WARNING....SPLASH SHIELD CAUSES RUST TO SUB-FRAME!
 

What a disaster.....!

A couple of weeks ago, I accidentally dropped a hose clip down into the engine bay. Looking from the top of the engine bay, I couldn't find it anywhere! So, I decided to look underneath and figured it may be sitting on the topside of the engine splash-shield/guard.

So, after removing the 14 bolts/screws from the shield, and dropping it down, I finally found the clip. But what else I found was shocking!

The whole of the front of the sub-frame and the splash tray mounting-bar had been heavily rusted. In fact, the front mounting bracket for the LHS torsion strut (lower control arm) had completely rusted away! (see photos 1 and 2 attached).

How did this happen? Well.........it turns out that the plastic splash-shield has moulded wells in it, which are mounted flush around the front of the sub-frame (large bar and control arm mounting bracket); and the splash-shield mounting bar. Also, the bumper acts as a funnel for rain water, to flow onto the topside of the splash-shield.

BOTH OF THESE PLASTIC WELLS HOLD POOLS OF WATER, AND HAVE NO DRAIN HOLES! ANOTHER BMW DESIGN FAULT? If you live near a beachside suburb like I do, or drive on salt-laden roads in the winter, these wells could be full of salty water!

Anyway, to fix it, I had to buy a rust-free sub-frame from a wrecking yard and have the rusted section cut out and replaced by an expert welder.

The whole procedure took about 2 weeks to organise and about $700 to repair. I spent about 4 hours removing and replacing the splash-shield, splash-shield support bar, brake/transmission cooling duct and bumper. All caused by having no drain-holes in the splash shield....NOT HAPPY!

Needless to say............ my splash shield now has 4 new drain-holes to clear the pooling water away from the frame components (see picture 3.)

This is a warning for other e53 owners. If your X5 is around 10 years old, you should remove your splash-shield, check for rust on the metal frame and create some drainage points.

Let me know if you have experienced a similar problem.

holy shit. i can't believe the rust. you must feel a difference in steering/suspension with the replaced sub-frame I assume?
I live in an extremely dry climate (sadly) so this is not an issue for me, but I may as well check it... no harm, just time.

Didn't notice anything of this nature on mine... came from Utah and then California but not sure how much salt it saw. Here in TX it won't be an issue... but I will be putting in drain holes anyway.

Thanks for the PSA.

Holy shit. I have not seen that on mine at all. Nothing even close. And I live in NE. I do keep mine in the garage and wash after every salt drive. But wow.

From what I've seen on my E53 (10 yrs in "rains almost every summer afternoon" FL), there's something more then just water at work here.

Those areas on my X still have the factory black coating.

That shield drains water, the front is higher then the rear when installed.

It looks like someone parked the X in salt water for a few months!

Mine is like brand new due to the leaking power steering return hose :(

My oil pan seepage has created an effective moisture barrier to several underbody components :thumbup:

2002 X5 3.0 298,000 miles
2014 428i 16,900 miles (I get to drive the CEO's ride this week!)

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

:iagree:

:iagree::iagree:

Mine looks mostly factory new.

But I am extremely curious, why cut and weld on the sub frame? Just replace the whole item!

Quicker/cheaper/fewer labor hrs grafting the subframe vs replacement.

Thanks for your interest, guys. Looks like I'm the only one with this problem, so far.

For further information on my X5 sub-frame issue.......

The car was purchased new by me in January 2005. It has never been immersed in salt water or been used for beach driving.......although there is sometimes salt in the air due to ocean breezes.

The car has spent half it's life parked outside the garage on a flat concrete driveway, and is only used 2-3 times a week. The splash shield had never been off in 11 years.

The water definitely pools in the splash shield, around the sub-frame components.......just look at the rust stains on the top of the splash shield (which I couldn't remove).

And yes, as far as the repair goes.........it was much cheaper to do the 'cut and paste', as it was relatively easy to access.

A mechanic, after scratching his head, quoted 15-20 labour hours to do a complete swap. Bonnet off, support engine from top, engine protection plate off, steering out, suspension components, sway bar and struts off, engine mounts off, replace everything, fix anything that breaks in the process, new wheel alignment. It probably would have cost me over $2,000.

