Frozen Calipers? Warped Rotors?

4

415runner562

New member
I have been noticing something wrong with my 4Runner. A couple of things:

-Everytime I brake, it pulsates as I slow down, more so when it is just about to reach a full stop.

-My gas mileage per tank has gone from ~380 to ~280

I live in the LA area, so it barely gets cold here. I highly doubt it's the gas.

Do I have frozen calipers? Anyone in SoCal EVER have that happen? I haven't taken the 4Runner to the snow yet (other than my move to SoCal along the 5). Any help would be appreciated!
 
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We will assume that you haven't done a brake job yet. Mileage??
Quite possible, common issue on 4th gen. I had the rotors turned and replaced pads at under 50,000 to fix pulsation. Replaced pads and rotors at 110,000 and just replaced a caliper at 120,000 which was frozen.
 
Might just be rotors, but that gas mileage drop might be telling you there's a frozen caliper as well.


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Since you meitioned a reduction in gas mileage I would start by inspecting both front calipers to make sure they are not frozen. The pulsating could be due to warped front rotors and is usually the main culprit based on what you are describing.
 
It could be either. Especially with the 4runner caliper design.

On most vehicles....there's just one piston per caliper. On the 4runner there's 4 pistons. If one of the pistons get stuck....it causes uneven braking. This situation doesn't arise if you have just one piston.

Warped rotors are another cause of this problem.

First thing I'd do is check the calipers. Remove the caliper...and see how difficult it is to push the pistons back in. If one or more are real difficult...then I'd consider replacing the calipers. After they're replaced...of you still have the problem..then replace the rotors. Make sure you have a big hammer to remove those rotors.
 
Yea. If one piston is dragging or stuck, you might not even notice it until you pull the pads and see uneven wear.

Anyway, the easiest thing to do is pull the tires...
 
At the moment, I have about 116,500 miles.

I changed all four brake pads at or around 108k miles.

In the event that the calipers are frozen, how would you rate the difficulty of the job? How much time do I need to put aside to do it? Do you recommend any calipers for me to buy?

In the event that the rotors are indeed warped, should I turn them, or replace them? If you recommend replacing them, what brand of rotors should I buy?

My rotors have never been turned.
 
Job Difficulty?

On a scale of 1-10. 1 being pumping gas and 10 being a complete vehicle overhaul, including engine and tranny. I say a 3. It requires some tools and a bit of arm strength.

It is a very good, beginner job to work into cars. Buy a repair manual like a Haynes, and it will have some pretty good step by steps.


As for rotors. If they are warped, trash em. Don't bother turning. Once warped, a rotor gets funky and even if it was able to be turned it would just wear weird. Its heat dissipation properties are knocked off now and it will heat and cool oddly.



A tip: If you don't care about brake pads much, you can get loaded calipers that will have your standard brake pad in it. May not be the quietest ceramic pad, but with a 4 wheel disc brake system with 4 calipers per tire, it will stop just fine. Ton's of people use loaded calipers because it is easy.
 
It's very easy.

There are only two bolts holding the caliper in place. Remove those bolts and disconnect the brake line....then remove the caliper. The only problem is those bolts may be frozen on and you need a big breaker bar with a pipe extension.
 
Same gas mileage problem...

My gas mileage has dropped about like the OP's. I have not had any pulsating while breaking. It was about time for new pads anyway and I wanted to check the calipers.

I changed the front pads this past weekend. The calipers were not frozen and moved very freely. 125k miles with the original front pads. The backs still have about half the pad left.

I changed the spark plugs at 120k. V8 still runs like a top, its just sucking the gas now.

Of course the mileage still has me concerned.I did have the timing belt/water pump changed last month.

Anyone have any ideas on what else I could check?

Sorry for the thread jack. Seemed to be a very similar situation....
 
today said:
My gas mileage has dropped about like the OP's. I have not had any pulsating while breaking. It was about time for new pads anyway and I wanted to check the calipers.

