What would cause this corrosion in the Engine Bay?
 

I'm looking at buying a CX-5 as an extra vehicle from a non-Mazda dealership. Everything about the car seems great: 2021 Grand Touring, but high miles (61k) as a rental. The only thing that gives me pause is the high level of corrosion on most of the metal bits under the hood. Is this likely from somebody doing a bad job of degreasing the engine compartment? Harsh winters? Evidence of flood damage? (The spare tire area is spotless, so this seems unlikely) The alternator in particular looks pretty rough. This car lived its life in Kansas, according to CarFax.

I've done a search on this site and others, but I haven't seen anything that quite resembles this level of corrosion. Perhaps my google-fu is weak...

Anyway, thanks in advance for any insight.

https://cimg5.ibsrv.net/gimg/www.maz...ca3a7f90f4.jpg

https://cimg7.ibsrv.net/gimg/www.maz...a1e84ce10c.jpg

https://cimg8.ibsrv.net/gimg/www.maz...53e773c5ff.jpg

I used to live in PA. Lots of salt on the roads in the winter. The salty slush would react with anything aluminum and do that after a few years.
I have no idea what the road treatment is in KS, but that’s a lot for that age and it’s kind of uniform. Could well have been immersed in water more than just a splash.

I'm with Gozo.
But I lean more towards the salt.
I live in an area that is heavy with salting the roads in the winter plus I live right on the Atlantic coast as well.
I have to clean my vehicles at least every two weeks or they can end up looking just like what you picture.
Can also depend on where the vehicle is parked such as a manufacturing plant that produces corrosives.
Man made chemicals or natural substances like cement and salt.
If you park a vehicle more than 2 days at our local cement plant the paint will be ruined.
This is where I point out there are several major salt manufacturing facilities in Kansas (Hutchinson/Lyons/Independant).

SALT!!!!

My example is living in Sata Cruz California for 12 years it was an on going effort to keep my cars, trucks and motorcycle free of what those first few pictures i this post to look like.
Even now 11 year after moving the remanence of some is still in those hard to get area's on a couple of my stored vehicles from living there.
As for today living 2 hours from Reno Neveda when we travel during the winter when there is snow the first they I do after the trip is rinse the underside of the Mazda down with lots of soapy water. But I can say that if I was not so diligent at rinsing I would have some corrosion from the deicing chemicals they use on the highways to keep the snow controled.

A pure guess, but I'm thinking this car spent a lot of time near the ocean. As others have said, all the aluminum surfaces seem to have a uniform amount of corrosion.

Thanks for the Replies
 

Unfortunately this one was sold out from under me before I could pull the trigger.

For future reference, is that level of corrosion still considered purely cosmetic and nothing to worry about mechanically/electrically?

I'm sure I'll have more questions as I come across more examples. I'm pretty sold on the Gen2 CX-5 after coming across this one.

Thanks again.

It can all pretty much be washed off with a good engine bay cleaning. Even at home with a car wash nozzle.