UKH

Hello groovy gang. I have all the mechanical skill of a sea anemone but also little money. Our 2004 diesel corolla developed a noise, vibrating metal on metal noise.

I looked underneath today and there is what looks like a sheet of metal which is about 4mm thick, shaped to fit and bolted to the bottom of the car. My guess is it is to protect what is above it from road crap and rusting. The sheet itself has rusted and come away from at least one of the bolts. 

What might this be called? Is it a big problem to just take it off? Any advice gratefully appreciated. 

sound like you are describing the undertray.

Should be fine with this off, it is coming into winter through and they’re be a lot of water and salt on the roads so you’d be better with  on. Look at fixing it 

Rather depends on where it is - between the car and the exhaust, the a heat shield of some sort and that would need to be replaced.  If not, then as above.

However, 4mm is thick and suggests something rather more structural.  Does it appear to be anything more than just a sheet of metal?

Thanks for replies. 4mm is an utter guess and probably wildly inaccurate. 

It is between the exhaust and the car in the middle third of the car length. 

If I can be reasonably sure of the name I could buy one from eBay or scrappy and replace. 

It's the heat shield between the cat and the car, the catalysator gets very hot and you need it!

Thank you

I have had another look. The metal is actually more like 1mm thick. It would sit closely to the car and a couple of inches about the exhaust pipe. Definitely not structural. 

Heat shield then - easy enough to replace if you can get underneath it enough, else a pig.  Parking on the pavement will help if you're happy to lie in the gutter  - not that I'm casting aspersions at all!

Grab a picture of it, go into the garage armed with your reg no. and ask.  Toyota have a fixed rate for some jobs and you may find that the tally for that job is so low for it not to be worth your while fighting with old rusted bolts when they could put it up on a ramp and have the job done in 10 minutes.

Handful of self tappers will bodge it in 5 mins. 

What Cheese Monkey said could work, though if it's rusty beyond a certain point, it might not be long before you need a new one. 

Which is fine until you put them through something you shouldn't have, like a cable inside the chassis.

It does sound like the heat shield, although this shouldn't be rusty as these were made of aluminium when I used to work for a company that made them for Toyota.

It's reasonable that someone with the mechanical abilities of a sea-anenome thinks corrosion and rust are synonyms

It's the exhaust heat shield, as already mentioned.

Had same issue with it on a previous car. Cheap option is to take bolts out* (assuming they haven't seized), put some large penny washers in and do it up again - they're often a bugger to remove without taking the whole exhaust system off, anyway.

Conversation at garage at it's next MOT went along the lines of "it's a bit knackered, those washers won't hold it forever", to which I replied "when they give in, I'll put some even bigger ones on"...

Otherwise, do as Nniff said.

* - sucking eggs and all that, but don't do it when the exhaust is hot!

Thank you all for your responses Going to ask the garage how much they would charge and then decide from there