Chassis rust, Is this too far gone.

alexanderfoti

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Hi all

Pulling apart my Cl55, and am finding lots of rust under paintwork.



This is the rear subframe mounting area, behind the wheel arch trim. Not sure I like the look of the rear subframe mounting area.



This is the subframe and boot floor underneath.

The sill jacking point are also a tad rotten, where ill fitting jacks etc have been used in the past.

I think, if repairable, it will need a new subframe (or to dip this one) and treat all the rust on all 4 subframe mounting points and the sills along the length of the car.

I think I have made my mind up, but would like others thoughts on it.
 

daveenty

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I'd drop the subframe off it and then go through it all thoroughly before making any decisions.

My little 190E wasn't as bad looking as that but, when all the paint and rust was stripped off it, it still took a while to get back to an acceptable (to me) standard. Lots of strip and clean pads and wire brush drill attachments were sacrificed, but worth it in the end.

Once all that rear suspension's off the car it's a lot easier to work on as well. :)
 
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alexanderfoti

alexanderfoti

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I think that is the best option.

The rust you see on the side sections, is after I scraped back to clean metal with a screwdriver, so less likely to be hidden under paint at least.

Ill drop the subframe and the sideskirts and see whats what.
 
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alexanderfoti

alexanderfoti

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You've clearly never owned a Land Rover.... That would be considered excellent!

At least MB's consistently have truly random rust effects.

03 CL55 W/86k like this

02 C270 CDI W/122k nowhere near as bad...
 

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That is certainly no surprise given its age. Subframe out is probably a good shout. Have a good poke. If you can make a hole it'll need a bit of welding. If you can't poke through then grind the worst off, treat the rust and go for some decent paint-over-rust product. Keep an eye once a year. Treat again as necessary. I've welded up a couple of my customers w220 S classes in this area. Not difficult to do. Have a look at 2002 Fords if you want a laugh. People moan about rust on Mercedes, but Fords of a similar vintage rot horribly underneath, and the struggle is usually to find good metal you can weld to. What starts as a hole a half inch long can quickly become a foot long horror story. Anyone who has welded rusty cars will know what I mean when I say you feel sick to the stomach as you keep digging, and it keeps getting worse and worse!

To be honest Mercedes are usually pretty mothy around the arches and bumper joints before the rust on the underparts gets serious.
 
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alexanderfoti

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That is certainly no surprise given its age. Subframe out is probably a good shout. Have a good poke. If you can make a hole it'll need a bit of welding. If you can't poke through then grind the worst off, treat the rust and go for some decent paint-over-rust product. Keep an eye once a year. Treat again as necessary. I've welded up a couple of my customers w220 S classes in this area. Not difficult to do. Have a look at 2002 Fords if you want a laugh. People moan about rust on Mercedes, but Fords of a similar vintage rot horribly underneath, and the struggle is usually to find good metal you can weld to. What starts as a hole a half inch long can quickly become a foot long horror story. Anyone who has welded rusty cars will know what I mean when I say you feel sick to the stomach as you keep digging, and it keeps getting worse and worse!

To be honest Mercedes are usually pretty mothy around the arches and bumper joints before the rust on the underparts gets serious.


Absolutely. Its all still solid, no holes can be made, although I have found a small hole under the drivers seat. I think its worth pulling most of the bits off, as you say.

I think its a good stage to keep on top of it before it goes any further.

What I typically do with rust, is grind down to good metal, where possible, and then treat with Deox gel. Once done, I clean off and spray etc primer, then either a stonechip guard or a colour coat, depending where it is. I have little body shop experience, but this has done me ok in the past?

This particular car has had a good quality, full respray, so the outside is nice with no corrosion in the usual places. A bit odd why they didn't do a proper job when they had the opportunity, as the paint job is top quality....

I intend for this car to be a show vehicle for what is possible with tuning on the 55k platform, so it needs to keep going for a bit :)
 
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alexanderfoti

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I was about to post the same, I don’t think my Land Rover had that little rust when it was new...
Maybe I should (nt) buy a LR then? :)
 

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Maybe I should (nt) buy a LR then? :)
They’re appreciating assets! so if you want to make money by a Land Rover (or a 911). Just get a decent welder...
 

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Have a look at POR15 if you aren't aware of it. It's pretty good if you follow the application process.
 
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alexanderfoti

alexanderfoti

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Have a look at POR15 if you aren't aware of it. It's pretty good if you follow the application process.

I have used it in the past, but not had any of the vehicles long enough to observe the long term effects.

Im torn between, grind, acid, prime, paint, protect (bilt hamber) or POR15 treatment.
 

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I must hunt out my Mobilo warranty.
 

om613

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I have used it in the past, but not had any of the vehicles long enough to observe the long term effects.

Im torn between, grind, acid, prime, paint, protect (bilt hamber) or POR15 treatment.

Either would be fine.
Yes, that's what we do ... to benefit the next owner.
 

thebiglad

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Maybe I should (nt) buy a LR then? :)
LR Discoverys TDi200 and 300 - bodies would rust like a paying hobby : Boot floor, wheel arches, floor, inner and outer sills, front inner wings. Chassis is normally good.

Discovery II TD5 - Rear chassis can be like lace it rusts so bad. Bodies are usually surprisingly good.

Discovery III TDv6 - Good all over.

Defender - Rear crossmember, doors, front bulkhead all bad. However galvanised chassis, doors and bulkhead are now avail.
 

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Defender - Rear crossmember, doors, front bulkhead all bad. However galvanised chassis, doors and bulkhead are now avail.
Yes, however that takes all the fun out of ownership...:rolleyes:
 

charlysays

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That looks in pretty good shape to me tbh, I'd be very surprised if there were any holes.
My first W202 was a lot worse on the subframe mountings, as was my second. my third is better than the first two and probably better than yours but not by much.

I just walloped off all the scale I could with a hammer through screwdriver, chiselled the underseal off to expose it fully, treated with bilt hydrate 80, couple of coats of electrix then loads of dynax. 5 years later it was still rock solid.

I strongly recommend you check out a Kobe compact needle scaler. Will make prepping body work so much easier, even stripping back underseal.
 

peterws1957

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I have used it in the past, but not had any of the vehicles long enough to observe the long term effects.

Im torn between, grind, acid, prime, paint, protect (bilt hamber) or POR15 treatment.

I've used POR15 a lot in the past, but always on top of metal where I've removed 99% of the rust by acid dipping wire wheeling or media blasting. Use their metal prep first though. Did the underside of floorpans on one car and its still shiny and rust free 10 years later. You can paint on top of the coating as well. Expensive stuff but I think worth it. Don't get paint on the edge on the can lid though- you'll have to chisel the lid off!
 


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