Under chassis Engine Cover

I’m not sure if thats the exact name to call it, I just want to know if you guys are still using this which I’m planning to put it back to save my garage floor on the oil dripping which I see that this will help or Subaru did it in purpose. I’ve seen a lot of cars without this underneath. Anyways the felt absorbent paper came off cause of the age and do somebody knows the exact part numbers of it?

http://parts.subaru.com

I just bought one, from what I remember, the only difference is if it is 1 peice or 3 peice undercover. Yours looks like mine though. Looks like 2005 did not get a cover in the US.

56410AG15A this was my part number. Comes with the pads and sound absorption ~$80

My 05 has the 1 piece cover. Insulation isn’t needed, if your’s fell off just throw it away. The cover is there to protect the engine from stuff but also serves an aerodynamic purpose.

If your engine is leaking, all the undercover does is change where the oil drops fall on your driveway.

 

I toss them as they don't really protect the engine from anything (they're plastic, your engine is aluminum and steel), and they're always in the way when doing inspections or undercar service.

I toss them as they don't really protect the engine from anything (they're plastic, your engine is aluminum and steel), and they're always in the way when doing inspections or undercar service.

 

Also cause punctured oil filters are awesome, and heat shields and ground straps don't rust.

Far better to run the undertray. It aids in cooling of the engine as it directs air flow over the exhaust manifolds and even though it's plastic, it does help protect a lot of things under the engine compartment.

I've been struggling with this one for a while. I ran mine until about two years ago when I rebuilt the engine. I left it off for a couple weeks to verify there were no leaks...it's still off. My engine temps hover around 179, and only increase when the vehicle isn't moving quickly enough for aero cooling to impact it anyway. I slither past it every day getting into the wagon.

 

 

 

It's so floppy and I'd like one of the metal options, but can't bring myself to pay for it. I need to just order the pop-its and put the lasagna looking plastic back.

Also cause punctured oil filters are awesome, and heat shields and ground straps don't rust.

 

Not sure how many punctured oil filters you've suffered in your life but my count at age 42 is hovering at zero.

 

If you live in a salt state, your shit is gonna rust. No tupperware "shield" is gonna save you.

 

Not saying they don't serve a purpose, just that the benefit is not worth the hassle (to me).

Have to agree with lockmedic, they're not going to do much to prevent rust. They do an alright job of keeping dirt out of the engine bay though.

Not sure how many punctured oil filters you've suffered in your life but my count at age 42 is hovering at zero.

 

If you live in a salt state, your shit is gonna rust. No tupperware "shield" is gonna save you.

 

Not saying they don't serve a purpose, just that the benefit is not worth the hassle (to me).

 

But Tupperware keeps things fresh...............

Removing the cover is not advised if you live in a region with a lot of snow in the winter. Your suspension is going to jam up with snow every time you drive through a snow bank/ridge that is higher than one foot. Compacted snow and ice (like left behind by a plow) may cause damage. The cover pushes the snow out of the way and protects your front suspension, etc.

I ran over a deer in 2014, the smooth plastic shield helped the spin the deer and it only got splattered on my transmission and back. The plastic got destroyed and took a lot of zipties to fix (still holding in 2018!). Without the plastic pan I'm sure my oil pan and filter would have been full of guts and maybe even punctured.

 

Another added benefit is snow driving, my '12 2.5i Outback doesn't have a belly pan and the empty space between the header and radiator gets stuff with snow. While LGT is fine.

I live in Connecticut and took my undershield off a couple years back. Had an issue with a hole in my catalytic converter and when I replaced that, I never put the cover back on. The underside of my engine, exhaust, etc have all remained clean and rust free.

The undercover/splash tray serves multiple purposes. On a turbo tmic car it is an integral part of tmic and radiator cooling. You should ABSOLUTELY be using one unless you are running a fmic and the hood scoop is blocked off. Even then they are a beneficial part of the radiator cooling operation.

I've heard that argument (aids radiator cooling) multiple times and always counter with "if it's so essential, why didn't Subaru use them on ALL their cars?

