My soon to be wife got her 2001 volvo v70 t5 last summer, at the time it was great, got 24-26mpg(just like my Volvo does). But since then it has gotten progressively worse and worse. This past week it got 14mpg, and over half of the tank was a 150 mile interstate trip. The worst it has ever gotten, it had been getting 16-18 in the month or so before now.

When we got out of the car after the 150 mile trip you could smell a potent brake smell, and the wife said she had smelled it before when she got out of the car. It seemed to be coming from the driver side front brake.

So today I took it for a short drive(a little over 2 miles), got back, and felt the brakes and none of them were hot. I then jacked up the front of the car and both tires seemed to spin freely.

On the highway it seemed to vibrate some like you would expect if a brake was dragging. It also seemed to pull to the left a little, but not a ton.

Is it possible the brake starts to drag after driving the car for some time, then when it cools down it stops dragging? I plan on taking the car for a longer drive today to see. And I had the local parts store order a new front left caliber since no place seems to have one in stock just encase I need one.

Any help would be appreciated.

 

It's possible the brakes may get tighter w/ use. This usually happens when a brake wheel piston is not fully relaxing when hydraulic presssure is released; corrosion on cylinder wall or piston can cause this action. However, you will have a very hot brake after a short drive 10-15 miles perhaps.

Other possibilities are weak O2 sensor response leading to overly rich mixture, or fuel leaks (leaking fuel lines or injector seals).

good luck

 

Took it for a longer drive(10 miles or so) with some purposely heavy brake use. Got back and while none of the calipers were hot, I could smell it, but this time it seemed worse on one of the rear brakes. I jacked up the whole car, and the back was dragging some times, clear noise different when half the rotor was dragging. And the front seemed a lot harder to turn then after my short 2 mile drive. So am I correct in thinking the master cylinder may be bad?

 

I would first take out the caliper slide pins to see if they have grease and are corroded and pitted. If they are corroded or pitted, I would replaced them. Regardless, I would clean the pins and re-grease them.

 

Well I replace the front pads and calipers, and greased the slide pins. I also did spark plugs and fuel filter. Will see if the mpg improves any. Both front calipers went back in without issue. I didn't do the back brakes just because money is tight right now, but they should probably be done sometime in the near future.

I was amazed how easy the brakes and fuel filter were on a volvo, i had a bad experience replacing an alternator in one so I thought a job like this would be awful, but they were actually really well designed(unlike honda's hub over rotor brakes and impossible to reach fuel filter).

I know the throttle body is starting to get worn out, but its a real time consuming and expensive job, so I am trying to put that off till I have more spare money. But I don't see that causing this much loss in fuel mileage.

 

I've had dragging brakes & mushy brakes (2 different times / 2 different cars) that I think were the result of corroded shims behind the brake pads. So those are (probably) new with the new pads? You'll probably keep an eye out for dragging brakes now.

 

Well it has gotten 23mpg since replacing the brakes, fuel filter, and spark plugs. The wife says it seems to drive a lot better. Not sure exactly what the problem was, or if it was a combination of all three.

Now I just gotta track down a good used replacement throttle body(new from the dealer they are $860), and then install it and get it towed to the dealer to pay $85 for them to have it programmed to work. fun times.