[Eddiee07]

As the title states is the engine undertray completely necessary? Ran over something a couple months back and it broke the holes where the tray is connected to the front bumper. Now it’s pretty much dragging everywhere I go. I do want to purchase a new one but is it fine if I drive the car for a couple of weeks without it? TIA

[tcphoto]

The under tray protects the belts and engine components from road debris and aerodynamics to a degree. Look up what happens when the drive belt shreds and gets sucked into the crankshaft. I would not drive it very long with it sagging or missing.

[mpathic]

Originally Posted by Eddiee07

As the title states is the engine undertray completely necessary? Ran over something a couple months back and it broke the holes where the tray is connected to the front bumper. Now it’s pretty much dragging everywhere I go. I do want to purchase a new one but is it fine if I drive the car for a couple of weeks without it? TIA

Be off with it, better cooling, 5+ needless pounds, waste of plastic, guaranteed to crack apart again.

[SnowGlobe]

Cooling will definitely be worse without the tray.
When the tray is in place there is a zone of high pressure ahead of the radiator (air rushing in when at speed from grill) which passes through the radiator to a zone of low pressure (engine bay)
When the tray is removed pressure underneath the car will "leak" above it, past the radiator causing turbulence + a pressure increase. This reduces the airflow through the radiator itself from the grill. I'd keep the tray or replace it.

Will you notice the difference? Debatable.
Will it have some effect? Definitely.

[nsjames]

Originally Posted by mpathic

Be off with it, better cooling, 5+ needless pounds, waste of plastic, guaranteed to crack apart again.

except there's a big piece of plastic bolted to it that seals the radiator to the bumper opening.

so no, not better cooling.

I drove without for a few days until I got mine cleaned up and didn't notice any difference.

but it's winter time, and I didn't drive in any wet weather.

[ckanderson]

Originally Posted by mpathic

Be off with it, better cooling, 5+ needless pounds, waste of plastic, guaranteed to crack apart again.

Yea, you couldn't be more wrong. Please think before posting

[Bali]

You’ll be fine in SoCal for a short time, since the temps are moderate, the roads pretty good, and the weather is nice. I’d probably try to stay on nice clean roads and avoid rain, but that’s me.

[Efthreeoh]

Originally Posted by tcphoto

The under tray protects the belts and engine components from road debris and aerodynamics to a degree. Look up what happens when the drive belt shreds and gets sucked into the crankshaft. I would not drive it very long with it sagging or missing.

LOL. Do you guys just make this stuff up on purpose just to start internet myth? Have you even been under the front end of an E90?

If any road debris were able to damage the serpentine belt and make it slip off the pulleys AND be ingested into the crank seal, the damage would not be limited to just the belt. The debris would take out the belly pan (if it was attached), the secondary plastic shield, the heater hose cross pipe, the bottom of the radiator, the lower coolant hose, thermostat, water pump, just to name a few things off hand.

Literally hundreds of million of cars for decades upon decades have been driving around for billions of miles without an under engine shield. BMW added the shield primarily for aerodynamics, and it secondarily keeps noise and dirt at bay.

Please stop doing this. Just for reference, this is what it looks like under the belly pan. You can't even see the harmonic balancer (it's protected by the front subframe cross member):

[Efthreeoh]

Originally Posted by SnowGlobe

Cooling will definitely be worse without the tray.
When the tray is in place there is a zone of high pressure ahead of the radiator (air rushing in when at speed from grill) which passes through the radiator to a zone of low pressure (engine bay)
When the tray is removed pressure underneath the car will "leak" above it, past the radiator causing turbulence + a pressure increase. This reduces the airflow through the radiator itself from the grill. I'd keep the tray or replace it.

Will you notice the difference? Debatable.
Will it have some effect? Definitely.

Again. LOL

[dleccord]

the internet never fails to deliver misinformation

OP ive been driving around w/o belly pan for a little over a year, rain or shine. engine bay is dirtier but don't lose sleep.

[Efthreeoh]

OP, you can drive without the under engine shield without worry about stupid shit like the serp belt being run off the pulleys or the engine over heating because of the loss of pressure build up in front of, or behind, the radiator (remember the car IS capable of mach 2.3 speeds) LOL.

What the real issue is the under panels for the rest of the car are susceptible to catching the air rushing underneath the car. Mainly the cover that is under the transmission is most susceptible to catching air. Below are a few pics I have of what it looks like underneath with the belly pan present and removed. If the belly pan is not catching air its self then order a new part (BMW is now charging out the ass for them) and leave it in place. If it is that broken up then I'd remove the remains of it AND the transmission cover. If you remove the trans cover, then re-install the screws that secure the drivers side panel so it is held tight to the chassis.