 

Seriously. 3rd gen Outback got it but the 3rd gen Legacy just got little maxi pad wings on the sides (that do nothing to save those pesky oil filter punctures everyone's getting). Pretty sure it's the same on 4th gen. Turbo cars got them (yeah, I'll concede they may help with intercooler breathing but I'd love to see some objective data to make that point), Outbacks got them, but the lowly 2.5i cars did not (from what I can remember).

 

I really don't think they're that important. My beef with them is they're usually beat to shit and missing/replaced with incorrect fasteners and covered in oil and obscures my view of the plate on the crossmember which I use as a jack point when I wanna lift the whole front end up.

 

Maybe if you're driving through cornfields or a cooked pasta factory on your morning commute they'll keep some noodles off your engine but the "foreign object engine protection" benefit never held water with me.

They are not designed or intended to protect from impact. They are a "splash guard". They protect the headers from water. Hot headers crack fast when they contact cold water.

 

Otherwise, its simple air flow and physics. Air like water and electricity takes the path of least resistance. Trays are designed to create a low pressure area under the hood. A high pressure are will casue a drastic decrease in air flow.

 

Many teams have tested this repeatedly on track. Just as I have. I give you the info freely, what you do with it I cant control. I can lead a horse to water, but I can't make them drink.

I need to find some free time and do intercooler manometer pressure differential testing with and without the under tray. I did it earlier this year and saw a slight benefit with the tray off (I do have a front lip, that works like an air dam). Once I stop being lazy I'll do it again, heck might even remove the front lip too.

I've heard that argument (aids radiator cooling) multiple times and always counter with "if it's so essential, why didn't Subaru use them on ALL their cars?

 

Seriously. 3rd gen Outback got it but the 3rd gen Legacy just got little maxi pad wings on the sides (that do nothing to save those pesky oil filter punctures everyone's getting). Pretty sure it's the same on 4th gen. Turbo cars got them (yeah, I'll concede they may help with intercooler breathing but I'd love to see some objective data to make that point), Outbacks got them, but the lowly 2.5i cars did not (from what I can remember).

 

I really don't think they're that important. My beef with them is they're usually beat to shit and missing/replaced with incorrect fasteners and covered in oil and obscures my view of the plate on the crossmember which I use as a jack point when I wanna lift the whole front end up.

 

Maybe if you're driving through cornfields or a cooked pasta factory on your morning commute they'll keep some noodles off your engine but the "foreign object engine protection" benefit never held water with me.

Those examples don't have a functional hood scoop with a TMIC. I've seen data in the past on these very forums years ago showing the negative pressure differential behind the TMIC created by the engine splash guard that helps the hood scoop function well. FMIC or NA - not nearly as important (but does protect splashing, corn fields, noodle factories etc).

Actually here you go, found my spreadsheet:

 

It was a quick preliminary test, so I haven't made too much sense of it:

 

Inches Water Column (inH2O) at 40F ambient

 

Belly Pan, No Belly Pan

Before intercooler:

40mph Steady: 0.49, 0.62

60mph Steady: 1.01, 1.28

2nd Gear WOT Pull: 1.24, 1.54

 

After intercooler:

40mph Steady: 0.25, 0.16

60mph Steady: 0.47, 0.34

 

My quick thoughts:

After intercooler: I think lower pressure is better, which should mean there is more room available to be filled.

Before intercooler: I think higher pressure is better, which means more air is trying to enter the intercooler. But it could also mean that air is having a hard time getting through the intercooler thus creating more pressure before the intercooler.

FMIC and not blocking the scoop = BAD over heating issues on track. Still works better with a splash tray.

 

 

 

As basic as possible you dont want a "pillow" of high pressure air under the hood.

 

 

 

The negative pressure differential under the TMIC (which is greater with a splash tray) increases the high pressure air flow through the TMIC and out the bottom of the engine bay (flowing towards the rear of the car).

I stand corrected.

 

Still not running the damn thing.

Removing the cover is not advised if you live in a region with a lot of snow in the winter. Your suspension is going to jam up with snow every time you drive through a snow bank/ridge that is higher than one foot. Compacted snow and ice (like left behind by a plow) may cause damage. The cover pushes the snow out of the way and protects your front suspension, etc.

 

Richard where you located I’m in the West Island.

I stand corrected.

 

Still not running the damn thing.

 

Buffoon.

I left it off over the summer...cause I'm lazy