Anyway, now it's all good....the repair is neat and tidy and strong. The car also handles better, no vibration when braking at 80-100kph, and most of all, I have peace of mind that the control arm is not going to fall off and cause a serious accident.

Of course, in my case, all this could have been avoided if only the splash shield had drain holes in the relevant places.

Lesson learnt for me...........occasionally check the complete underside of the car, particularly under shields/covers etc.

I noticed a little rust there last year on mine. Just getting started. So, being OC about it, cleaned the rust off, Por-15 the subframe, and drilled a dozen weep holes so the splash pan couldn't hold water.

Adding another minor task to my Easter weekend task list (and putting my drill on charge.)!! :yikes:

Do you know if the car has been in any front end accidents before you owned it?

Seems weird, unless in your particular area has a very high salt concentration from ocean breeze/waters etc even then doesnt add up too much as im sure people on this board that live close to the coast would have same issues..

Me and a few other e53s drove our cars through some salt water a long time ago and everyones frames and undercarriage parts are black as the night- no rust. Adding to that we live in the northeast and the stuff they put on the roads in the winter is probably 20x worse then some ocean salt water.

I know they dont however me being anal i jack my car up in spring and pressure wash it all underneath- during the winter stages i do run it through a touchless wash that sprays the undercarriage down as well however thats a quick spray and not thorough.

Hello 4.8isX5,

Mine is a 2004 3.0i with a sports pack. I've owned the car since new, and it has never been in any accidents. It has done 160,000 klm and it is in very good order (no signs of rust anywhere else). I must admit, I have never bothered to wash down the underside, though. It's always been a 'good driver'.

Thankfully, I haven't had much go wrong with it to date..... only 2 wheel bearings; front door handles stuck; panoramic sunroof broken caused by sun and heat on cheap plastic fasteners; one parking sensor broken; MAF sensor failure.........Mmm, they all add up, don't they.

All these issues have been fixed with the help of this forum!

FYI, I attach a photo of the repaired sub-frame, for those interested.

Is there a "nose down" slope of the concrete pad where the X is parked?

A slight (or excessive) "nose down" parking attitude would pool water.

Hello TiAgX5,

The driveway has a very slight (2-3deg.) slope. When I park the car, it actually sits "nose up".

I think it has been slowly rusting away for around 4-5 years. Once the rust starts at the bottom of the frame, the rust draws the water up higher and higher above the pools........sort of like a 'wicking' action.

The slight front-end vibration when high-speed braking, started around 1 year ago. It wasn't bad enough to cause me to investigate. I suspect, in hindsight, that that is when the front control arm bracket actually fully disintegrated! Thank goodness the rear bracket was still untouched and is very robust.

Just as well I accidentally dropped that hose clamp down into the engine bay a few weeks ago. Otherwise, I would not have discovered the problem!

Wow! That was a scary pic. Thanks for the alert. Too bad your X didn't come with the *feature* of automatic power steering fluid rust proofing like mine... :cool:

Repair looks nice. Glad you were able to get it sorted.

craig,

You probably live next to the ocean in Australia.

I'm at a total loss for a cause if this X is parked nose up.

In the past I've heard of stored vehicles sustaining damage by unfixed cats marking territory. Their "spray" is caustic and strip paint/stain chrome & aluminum/rusts steel.

if you get this must corrosion in an area that is NOT noticed by most others in the Salt Belt capitals of the world, then I implore you to look at the brake lines behind the left front wheels. they are covered by plastic that also traps water/salt and attacks the metal brake lines, as there are a few good threads here about this exact problem adn a potential solution with an extra hole drilled into plastic and using a normal garden hose to push up in this recess and flush the area time to time... just a thought for you.

I am curious if leaving the splash shield off is an option. You would notice leaks faster if it was off. I have mine off on my manual to keep an eye on a leak and avoid driving it in any wet weather. I thought that if the splash shield was off and water hit the alternator while driving, it would fry it. Am I wrong?

I've driven many vehicles for tens of thousands of miles with no splash shields with no ill effects.

Unless you are fording streams or flooded roads frequently... you'd be fine.

