Hot Metal Smell Coming From Rear of Car

[SpooliWagonMan]

Hi guys my little brother was driving my 2000 V70 XC AWD (now FWD) with 225,000 miles last night and it started making a smell. It was a hot metal smell like cutting steel with a cutoff wheel. It seemed to be coming from the left rear wheel well. I went and picked it up and it drove home without issue, and I smelled the smell. Today I set about diagnosing it. I was sure it was a locked caliper, however, when I jacked the car up, the wheel spun freely. I wrenched the e-brake, wheel was locked: K fine. I went and drove it to see if I could get the smell to come back, and the ride was pleasant and without issue, just like every time I drive a Volvo.

I'm stumped, and I have to go to the dentist now (I'll just take the project cause its like an hour twenty drive) so I'm out of time to play with it.

Does anybody have ideas about what could be happening? is there a typical issue? Where should I look?

Thanks All

[RickHaleParker]

Little brother riding the brake or did not fully disengage the parking brake, glazed the brake pads?
Does little brother tend to brake with the left foot?

[abscate]

Have a good look at the rotor surface on both sides - you have to crawl under with a flashlight (torch in the UK) to see the back side. Look for signs of heat or corrosion. If all is well, it probably is a parking brake issue, and left-on the likely cause.

[tardcart]

Ive had intermittent seized caliper on my p80 up front, I think it was some glitch in the antilock tracks system pressurizing the caliper for traction control since the caliper moved fairly easily, though not like new. It hasn't happened since I replaced them though. If you checked them when cold, its remotely possible the rubber line is swollen shut and the fluid expands when hot, even boiling if its hot enough. when cool the vapor turns to liquid and releasees the pressure.

[SpooliWagonMan]

I would hope he doesn't ride the brakes, I'll ask him and peak under the car tomorrow. Knowing who I got the car from, it probably has the original cat and it throws that code all the time. Could that be smell? I haven't had a car with a stock cat for a while...And never one with such high mileage.

[tardcart]

You know the smell of burning asbestos, its un mistakable. Im not aware of a clogged cat smelling. an overheated one from rich mix smells hot but not the same smell.

[Sommerfeldt]

You know the smell of burning asbestos, its un mistakable.

I hope that's not something you smell on the regular - it's been banned over here for a looooooong time, and unless you intentionally look for them, I'd think asbestos lined brake parts would be unlikely in the US as well?

- S

[abscate]

I think he was generically referring to burned pads, which do make quite a smell, even with the new materials,

[RickHaleParker]

I haven't had a car with a stock cat for a while...And never one with such high mileage.

Don't be quick to blame the cat. It is a common and expensive mistake.
Even with a O2 code, there are lots of things that can trip a O2 code.

[SpooliWagonMan]

Yeah those cats are not cheap, and I'd prefer to leave the exhaust alone anyway. I'm happy to rule that out.

So I talked to my little bro and he drives like I taught him and one foots it, so brake riding is out. As for the rotors, they don't look too hot, but they were like that when I put new pads on (could that be it? I mean no noises or shakes. All seems to function well, but I don't know and need to ask). We've still been whipping around in it, and probably put another 50-80 (city and highway) miles on it in the past two days and no smell since the other night. It seems to have gone away. I'm thinking about pulling the wheels off and checking it out. Anything non-brake related that could make the smell that I should look for?