Giant gash/slice in van frame above fuel tank

[4wheeldog]

The previous owner said his recollection of the towing three years ago is that the vehicle was pulled on the flatbed face first, so it's unlikely that tow job was the culprit, as the tear goes from front to back.

If a hook was placed in the hole as a tie down, it could have torn when the van was rolled off the tow bed.
Which is more likely than trying to pull it on by the same hole.

 

[billintomahawk]

Obviously he dropped his cell phone/Rolex down into the frame from the inside and it disappeared from sight.

Of course he was drunk and decided to sleep on it and do the recovery in the morning.

Morning comes,,,where is it, where is it??

Get the nibbler,the porta-power and a Hyjack.

His wife stopped him before he destroyed the van.

My guess is it's still in there.

bill in tomahawk

 

[Kajtek1]

Now I understand that posting member never did inspection buying the van?
But what are the chances PO did not know about the tear for 3 years?

 

[220629]

I’ll throw my hat into the ring with a guess. What if a long chain or strap was left hooked into the forward hole and was then driven away. As the flopping tailing would go beneath the rear tire it would rip a small segment until clearing the pinch point. Each time it would pass under the tire it would rip a new segment until it was trailing the rear axel far enough to be out of the wheel path. This would explain the “can opener” type sections...

Interesting idea. A strap might not make as much noise dragging along, but you'd think a driver would notice noise of some kind. That said, just because they heard it doesn't mean that they'd stop to inspect... especially once the noise stopped.

vic

 

[OrioN]

Interesting idea. A strap might not make as much noise dragging along, but you'd think a driver would notice noise of some kind. That said, just because they heard it doesn't mean that they'd stop to inspect... especially once the noise stopped.

vic

For the first few dozen yards.....


...one should be able to hear the dog yelping.

 

[220629]

For the first few dozen yards.....


...one should be able to hear the dog yelping.

Oh-h-h-h Clark... not Aunt Edna's dog Dinky again.

vic

 

[Deleted member 50714]

What are the vertical brown stains to the right of the transition from diagonal to horizontal on the left side and at the end on the right side? Does not look like shadow to me.

Maybe cavity wax covered with road grime?

Inside of the channels are treated with cavity wax.

 

[jtr210]

The vertical stains appear to be black soot. I’m not sure why they are localized in those two spots, but it could be caused by the airflow patterns under the van.

After speaking with a couple shops who can’t do the work for different reasons, I made a service appointment at a Mercedes dealer (different dealer than two weeks ago), and the guy I spoke with said he has seen this several times before and it’s usually caused by a tow truck. He also said that a repair is probably not necessary and that the vehicle is safe to drive without the repair.

I made an appointment so they can evaluate the situation, but the guy said Mercedes might not even be able to do the work and that I’ll probably have to get an outside body shop to do it if it’s deemed necessary.

I guess it gives me some small piece of mind that the vehicle is safe to operate, but I don’t totally believe it. I’m far from an engineer though, so I just dunno. ?‍♂

 

[Midwestdrifter]

It's not a big deal structurally, and it's not in a crumple zone.

 

[Kajtek1]

Sprinters don't have crumple zones. At least not in the rear.
I don't see how undercutting main frame member can be safe to drive.
It might be acceptable to some degree, but heck, how about cutting the frame completely out?

 

[Midwestdrifter]

The loss of vertical stiffness is minimal as the vertical member is mostly intact.

 

[OrioN]

The loss of vertical stiffness is minimal as the vertical member is mostly intact.

I disagree...

...at a minimum, the vertical stiffness is now reduced to the strength or height of the metal above the hole were the tear started. Secondly, a boxed frame is significantly stiffer than two separate vertical plates.

 

[Midwestdrifter]

If someone wants to send me a dimensioned drawing I will run an FEA.

Regardless we are talking about a unibody with several alternate load paths. I have seen mis drilled holes wipe out a whole member with no obvious effects.

 

[Kajtek1]

If someone wants to send me a dimensioned drawing I will run an FEA.

Regardless we are talking about a unibody with several alternate load paths. I have seen mis drilled holes wipe out a whole member with no obvious effects.

I on other hand have seen lot of rear fender benders bending van body over the rear axle.
There is a topic about it in NVC3 section.

 

[Midwestdrifter]

I on other hand have seen lot of rear fender benders bending van body over the rear axle.
There is a topic about it in NVC3 section.

That's my definition of energy absorption.

 

[OrioN]

 

[CJPJ]

Add the powerful relative slow pulling speed of the Wench and the wench cable elasticity relationship of its length and the sheetmetal yield caused oscillation waves produce scalloping seen in the pictures.

That attempt at backward extraction doesn't indicate the van moved from its position (be it in a ditch, snow bank etc). A second attachment point was needed (rear wheel, rear axle ..) to continue the course of recovery.

 

[220629]

It's not a big deal structurally, and it's not in a crumple zone.

I agree FWIW. I wouldn't worry about driving it until repairs can be effected.

Why do I say that?
Look at OP pictures. The torn metal isn't near any spring mounts. What stresses will that section see? Maybe the tank support strap? Unibody construction means that channeled flooring and other parts contribute to the structure too.

I'm not saying not to get it repaired. I am saying that I don't see any imminent doom by driving it for a bit longer.

vic

 

[Deleted member 86082]

The box beam is under compression at the top and tension at the bottom with no stress in the middle. That's why the large holes are in the middle section of the beam. With the tear at the front of the beam from the hole to the bottom, you lose the tension strength of the beam by 50%. I would not load the van at all until this is repaired.

 

[Midwestdrifter]

A bit OT, but I bet that damage reduces the frame stiffness of the chassis in the vertical plane by less than 20%. The skirt/rocker panels are an enclosed beam structure, and the walls and waist beam will also bear some load. When you think about it, a ~16 gauge beam of that size has limited load carrying capacity to begin with.

I would also note that the bottom face of the beam/is intact, so it will continue to provide load bearing for the undamaged vertical face.

Rough estimate is that that beam (in isolation) is at 75% capacity, but that depends on how the load is distributed, and the end conditions/restrains. That single beam likely does not account for more than 25% of the stiffness of the chassis in the vertical loading regime. While simplistic, that would be 0.25*.75= 19%.

Thinking about this some more, An acceptable repair, may be simply to reinforce the area around the hole. So 10" of bond on each side of the diagonal tear and hole with adhesive. Plus about 10 thread forming 1/4" bolts. This could be done without removing the fuel tank. Welding is also an option, but prep, tank removal, etc would be time consuming.

Now point loading of the floor? It may be possible to deform the floor and beam, if say a 2000lb pallet were dropped right above the damage