811d rusted front panel and door, can't work out where water is coming from.

[adz2024]

Repairing lots of rusted bits on this 881d I'm converting to a tiny home. The metal was very wet on the inside of the body, which leads me to suspect leaky window seals etc.Anyone have any idea how I would check and where might be biggest suspect? Also what to do about it. Kind of pointless repairing the exterior if it's rotting from the inside! (Heart break emoji) One of the ones I can't understand is big hole in second photo, front wing, where would water be coming from to get in there? Bottoms of doors also very rusted , suspect window seals, and tops of wheel arches where they meet corner of doors. Anyone had any similar experience? Can post more photos if needed.

 

[brandwooddixon]

I've found that often its not just a case of water getting in but it not being able to get out.

Any panels that you repair, assume that water will get in, treat internally with an anti-rust coating and ensure that there are drainage holes, door bottoms typically rust from the inside out. Wind-down windows are expected to leak, hence why manufacturers put a plastic sheet over the door interior to protect the door card.

Hole in second picture probably starting due to clipping the panel on a low wall or kerb which was then left to rust.

Assuming that you've removed all interior trim the source of a leak should be easier to find.

If internal panels are wet, use paper towel to determine how high up it goes, it could be condensation or a leak. If the paper looks dry, touch it to your top lip, just below your nose, a far more sensitive area to detect moisture than your fingers.

I don't know of these vehicles personally, but don't they have a gutter that runs around the roof. Check for possible leak there.
Rubber window seals are always a potential source and that includes the windscreen.

When sourcing leaks I tend to remove trim and puff a dusting of talc around the suspected area, then use a watering can or low pressure hose to direct water around potential leakage points. Start low, say in line with bottom window and windscreen seals then work work up.

If converting to a camper, remember to insulate the internal panel surfaces and ensure ventilation to prevent the build-up of condensation.

For the first picture I think that you should remove the wheel arch trim, prior to work.

 

[Rockron]

Pic 1 front wheel arch, is a hollow section formed from 2 steel panels very difficult to weld repair, a Polish firm on ebay sometimes has replacement panels, not perfect fits so some reckon! Obviously a very vulnerable position subject to road salt, spray you name it.
A thin anti rust manufacturers coating doesn't put up much of a fight.

PIc 2 As already stated this may be a rust due to an external scrape, but if from the interior then this is probably due to debris blockage of a fairly large drain slot formed between the wing panel and the inner wing. Water runs down the windscreen travels along a steel scuttle panel
then at each end drains behind the respective front wings running around the wheel arch and should drop (barring debris blockage) to the exterior roughly where your wing has rotted. The wing is easily removable, no spot welds, just unscrew at the door jamb & along the wing top, unfasten bolts securing front grill and wings, cut sealant/bond between inner and outer wing.

If you don't mind being depressed I can point you in the direction of where you'll find areas of particular rust vulnerability

I guess you have an early 90s Type 2 811d panel van. Mercedes vans of all eras unfortunately, are not renown for being particularly resistant to rust, to say the least. On a positive note at least the 3972cc om364 engine, so called million mile engine is unlikely to rust out
before the body.

 

[adz2024]

Thank you so much everybody! Been away this weekend.

This is excellent information. I've wrapped it up against the rain while I finish exterior repairs. Got one more coat of paint then I can inspect it properly.

Rockron yes it's a 1997 811d

I'll inspect the scuttle drain as best I can and post some more concerning photos . But at least on the plus side hopefully I can slow down this problem before it gets too serious. Wheel arches are in a sorry sorry state possibly related if these drains haven't been working properly. There's an area on both sides where the inside corner of doorframes just below the hinges are particularly bad. Appear to be rotting from inside out too.

 

[adz2024]

I've found that often its not just a case of water getting in but it not being able to get out.

Any panels that you repair, assume that water will get in, treat internally with an anti-rust coating and ensure that there are drainage holes, door bottoms typically rust from the inside out. Wind-down windows are expected to leak, hence why manufacturers put a plastic sheet over the door interior to protect the door card.