Having worked in a few GM assembly plants, I'm reasonably sure the subframe arrives to the line already painted. There is the remote chance that this subframe was not adequately prepped before painting and still had some oil residue from the forming process on it when it was painted. After some time, the paint itself would disappear and leave the raw, mild steel to readily rust away in a salt air environment. Based upon some of the rust visible on other components in his "as repaired" photo, I'd say he's definitely in a salt air environment.

2002 X5 3.0 298,000 miles
2014 428i 16,900 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

I don't recall ever hearing of this type BMW problem before. Even in the good ol' days when rust was a huge problem with American made vehicles something this bad would be very unusual.

Lots of things could have caused the rust to get started but once it did the chloride in the saltwater air and high humidity would be excellent growth hormones. I don't think the shield had anything to do with it. My guess is there is a list of extremely uncommon circumstances that are the culprit not even normal to a saltwater environment.

I certainly don't see the need for a worldwide rust alert. Drill holes in the shield it if it makes you feel better but I wouldn't remove it entirely--it is not window dressing it is functional.

Thanks for your input, everyone.

Just to draw a conclusion to his thread, my conclusions are:
1. As I live in a beachside suburb (about 500 metres from the ocean) there is regularly salt-laden air in the breeze.
2. That air contaminates the small pools of water that often occur (by rain flowing down the bumper and through the grill) on the topside of the splash-shield, right next to the sub-frame.
3. When the pools of water dry out, the salt crystalizes out and actually stays in the plastic wells on the shield.
4. The ongoing cycles of water/salt air/evaporation actually increases the salt content in the pools, many times over. The salt concentration, probably ends up higher that ocean water?
5. Once the rust starts in the immersed sub-frame metal, the porous rust draws the salty water up to the rest of the frame, with a wicking action.

I am sure my new drain holes, will stop this cycle happening again.

As far as the splash shield goes, I think it is really meant to have only 2 purposes: Prevent stones from entering the engine bay; and to slightly improve the high-speed aerodynamics/fuel economy.

In my case, it has caused the rust to occur in a vital structural component, and also prevented the visual discovery of the problem, until it was too late.

Thanks to Clockwork for suggesting I check the brake lines also.......I will definitely do that.

And thanks to this forum for helping me out over the years.
....Cheers.

Best of luck going forward.

Thanks. I want to keep the black plastic splash shield off until I get all leaks resolved on the 5mt.

I am pretty sure it is my OFHG. It turns out that Bav Auto sells a Viton OFHG gasket for 19.95 that "will" last the life of the engine. I am going to get one and replace that and hopefully with the very tough Viton, it will last 15+ years. Or forever.

I had a power steering fluid (ATF) leak to clean up today so I removed the under-shield - the subframe looks to be in good condition.

http://i49.photobucket.com/albums/f2...psyxk9hzy9.jpg

The under-shield itself has a thick urethane foam insulator attached to the interior - maybe this is a diesel thing. I drilled some new drain holes while I had it off the car - seemed prudent in light of this thread!

http://i49.photobucket.com/albums/f2...psjxftojnl.jpg

Also noticed the A/C belt tensioner/idler pulley bearing is shot - was wondering what was making a slight noise lately - will replace it once I figure out what the exact part number is - the OEM unit has a shaft as well as the pulley/idler inc. the bearing (visible in the first image above). :confused:

I really do not think there is a design flaw here for all of the North East vehicles would have exhibited a similar effect. Something out of the ordinary has occurred with your vehicle. That sub frame has spent some time in an immersed environment with corrosive properties. Interesting none the less

I'm in PA; we get plenty of snow/road salt. My front subframe is still pretty much perfect. I've had the plastic tray off a few times though.

Those photos around the front bolt were certainly :wow:. That level of corrosion is not normal.

+2

That is crazy rust!

Well, I finally got around to checking my brake lines as suggested by Clockwork! It took me more than 6 months to get around to it.

Incredibly, all the lines were clean and rust-free.

All I had to do was unscrew the 10mm screws from the long plastic sill cover running from the LHS front wheel arch to the LHS rear wheel arch (no need to remove all those plastic one-use rivets from the edge), then pry the cover down about 2-3 inches from the inboard side. This allows a fairly clear view of all the fuel lines and junctions.