up dripping on the ground anyway. That's what mine does...

The front subframe is prone to rust on the GD, I've seen a lot totally rusted through in only a few years (bad winters here though). My advice would be for you to rustproof it. You can do this cheaply by keeping your used oil from your last oil change and spraying it on (including inside the various holes if you can manage). As for me, my various past oil leaks and blown turbo has done the job for me over the years... my subframe and engine crossmember are all greased up!

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got2boostit2

· #3 · Aug 27, 2013 (Edited)

I've never seen that diaper on USDM STi's must be a Euro spec addition.

Deuce Cam

· #4 · Aug 27, 2013

It also aids cooling by allowing the radiator to work better due to the aerodynamic changes.

SubieEngineer

· #5 · Aug 27, 2013

Got2Boostit2 said:
I've never seen that on USDM STi's must be a Euro spec addition.

Agreed. My 07 certainly never had it. I see no negatives by leaving it off the car.

0392

· #6 · Aug 27, 2013

I have a three month old 13 hatch. Since I'm new to this Subi thing here's what I known from the Porsche sector. Early 90s 911 had a under tray world wide. After several years, the US market 911 started experiencing premature valve guide wear...if your an owner, at 25-35k I'm sure your not going to be a happy camper. Later it was discovered that Porsche installed this especially for the Swiss mkt as they have x noise requirements....YA Porsche F up as this caused many 911 to have valve jobs unnecessarily. My take as mentioned above I that mfg used this for aero improvement on gas mileage and oh ya to contain any leaks from soiling some ones garage. I'm going to ask the Tech to leave this off once my car reach the first oil change.

got2boostit2

· #7 · Aug 28, 2013

Deuce Cam said:
It also aids cooling by allowing the radiator to work better due to the aerodynamic changes.

LoL, wut? The diaper?

Deuce Cam

· #8 · Aug 28, 2013

:rofl: I skimmed the op too quickly and didn't see the foam thing. I thought he was talking about the whole undertray.

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got2boostit2

· #9 · Aug 28, 2013

LOL ^^^, thought so.

Kaimino

· #10 · Aug 28, 2013

Hmm first I've seen this diaper as well. Well, less front end weight :lol:

Reactions: 1

Guardian-X-

Discussion Starter · #11 · Aug 28, 2013 (Edited)

Well it looks like there isn't much of a reason to keep it on. Glad i tossed it

(still have it arround but it's a bit like cardboard/hard foam like stuff and it cracks and crumbles once you pick it up or set it down in the wrong way. I never would have thought this to be a euro-spec only type of deal either ... still learning stuff everyday

@recceRS: Hmm sounds tempting but that would become a filthy muck quite fast? Not that it would hurt anything though ... is was baffled that my layer of hammerite paint started to rust again

maybe because i sanded and degreased the area instead of the "paint ontop of rust!" like the can says lol

Btw it looks like i forgot a pic with the diaper in place but i managed to find one from a few weeks earlier

so here it is (i'll also put it up in post 1)

Thank you all for the comments and info!

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Nigel

· #12 · Aug 28, 2013

All the Canadian GD's Ive seen also have a diaper so it might be a cold climate thing? lol Not sure why...

got2boostit2

· #13 · Aug 28, 2013

Guardian-X- said:
Well it looks like there isn't much of a reason to keep it on. Glad i tossed it (still have it arround but it's a bit like cardboard/hard foam like stuff and it cracks and crumbles once you pick it up or set it down in the wrong way. I never would have thought this to be a euro-spec only type of deal either ... still learning stuff everyday

@recceRS: Hmm sounds tempting but that would become a filthy muck quite fast? Not that it would hurt anything though ... is was baffled that my layer of hammerite paint started to rust again maybe because i sanded and degreased the area instead of the "paint ontop of rust!" like the can says lol

Btw it looks like i forgot a pic with the diaper in place but i managed to find one from a few weeks earlier so here it is (i'll also put it up in post 1)

Image Link

Thank you all for the comments and info!

Baffling or reducing engine noise? Interesting.

RecceRS

· #14 · Aug 28, 2013

Nigel said:
All the Canadian GD's Ive seen also have a diaper so it might be a cold climate thing? lol Not sure why...

Really ? I don't remember mine having it but then again I might have removed it so long ago that I do not have any recollection of it... which is more than likely!

bleakSTI

· #15 · Aug 29, 2013

on the fords i see everyday the computer describes this "diaper" material as sound dampener.

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