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Hi Gang

Not sure if this in the right section. I’ve had my van 11 years, sailed through the MOT this week but the garage said it would need a new front subframe soon as the old one is rusting through. I have searched on here but can’t find much on the subject. Has anyone else had to replace theirs, if so how much was the part, does anyone have a part number? The garage said it would take about two hours to fit which didn’t sound too bad but I’m bracing myself as expect the whole process won’t be cheap!
Thanks in advance for your wisdom.
 

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Has it spent much of its time at the seaside? They are known to get a bit flakey from the outside in on vans with an engine undertray, because crud gets thrown up from the road and lodges between the two. But on an 11 year old van I'd be surprised if it's anywhere near being a structural issue, because they are pretty thick steel.

If it were mine, I'd be inclined to take off the undertray (if it has one) and give the rusty bits a wire brushing, to see whether it really is in a structurally bad way, or just looking bad cosmetically. If the latter, a layer of rust-inhibiting primer and then an epoxy coat (e.g. Rustbusters two-part black) on top and I would think it should still be good for many years yet.

Longer term it may just need a litlle bit of attention each year. When I do my oil change I look for any bits of surface rust, and put a layer of Waxoyl on anything that's just starting to go through the factory coating, and that seems good enough to keep it protected until the next year.
 

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Mine was flaking around all the holes in the subframe. But not rotten. I wire brushed it then rust treated it and slapped some hammerite on it. Unless it is rotten I wouldn’t swap it
 

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I fitted an undertray 2 years ago, took it back off last weekend :)

Think that they may cause more harm than good, as Triffic says they catch crud and i believe also hold water on the frame around the weld points for the suspension components.

Wire brush, some form of rust converter (not required) then POR15 or epoxy 121 and reckon you will be good.
 

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No they dont all have undertrays, some have had them removed and alot of newer vans never had them fitted from new .
I always assumed that this was vw penny pinching but there may be other reasons why they weren't fitted.
 

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I don't think there's a clear winner, with or without. Mine has had an undertray from the factory, and it definitely keeps the lower half of the engine clean and relatively dry.

If you find that it's still acceptably strong, it may also be worth trying to spray something like Dinitrol or Waxoyl in through the holes in the frame to stop it from rusting from the inside out. Not easy to do though...

But we don't seem to get many threads about complete failure here, so they appear to be well enough made to survive to almost the 20 year stage without dissolving away.
 

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However mine is but rusty with tray. I have seen other without tray and they look less rusty.
not sure about the tray at this point.
 

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Think if you’ve got air con it’s worth having. My camper doesn’t have one and the compressor rotted out. The subframe has surface rust but so does my kombi’s and that’s got an under tray fitted. 🤷🏻
 

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My feeling is that as long as you know there’s a potential rot issue if a tray is installed and any accumulated rubbish is cleaned out as part of your regular maintenance, the progress of any corrosion can be managed with cleaning, paint and wax, whilst still reaping the benefits of having the tray in place.
 

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I was looking at replacing the subframe as came up on an MOT but did as others suggested and got underneath and tested for any rotten/soft parts and luckily it was just surface rust. Wire-brushed and waxoyl'd and no comments next MOT.

I used this site and was quote £140 for a second hand LWB sub-frame for my 2005 plate in case it helps >>>> Used Car Parts | Find Second Hand Car Parts (partsgateway.co.uk)
 

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You may want to consider power washing off you can, them spraying with a product such as Vactan Rust Converter and Primer who's rust converting process may highlight where issues are due to dried appearance - good painted surfaces just become shiney while converted rust takes a purple appearance. This would allow a review of where issues may be and allow a decision of if work involved in change out is required.
 
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