I changed the front pads this past weekend. The calipers were not frozen and moved very freely. 125k miles with the original front pads. The backs still have about half the pad left.

I changed the spark plugs at 120k. V8 still runs like a top, its just sucking the gas now.

Of course the mileage still has me concerned.I did have the timing belt/water pump changed last month.

Anyone have any ideas on what else I could check?

Sorry for the thread jack. Seemed to be a very similar situation....
Click to expand...

For you, check the plugs for correct gap, O2 sensors and catalytic converter(s). There's a number of culprits for poor fuel mileage and some of the basic maintenance items can be part of the issue; especially at 100K+ miles.
 
Brakes

I experianced similar problems with my 4runner, After i purchased my vehicle and putting some miles on it i began having brake issues at 100k, my t4r was a mid west vehicle in an area that salted roads. Needless to say my presumed quick and easy brake job turned into a nightmare. Each and every caliper had at least 1 siezed piston. I bought all new calipers, rotors, and pads from my local NAPA spending $800-$900 on everything and my brakes are now good to go! Lesson learned, don't purchase used vehicles from areas that salted the roads =/
If you have a siezed piston i imagine your brakes will get very hot as mine did. Ever drive with the E-Brake on? similar situation (except the 4r shares a main disc, e brake drum style rear brake)
Something else worth checking... I know this might sound rediculous as far as gas mileage goes, check your air filter.. i've noticed huge changes in mileage and the problem was my air filter was being TOO restrictive. Best of luck!
 
Brakes

Also! if you have a Les Schwab locally, they typically do "Free Brake Inspections" i have taken advantage of this just to get a diagnosis to problems and then fix it myself! Super quick and best of all, FREE
 
Ok some good and some bad information here...

A pulsating brake pedal is definitely a sign that one or more rotors are warped. the cause may or may not be seized calipers. Could just be from driving too fast and braking late or from the pads themselves being stuck in the calipers, often from lack of maintenance.

A warped rotor can Absolutely be turned (machined) without any ill consequences. I know because I turn 50-60 sets a year, with maybe 5-6 of those having recurring issues. Often the younger guys seem to have the most comebacks, hint hint. If you bring the rotors in it should cost about 20$ each. and you'll still have oem rotors.

If you do need new calipers, one tip for the future. I recommend to all my clients that they do a full brake maintenance at least twice a year (up here in the great white during tire change season). On calipers this means making sure the pads move freely and pushing all the pistons all they way in. this ensure the pistons move freely and lubricates them with brake fluid. your pads will wear more evenly and you'll have way better braking.


Good luck Jesse
 
For you, check the plugs for correct gap, O2 sensors and catalytic converter(s).
Click to expand...

Plugs that are gaped incorrectly show up in acceleration. If acceleration is fine (especially at the higher RPM's) then the plugs and gaps should be fine.

Any problem with the O2 sensors or catalytic converter is going to be detected by the OBD-II computer. And contrary to what people selling this products will tell you....O2 sensors and converters rarely fail.

The BIGGEST cause of poor gas mileage is driving habits. Quick jack rabbit starts and high speeds can have a drastic affect on gas mileage.
 
I got the same issue, but half the time when I start from a light again, there is a click, like brakes let go late.
 
Just wanted to update:

-I seafoamed my 4Runner, using two cans. I used 1/3 in the crankcase, 1/3 in the fuel tank, and 1/3 in the VSV valve.
-I cleaned the MAF sensor and throttle body.

I was able to regain some of the MPG that I had lost, going from ~280 back to ~360.

My calipers are fine.

My front rotors, however, are warped. I had a mechanic check them out. The mechanic mentioned that the front rotors and front brake pads should be changed together. Is this true?

My question is this: Where should I buy a pair of calipers? What brand do you recommend? I was told that the rotors are 12.6". If you can, please tell me a model number so that I can look into them.

As for pads, should I stick with OEM? That is what I have all around.

Thanks again!
 
From what I read previously, sr5 and limited rotors are 12.6", and sport models are 13.3"I think. I should clean those few things.
 
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