Ever seen a broken inner fender? - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 07-24-2006, 01:52 AM

As the attached photos will show, the passenger side inner fender of my 1985 300D (CA version) has several large cracks or breaks. I photographed the cracks from above and from below, with a trouble light on the other side each time to shine through the cracks.

I can't figure out what might have caused this.

It's been on the car for as long as I have had it (4 months). The PO never mentioned it but he was a short time owner and probably never saw it. By the looks of it (accumulated dirt), it happened a long time -- years -- ago. It doesn't seem to be doing any harm but I'm thinking about finding someone to weld it up.

Anyone ever seen anything like this?

Jeremy

#2 07-24-2006, 02:14 AM

It looks more like a rust hole than a stress crack.

Jeremy5848 · #3 07-24-2006, 02:28 AM

Definitely not rust. Sharp, clean edges. I'll try to take some better pictures tomorrow.

dkveuro · #4 07-24-2006, 04:11 AM

Those inner panels are stamped into shape and are under stress...if the car was in wreck , trying to straighten ( Pulling frame back out.) it will over stress those panels and you'll have what you have.

You need to look at the control rod mounts too.

If you find no problems....use body sealer to cover the holes.

.

Jeremy5848 · #5 07-24-2006, 11:13 AM

Quote:

Originally Posted by dkveuro

Those inner panels are stamped into shape and are under stress...if the car was in wreck , trying to straighten ( Pulling frame back out.) it will over stress those panels and you'll have what you have. You need to look at the control rod mounts too.If you find no problems....use body sealer to cover the holes..

Interesting! This may fit in with the little bit of overspray that I found on the front bumper. Perhaps there was an accident that I didn't get told about. If so, they did a good job of repairing 'cause there's no sign on the body that I can see and no remaining effects in handling, etc.

What do you mean by "control rod mounts" (I'm weak on front suspension)?

dkveuro · #6 07-24-2006, 11:33 AM

Those are the rods that angle at 45 degrees across from the lower suspension arm to the body chassis member . The socket they sit in at the rear, get a pounding in front end wrecks or hitting high curbs.

This adjustable arm controls/sets the caster angle of the front wheels and contributes to the straight line stability and self centering from a turn.

As they wear, they knock on rough surfaces.

.

t walgamuth · #7 07-24-2006, 07:32 PM

with dkeuvero

but i think another possibility is that they ran over something and it rolled up and was caught between the wheel and fender and punched the holes in it.

i agree with his solution too. i wouldnt try to weld it because of the welding introducing areas that will rust easily.

if sealer wont seal it i would add a patch of aluminum and use gutter seal to glue it in place with a couple of small screws or pop rivits if necessary.

interesting damage. i dont think i have seen anything quite like it before.

tom w

Jeremy5848 · #8 07-24-2006, 07:53 PM

Quote:

Originally Posted by t walgamuth

... they ran over something and it rolled up and was caught between the wheel and fender and punched the holes in it....

I hadn't thought about that -- it's certainly a possibility. It must have been something big 'cause those inner fenders are made of metal. I'm used to sheet metal or plastic GM crap; what will those Germans think of next! There doesn't seem to be any evidence of anything else in that part of the car being damaged and repaired or replaced. Everything is equally old and equally dirty.

If something happened, it must have been many years ago.

I'd like to seal it up before the winter rains get here. It will splash a lot of water up into the engine compartment, which I'm trying to clean up. I'm sure there are a lot of glues, patches, and sealers that would work, especially if I take the time to clean the area thoroughly first. I'll experiment.

Jeremy5848 · #9 07-27-2006, 01:51 AM

I showed the inner fender damage to my mechanic today. He thinks that, if something came loose or broke such that the upper control arm was forced upwards, it would hit the inner fender in just the right place to cause the damage shown in my photos.

He also said that it would not harm anything to leave it the way it is and just seal up the cracks with silicone sealer.

[Edit] Looking at it again, I can now see that that is what happened. Something broke or came loose and the upper control arm rotated on its bearing, allowing the outer end of the control arm to strike and penetrate the underside of the inner fender. Must have scared hell out of whoever was in the car at that time!

#10 07-27-2006, 02:13 AM

Can you find any other signs of damage related to that idea? It sounds like a pretty nasty event!

Jeremy5848 · #11 07-27-2006, 02:25 AM

I wish I had more experience with Mercedes! It looks like this event happened some time (years) ago and everything is dirty/oily, making it hard to recognize any changes. I can see no signs of metal that has been straightened or welded or otherwise repaired. Parts could have been replaced (the lower control arm might look a little newer) but it's hard to tell. You would have to lose both the spring and the shock for the upper control arm to have that much travel -- it must indeed have been quite an event!

Jeremy5848 · #12 10-10-2006, 11:59 PM

I finally got around to cleaning up the inner fender and patching the damage done in the unknown past. After thinking about silicone glue for the longest time, I finally decided to use 3M Strip Calk, as its sticks well but is removable.

My rusty battery tray is in the background. I suppose I should replace it someday. Anyone got one to sell?

Jeremy

pawoSD · #13 10-11-2006, 12:28 AM

Quote:

Originally Posted by Jeremy5848

I finally got around to cleaning up the inner fender and patching the damage done in the unknown past. After thinking about silicone glue for the longest time, I finally decided to use 3M Strip Calk, as its sticks well but is removable.

My rusty battery tray is in the background. I suppose I should replace it someday. Anyone got one to sell?

Jeremy

Looks good! As for the battery tray, take it out, sand it down a little, paint it with POR 15 or some other good anti rust paint, give it a second coat of something else (if its POR) then install. My dad did this to his and it looks great (was very rusty when removed, now it looks perfect, total cost? few dollars for paint etc...)