Hole in second picture probably starting due to clipping the panel on a low wall or kerb which was then left to rust.

Assuming that you've removed all interior trim the source of a leak should be easier to find.

If internal panels are wet, use paper towel to determine how high up it goes, it could be condensation or a leak. If the paper looks dry, touch it to your top lip, just below your nose, a far more sensitive area to detect moisture than your fingers.

I don't know of these vehicles personally, but don't they have a gutter that runs around the roof. Check for possible leak there.
Rubber window seals are always a potential source and that includes the windscreen.

When sourcing leaks I tend to remove trim and puff a dusting of talc around the suspected area, then use a watering can or low pressure hose to direct water around potential leakage points. Start low, say in line with bottom window and windscreen seals then work work up.

If converting to a camper, remember to insulate the internal panel surfaces and ensure ventilation to prevent the build-up of condensation.

For the first picture I think that you should remove the wheel arch trim, prior to work.

Brandwooddixon, thanks so much for the very useful advice! I hadn't actually realised to trims were removable when I started grinding the rust back. I'll double check next week, and see what state the bolts are in. I fear the wheel arch and bolts might be so badly rusted that removing them might create a bigger monster than I'm able to deal with this year, as I'm doing the work outside , that may have to wait till summer 2025 or have the garage take a look.

Does anyone know if it's possible to remove and replace entire front wheel arches on 811d? They look pretty miserable to my untrained eye. Will try post photos next week.

 

[adz2024]

Just reread your reply properly Rockron, think you answered the immediate question in my head that it maybe possible to replace front wheel arches. They look pretty awful underneath, will post pictures. Might be a job for next year. And yes I think I'm ready to hear the depressing / exciting news about the rust vulnerabilities. I'm breathing into a paper bag in anticipation !

 

[mioba]

Once you start with grinding/welding, you wont stop till it is perfect.

Find all your bad bits and get the panels in - find a coachbuilders to direct you.
Repair panels are cheap, Its the prep, welding and tidying up.

 

[Rockron]

I note belatedly that your 811d is a horsebox, so most likely not a panel van body but just the cab with rear box for the geegees. Which ironically is a big plus point, because less Mercedes tin work the better!

Even so, if you're not a competent welder, or at least willing to learn the work involved in rectifying the rust decay to a decent standard, then paying for a competent bodyworker/welder is likely to run to a significantly large bill. Still if you are lucky and the rust is confined to just the areas you've show, then it may well be economically viable to get a pro welder to make good. If you're intending to carry out just a body filler bodge then........

The other cab areas nearly always affected by rust are the windscreen frame. Windscreen needs removing to inspect the frame closely behind windscreen rubber. Commonly corroded are the inside the windscreen A pillars, this is due to condensation on the inside face of the cab roof running down the pillars under heavy braking or parked facing downhill, this is probably what you can see at the door hinges.

If you remove the black painted steel drain panel below the windscreen (4 screws, wipers, bonnet seal) this exposes the scuttle area, notorious for rot. Steps often rust plastic liner easily removed on passenger side, but requires seat detachment on drivers side.
Door seals don't prevent rainwater dripping into the door cavity even when new, in fact the 'seal' on the exterioir and interior is just a fur
strip preventing rattles and debris entering the door cavity, water id supposed to drain out through the bottom slots.

The Type2 (yours) was discontinued in mid 90s and was superseded by the Vario which, with minor differences ie front wings and grille is essentially the same body/chassis, this was discontinued by MB in 2013, Some of the panels are still stocked by MB and some of the commonly rust ridden body elements are available as pattern parts usually requiring a bit of fettling to make fit and thin gauge steel as in 0.5mm
I've attached a few Pics front wings, grille, and drainage panel all easily removed no drilling, hacking or butchering required

 

[adz2024]

Thanks ever so much! All excellent info. Will give this a reread and look at the point you have given and get back to you with a few more photos when I unwrap her later this week.
I've done "bodge job" where easily accessible and has good metal all around, and very small areas of bubbling paint I've sanded back and put filler, primer ,paint just to stop it spreading. I've left the serious and fiddly bits for now e.g. under hinges. I've just removed the rust, primed and painted with rust inhibiting primer without filling holes and coach paint until someone can have a proper look.

