2014 with 185k (previous owner uber car). last weekend drove up to Tahoe (5h drive 7k passes) and got only 37mpg going up (instead of 42+), but got normal 50mpg coming back. During the 8+ drives there, I managed to smell brake pads 3 times when I stopped including when driving up the mountain - so clearly some brake drag.... but went outside and never could smell what wheel it was. Yesterday drove RT to Berkeley (1.5h each) and got similar 42 and 49mph when they should be the same... but no smell. something is affecting my mileage. I now carry a heat gun to see what wheel might be occasionally dragging, but have not found the issue... I did a brake bleed/flush about a year ago (not very dirty) and as far as I know pads have never been changed (185k) but I recall seeing plenty left (have to look again). as far as I know the brake pin have never been re-lubed - could this be the issue ?
it's possible, but you should certainly jack her up and see if all the wheels spin freely, then pull them and inspect the brakes thoroughly, and lube the pins. some say you can feel a hot wheel by hand after a good drive, idk.
Well you can try and remove all the wheels and look at the brake pads. If any of them look more worn, there will be your answer. I mean, you're due for a brake inspection right?
Sometimes you need a more sensitive test to identify some less-obvious drag. There's such a test described here.
Good idea for the rears. With the fronts you can't do that though, due to linkage to the transaxle and so on. But yeah check the rears. More info in my signature.
I would check that pads can slide in brackets without excess force. If not give em file. I just did the same on my Honda rear brakes. They had perfectly moving pins but pads were practically stuck. Not obvious drag but drag i could easily notice (i am allergic to brake drag). Discs had brake pad witness marks all over them from parking. They disappeared after the file job I often make pads so loose they almost have gap but cannot recommend this to others. It’s also good to every now and then brake bit stronger when reversing
In Prius calipers, often the "fitting kit" is responsible: the set of little springy clips that sit in channels of the caliper brackets and hold the ears of the pads. Those come with a dry, Teflon-like coating (any grease on them would only be a grit magnet), and the coating wears off eventually, and later, rust sets in. Fitting kits are $16 or so if I remember right, one kit (front or rear) has everything to do both front or both rear calipers. They are nearly the only things I change sometimes at Prius brake inspections. Stay on top of inspections and everything else just lasts and lasts and lasts.
Have not checked Prius clips but i can imagine. Clips are usually PITA. People spend so much effort on pins. They impact to outer pad only whereas pad fitting impact both pads
Clearly the brake pads are not releasing completely so I would relube the pins. Or the bore on one of the calipers is worn and not retracting. A brake investigation is warranted. The Permatex high temp brake lube. Glad your keeping an eye on them as a bstuck calipers can burn your car to the ground I got one on a car I had driving fine all of a sudden the car started pulling hard to the right. I smelled burning so pulled over fast as I could. The rim was so hot I prayed the tire didn’t catch fire.
I'd be curious if he found out what it was as this is an old post. It may not even be the brakes at all, a lot of things can smell similar.
i once had disc so hot it was glowing in the dark. One friendy guy overtook me, then slowed down and opened window shouting me: ”your disc is red hot glowing, pull over for safety sake”.
A dragging pad gets so freakin' hot so fast. Probably main reason you see cars on fire on the side of the road. Once the tire catches on fire the car is done. Most of the time its a dry slider pin or the bore of the caliper is bad. I was lucky the tire on my car didn't catch on fire it was hissing lol..... That was a tow home. Crown Vic.