Rust behind the plastic cover underneath the engine.

[Cavilln]

Please shout if this is covered elsewhere.

My Cali is 2005 but only about 70k miles. A mechanic discovered significant rust under the engine compartment, when the plastic cover underneath was removed. He had to scrape away significant rust that he said would become structural and an MOT failure within a year. He said they see this on lots of VW and similar vehicles that use these underbody plastic aerodynamic things (sorry don't know the proper term). Said they trap moisture against the metal and basically keeps everything wet. His proposed solution was to remove the cover for good (it is only cosmetic/aerodynamic) and treat with anti-rust gunk.
- good idea?
- anyone else experienced this?

Thanks!

 

[rod_vw]

When the T5 came out the dealers and converters were told that the under chassis plastic shielding was not to be altered or removed. However as far as I am aware its real purpose is to improve air flow under the vehicle i.e. to get it within the emission figures of the time.
My personal advice would be to remove the plastics, clean up the surfaces and paint and treat all necessary parts then replace the plastic shielding. My top coat of treatment would be a Waxoyl product or one of the similar products.

 

[AlanC]

Come the MOT the splash shields are not removed, so if there is any rust between the shield mounting and the chassis it is unlikely to be seen until the rust appears from behind the plastic which will prompt the tester to poke around further.

I agree with Rod that removing the shields and treating any rust early is very wise but I would replace them when the work is done. Should then last another 15 years.

Alan

 

[WelshGas]

I think a lot depends on the use of the vehicle. As an everyday vehicle I very much doubt there is much of a problem, but being laid up for prolonged periods, unless indoors, then could be problematic.

 

[Borris]

Can you supply photos? Have you actually seen this issue with your own eyes? It sounds rather unusual to me. I'm no professional mechanic but have been messing about with all sorts of VWs and VW based vehicles for very many years. I also owned an 02 T4 van with under pan. That had no rust at all in the area you describe. However I agree with Welshgas that use and envirionment will have an effect. Do you live near the coast?
Whilst it is normal for suspension, antiroll bars and other heavy components to rust, I find it strange for there to be serious body/chassis rust especially around the engine. Most if not all VW body shells have been galvanised for years. Having said that, I'm not sure what anti corrosion measures were taken on early T5 Calis and confess that I have never actually worked on one.

The under tray being the cause sounds rather implausible to me.

 

[Cavilln]

Thanks very much guys very helpful as usual. The mechanic took photos I'll try to get them