 

[adz2024]

I just reread your reply, think it's starting to make sense now. This week got a bit of dry weather so I'd like to get the tarp off her and access scuttle area. Do you think it might be a case of cleaning this out and making sure drains are clear ? Or are there commonly more serious issues ? I've attached photos of under wheel arches. Water is coming down from scuttle area I think into the arch area and tracking out the front wing near the headlight where that big hole is I posted a photo of initially. I noticed water dripping out of that area during rain, now I've covered up the windscreen and scuttle area with a tarp it's stopped dripping from there.

Wheel arches look pretty awful to me but might be normal? Is the water from scuttle area meant to drain through the arches? Seems strange. Would be interested in your opinion on whether repair / replace is best option. Obviously is beyond body filler repair. Going to try to go nothing initially as it's not failed it's historical mots on this (yet), and conversion already cost me £30000 so far

Has it's mot on 31st November do can ask garage their opinion but I'd like to stop the water dribbling down there myself if possible before then for obvious reasons.

I've attached photo of what I think you called "A pillar" under door hinge. From what you say this is lilkely to be condensation ? Could it also be rain coming in down scuttle area? I only ask because I blew smoke up the rusty hole under hinge and the smoke came up out of the corner of the scuttle area so I assumed rain might be getting in from the top.

Not sure how to stop this water running down the pillar, or if it's even preventable if it's condensation.


Have attached some photos of painting touch up midway through and the external cladding just for the sake of interest.

 

[Anthony Salvatore]

For the window seals, check for cracks and do a water test to see if it leaks.

 

[Rockron]

I've got to be honest, but those wheel arches (the inner arches particulary) do appear to be in a bad way. The plastic wheel arch fixing screws appear to be held mainly by rust That hole at the base of the 'A'pillar should not be there it's rusting from within and rainwater will be constantly seeping and getting up to no good.

Additionally, as I mentioned in a previous post those 'A' pillars support the doors and frame the windscreen, a kind of tube.The steel cab roof gets condensation on the underside, it drips to the steel frame along the windscreen head, then drains along this to the the vertical pillars and then down these to where they meet the wheelarch.There's a purpose made drainhole at the base. This pillar has minimal rust protection, hence the rust, one of the pressings forming the member is at least thickish steel after all it has to support a 2m high door a blowing in the wind. Also removing the scuttle panel below the screen will reveal a fair bit just 4 screws and remove windscreen wipers arms at spindles, don't break the plastic end grilles these stop all sorts of crap getting into the cab venting ducts! I have one 2 pics somewhere showing what to expect when dismantled I'll post off if I find.

That cross head screw near the painted over rust hole is one of 3 or 4 fasteners holding the front wing rear on, there are others on top of the wing. Not a difficult job to remove the wing, no cutting or kicking , but you really need to get the wings off to get a good look at the extent of the rust lurking behind. A fair proportion of the cab is bolt and screw fixed, think of it as a giant bit of Meccano, albeit a rusty giant bit.

 

[Rockron]

Here we go, these pics should give you an idea of what to expect. Would have taken more salient shots had I reckoned on
them being possibly of some use to some one some day!
606 shows the the A pillar just right of door edge from windscreen down and welded to the wheel arch. This is heavy gauge steel and
where you appear to have penetrating rust eg the rust hole in your pic. The site doesn't permit large files so I've rescaled, so not as crisp as could be.

 

[adz2024]

Thanks yes that's really helpful. Going to take it into a barn and have a proper look at this scuttle area. I'll ask my mechanic what he thinks about these A pillars. Thanks again for taking the time to post this!