Welding - worth it ?
 

Hey Guys, 2004 xc90 d5 has failed its MOT on rear subframe, needs welding apparently.

Is it worth patching it or getting one off eBay to fit? Pain in the rear as we need it for holidays next week.

I’ve not looked at it yet but is there a common fail point on these ?

no not yet, has it got holes? if you get another to fit get it galvanised first..

Depends how much they charge you to patch it... is that cheaper that buying a used replacement? If you need the car for holidays, that doesn't give you much time to source another subframe and have it delivered/fitted in time. If you get it welded, you need to get it rustproofed. Same applies if you get a used subframe.

On a car that's nearly 20 years old, corrosion is to be expected to a degree. If it needs welding, it must be in bad shape. I can only assume the car has lived in a salty environment and that's got the better of the underside over time because salt, mud etc etc wasn't washed off... Or the car hasn't had any rust protection applied since it left the factory.

Corrosion on the rear subframe of XC90s is common. Unlike the other P2 cars where they are all Ali due to weight of the XC90 they had to use steel. As they are getting on a bit now the early ones will start to show up on MOT. As long as it doesn’t corrode around the mounting areas of the body which it shouldn’t it is perfectly repairable although not a cheap repair.

An alternative to galvanising is hot zinc metal spraying:~
Briefly the part is media blasted prior to the above being applied- accepts paint (correct primer) then topcoats.
(Repair first or the above treatment will be wasted)

I have used this process on a 70 year old Riley chassis & quite a few other associated parts, the first company had been a metal spraying one (now closed) but I also use a company restoring narrow boats.
Parts had been done over 30 years ago and are completely rust free to date.

Prices have been very reasonable... the classic car interest from them helped.
Could be an option if you choose this route?

Good Luck.
Bob.

How much of a job is it to pull off the old subframe ?

Well, I’ve found a subframe from a 2011, everything callipers diff etc for £300 - question is will it all work with my 2004 ?

The ads I have just checked out suggest same design across MK1 so looking good; obviously wait for someone more knowledgable to respond or find a parts catalogue.

I now know why my 2013 R Design is whisper quiet on the motorway - separate subframe. Mine is as quiet as my mate's I-Pace In fact his has some wind noise at certain speeds so very happy with the XC90. Older Jag's have separate front and rear subframe - have an XJS which is also very quiet.

Good luck with the swap - will be a great opportunity to get under and rust proof everything while you are there.

BTW - once done you can be as smug as a Tesla driver as you are saving the planet by extending the life of an older vehicle. Of course not as clean when driving it but assuming you are not doing mega miles the pollution you are putting out is insignificant compared to the manufacture of a new car. I can understand stopping manufacture of certain cars but encouraging people to scrap an older car that is capable of many more years service is wrong, wrong, wrong. No doubt someone will shoot me down but I am fed up with people being encouraged to buy new - we need to get better at keeping stuff longer. Sorry - I will get off the soap box!

I believe they are the same for all MY MK1 XC90.

It's quite a big job, and often made more difficult by sieved bolts, snapped bolts and rounded heads. Allow plenty of time and I would just replace all the bushes.

A full alignment will be required after.

I would personally not weld a subframe unless the corrosion was restricted to a very small area.

Well, I now own a complete subframe from a 2011 with 120k miles, I’ve got pretty new discs and pads so will swap them over too, the bolts have been an absolute load of badger to get out so far, penetrating oil and heat is the only think that works!!

This car has been round the world a few times with me and brought three children home in it I’m not going to let it go easily !!

P.s you’re not allowed to weld it as it’s classified as a suspension component apparently