What did the Dealership do to My Car?

Did they over tighten the E-brake? Does it coast as well as it normally did? Is the ICE air cleaner OK. How strong is the 12V. H

 

first thing I would check is the rear brakes, you said they were adjusted making me think they are drum brakes, and its very easy to over adjust them and make them have too much drag.

second thought would be that if the front pads were sooo worn down that they needed replacing; that when the calipers were fully retracted there was more clearance between the rotors and pads so you had no friciton between them, and now with the new pads obviously having more friction material there is less maybe even no clearance so there could be a slight drag effect that you would definitely feel at slower speeds.

just my 2 cents...from an ASE master tech

 

i would jack it up and make sure all the wheels spin freely. between the fluid flush and rear adjustment, anything is possible i guess.

 

Jack it up is a good plan. Probably e-brake. I don't believe the front pads would be a issue. H

 

On a past car, improper dealership brake system work did cause my front disc pads to drag excessively. It was also sensitive to ambient temperature, triggering in 90F+ heat.

 

This is an Aha! moment for me. The other day I experienced reduced MPG, and that sticky feeling of reduced coasting, and it was in hot (90 F), stop and go conditions at low speeds, so more friction braking was being used. Later, on a cool run with almost no friction braking, the MPG was back to normal at 60+, and the coasting was obviously back to normal. So there seems to be something dragging when hot, and the question is how to narrow it down. If it is the front discs, is there a way to release that friction?

 

Hi Tony. I agree you should jack it up and check for brake drag, but there's one other thing to consider.

When they did the brakes they probably disconnected the 12V battery, so you would have lost the "historical data" that it uses to help calibrate the MPG calculations. I noticed that the Prius's MPG calculations were off for quite a while after my historical data was reset.

The other obvious things to check are tire pressures, oil level and 12 volt battery readings.

 

I see it mentioned but no response
The "e" brake, emergency brake is adjustable as it's a cable, it would have to be quite tight to be engaged when fully released, but I don't see that the adjustment to the rear brakes is mentioned, on the inside of the brake drum is a little rubber plug, it's keeping water out of the brake assembly, when it's removed a star brake adjuster is revealed, the mechanic adjusts the rear brake shoe tension with it and it may have been adjusted to tight.

Oil at the top of the dipstick will also lower mileage, something knocking the front end out of alignment would cause mileage to change, if somebody put gear oil(thick) in the front axle instead of the correct oil, things would be "different"

 

If temperature is affecting brake friction I would suspect that there is some air in the brake lines and they need to be bled. I don't believe the brake fluid itself is affected much by temperature. Air in the brake lines will not only result in "squishy" brakes, but can keep them from fully retracting after a hard brake, leaving them dragging the vehicle.

The OP just had his brake lines flushed, meaning new fluid and hopefully all the air properly purged. It is still easy enought to get air in the brake lines during a brake line flush but I wouldn't expect it.

 

When the rear axle is raised up and the parking brake disengaged, the rear tires should freely spin. You should not hear the rear brake drum rubbing against the brake shoes as it rotates.

The front tires will not spin easily but you can try raising up the front, making the Prius READY, then shifting to N. You have to spin MG2 so there is more inertia to overcome.

 

Thanks for mentioning that Patrick. How to test the front wheels is something that I was wondering about.

If you put the car into "N", do you think that you'd still be able to feel the difference between that inertia plus the bit of friction from the transaxle compared with what would presumably be a slightly rougher feel of a dragging brake pad?

 

Disc brakes are always in light contact with the rotor. Checking excess drag on the front brakes is a little tricky: even in neutral the transmission is going to impose some drag. It's something new for me: having to start up a car to get it into Neutral, haven't done this on our Prius. One quick way to check for front wheel brake drag: feel the front wheels after an extended drive. They shouldn't be more than slightly warm; if they're feeling warm to hot you have excessive drag.

That said, the rear brake, with the parking brake (aka emergency brake) mechanism, is a more likely culprit. Second gen is drum brake I believe? If you can, raise the whole rear, using the central rear jacking point. Or in a pinch just lift one rear corner at a time with the supplied scissor jack.

Apply and then release the parking brake. Then give the wheel a spin. There may be a bit of whisper at one point in the revolution: there's sometimes a point on the pad that makes slight contact. This might happen on one side of the car, and not the other.
If you spin the wheel and it really hangs up at one point, or is hard to even spin, that's too much.

 

i have jacked up my old 04 when the tires were making a funny noise and i didn't know it. check for cv joint problems or bearings, i think it was pretty easy to tell the wheels were spinning freely and the difference between drive train resistance and dragging brake pads.

 

While the rear end is raised you can also try applying the parking brake just one "click", and see what that does. Then 2 clicks, and so on. What's nice to see is free spinning at no clicks, and even at 1 click. Then slight drag at 2, more resistance at 3, and eventually solid lock up.