[Efthreeoh]

Just to beat this with a dead horse, here's a third pic with the belly pan and trans cover removed. There is a 3rd small cover, aft of the trans cover that could be removed as well (marked by the arrow). It's held pretty sturdily to the chassis however.

[tcphoto]

Efthreeoh, I don't think my comment is misinformation but I do think that your response is a bit over the top.

[CTinline-six]

Originally Posted by Efthreeoh

LOL. Do you guys just make this stuff up on purpose just to start internet myth? Have you even been under the front end of an E90?

If any road debris were able to damage the serpentine belt and make it slip off the pulleys AND be ingested into the crank seal, the damage would not be limited to just the belt. The debris would take out the belly pan (if it was attached), the secondary plastic shield, the heater hose cross pipe, the bottom of the radiator, the lower coolant hose, thermostat, water pump, just to name a few things off hand.

Literally hundreds of million of cars for decades upon decades have been driving around for billions of miles without an under engine shield. BMW added the shield primarily for aerodynamics, and it secondarily keeps noise and dirt at bay.

Please stop doing this. Just for reference, this is what it looks like under the belly pan. You can't even see the harmonic balancer (it's protected by the front subframe cross member):

Does your car have a steel oil pan, or did you just paint it black? Looks different than both of mine.

[colorado.e9x]

I've been driving without mine for a months and everything has been fine so far. I have a mild oil leak (from what I believe is the head gasket) and would prefer to see the consistency of the leak over oil sloshing around on the cover.

[OTO335i]

Originally Posted by tcphoto

Efthreeoh, I don't think my comment is misinformation but I do think that your response is a bit over the top.

Your comment is definitely misinformation... There's no way the belly pan only protects the belts from road debris which would cause them to shred, that's just ridiculous. The belt is prone to shred because oil leaks onto it from the OFH and then weakens the belt over time.

Like Efthreeoh said, cars have been driving around for years and years without belly pans and there were never any issues. It's basically easy money for stealerships and shops to make coin on to show some retard that their plastic belly pan has a crack in it and it will dramatically affect the vehicles components so they better change it asap!!

[Efthreeoh]

Originally Posted by CTinline-six

Does your car have a steel oil pan, or did you just paint it black? Looks different than both of mine.

The manual transmission version of the N52 has a steel oil pan. Automatics have an aluminum pan.

[Efthreeoh]

Originally Posted by tcphoto

Efthreeoh, I don't think my comment is misinformation but I do think that your response is a bit over the top.

Come man, it's virtually impossible for some type of road debris to hit the belt and have it ride off the crank pulley. It'd be a 1 in a 10 million shot. The crankshaft pulley sits right above the front cross member of the subframe and sits less than 4 inches from the fan shroud. Like I said, BMW added the belly pan for aerodynamics and noise abatement. If it was meant to guard from road debris they's have fabbed it out of aluminum or sheet steel.

The problem I have is people just make up shit on the internet and then the next thing, it's gospel. Just like the paint marks on the oil filter cap. Some knucklehead said the marks are alignment marks to make sure the cap is tight, when all they are is a quality check during production of the engine. If you look at a new car, there are numerous nuts and bolts that have such paint marks, which indicate the nut or bolt has been properly torqued. Suspension bolts usually are marked in such fashion.

[lowrydr310]

I took my cover off to check an oil leak when I bought my car and just left it off. The first time I went for a test drive after that, the transmission cover caught some air and started scraping on the ground because there were bolts missing so I removed that and left it off as well.

I didn't reinstall the covers because the bottom of my front bumper is so horribly scraped up that most of the bolt heads were worn off, and there were even a few missing bolts. Once I get all my mechanical stuff sorted out (still chasing a drivetrain clunk when load is reversed - rear diff input flange? u-joints? axles?) I do plan to get a new front bumper and then reinstall the cover for the aerodynamic benefits.

[tcphoto]

I will admit that I'm probably being overly cautious but the image below is what happened to a friend when a semi lost a tire on the interstate. If securing the belly pan keeps debris away, I'm going to do it.

[LMB335IS]

I've been driving without one for literally years in hot ass Florida. If anything it may help my car run a few degrees cooler. Over a half dozen 1/2 mile events with no problems either in aerodynamics or stability. If you spend any amount of time under your car, toss that thing. If it's someone else's problem then leave it.

[vilord]

Just to throw my opinion into the ring here:
Will the 5 lbs or air gap or any of those things make a difference? probably not.
Will it protect the underside of the car? maybe a little.

Biggest reason I replaced my under tray? The front bumper is not held securely at the bottom without the tray. The tray stiffens the bumper. Without it, a few years ago, the bumper started to sag on my wagon and both left and right fender liners rubbed against the tires and got holes.