Corrosion in Electrical Connections Underbody

[Ali Donald]

Hi Folks,
My 2018 T6 has corrosion in a few different electrical connections under the body of the van - especially leading to the Adblue control unit. VW dealer replaced this 3 months ago and its corroded again already. Does anyone know of any common places for water ingress, or if its possible to protect the underside more from spray off wet roads? Thanks!

 

[Shaun Witts]

Any connector in such an exposed location should be adequately specced for the environment they are in, so it is concerning that this is corroding within 3 months of being fitted over the driest summer on record!
Does your van still have the under trays fitted? They will reduce exposure somewhat, but they do have a tendency to go missing if driven through floods (or deep puddles) too fast.
Wrapping some self amalgamating tape around the connectors might help, though this might make future separation difficult. A liberal dose of grease (dielectric grease might be best) would also help. I would probably try a combination of both (assuming access to the connector is good enough to cut the tape off in future).

 

[Ali Donald]

Thanks a mill. Yep, she was in France most of the summer and had 2 days of rain. The problems cropped up again 2/3 weeks after getting home to the west coast of Ireland...

 

[DXX]

Fresh water doesn’t cause significant corrosion, saltwater (seawater) will destroy electrical connections especially if live.
Are you sure you haven’t been through any tidal fords, seawater puddles etc.

 

[Salty Spuds]

I’d echo the thoughts of the others, the connections should be sealed & take anything that’s thrown at them. It’s an odd one. This is my “go to” product for sealing/corrosion protection. We used it in the coal mines/sewage works/boats & trailers. Brilliant stuff, easy to use & does what it says on the tin. Not expensive either. I’ve no connection with the company.

https://www.specialised-aerosols.co.uk/METECT

 

[Loz]

Got any photos?

 

[Ali Donald]

Thanks folks. While I live in a coastal area, I've been super careful to stay well away from any saltwater at all- genuinely can't think of a single occasion making contact with seawater. I had a T5 before this and ran a sea kayaking business for 10 years from it with never a problem. I'll attach some pictures here. It is converted as a camper with pop-up roof and I wonder is it possible that there's a connection here...

 

[Salty Spuds]

Without overstating the “Bleeding obvious “ that’s not right. You should be able to submerge that connector without any issues. That doesn’t even look like fresh water corrosion, is ad-blue leaking from somewhere & running down the cable (possibly inside) & into the connector? Something is very wrong there & you need to bottom it out.

 

[Loz]

To me, that looks like moisture has tracked (capillaried) down the conductors, as the seals themselves look fine. The photo with the corrosion on just the 3 pins in the middle demonstrates this.
so the question is, did these cables suffer previous rodent damage? And was the repair just to the cables, as that looks the most likely cause to me.