98LX Sedan Coolant Flush/Front Brake Pads

[mundy5]

I had a couple of questions about 3 maintenance procedures.

I downloaded the 96 Factory Service Manual and it gives directions that are different than what I saw in the Chilton's manual. So please help me by clarifying my questions.

1. When doing a coolant flush, the FSM says to a) open the drain plug b) remove the drain bolt from the cylinder block c) remove and drain the reservoir. Then to refill, you simply reverse the flush.

the Chilton's manual skipped the drain bolt but instead when refilling said something about a bleeder screw in the thermostat housing.

Which one is right? Why doesn't the FSM not talk about the bleeder screw?

2. When replacing the front brake pads, the FSM says nothing about taking some of the brake fluid out of the master cylinder while the Chilton's manual explicitly states that one needs to remove at least half the brake fluid before replacing the pads.

Which one is right? Can I change the front brake pads without removing some of the brake fluid?

Lastly, when replacing the brake fluid, does one first bleed all the old fluid and then fill the new fluid into the master cylinder and bleed again until all the air is out? Or is there an easier way to replace the brake fluid? Thanks in advance for all your answers.

[snowball1288]

first i dont claim to be an expert by any means but:
1) to drain the coolant i just pull out the drain plug under the radiator and let it all flow out. make sure your climate control temp knob is on hot so the coolant there is allowed to come out too. drain the overflow resevour and then i close the plug and add new coolant...

2) what happens when you change pads is that the new pads have more friction material on them, so they have to be pushed back into the caliper's cylinders a little to get the extra clearance when you install them. i just use a big C-clamp to do this. However, when you push those cylinders back, they push back the fluid as well which raises the level in the master cylider resevour. if you dont remove fluid, it might overflow from the resevour and brake fluid eats through paint and is nasty stuff. As the pads wear, the friction material gets thinner and the pads automatically advance closer to the disc to compensate. this lowers the resevour fluid level gradually, so thats why you should check it periodically and add more if needed. sometimes everything just works out and you dont have to worry about it because they "fill" line on the resevour is far from the top so theres extra space. anyhow... just watch the fluid level carefully as you work and after you finish.

3) for bleeding, what i did was i bought a bleeder kit which had a small hand pump which i used to remove all the fluid from the main resevour. Then i simply opened up the bleeder screws and pumped a few times to completely flush the lines clear. Then i closed everything, added fluid to the reseviour and started bleeding one brake at a time. Alternatively if you dont have a hand pump, you could just open a bleeder screw and pump the brake until all the fluid comes out that side. same thing. my manual says to simply drain the reseviour with a pump and then bleed out the fluid at each corner until you see the new fresh fluid coming out instead of the old fluid, which i guess would be faster than completely draining and refilling and would introduce much less air into the lines, but i can never tell when the old fluid is gone and the new fluid starts coming out. i just get all the old fluid out of the entire system, get new fluid in the resevour, and then worry about bleeding.

good luck on your car. its not too hard... kinda fun actually.

anyhow, i'll stop before i wind up writing a book here. anyone else do it differently?

[mundy5]

Thanks Snowball. I guess Chiltons just goes the extra mile and gives more precautions than the FSM.

I understand what happens with the brake pad replacement though I wonder why the FSM does not say anything about draining some fluid first. Maybe it's so obvious that they didn't even mention it.

Anyway, both of these fluids are long overdue for a change so I'll be doing it once the weather gets a little warmer.

I would appreciate any other folks who have done these fluid changes before.

btw, where do you give the used fluids? Do you call a local garage?

[jclark]

There's a big difference between changing pads and a brake job.
The calipers need to be cleaned out every so often.
They build up with dirt and water and eventually start to not
release easily, and can even sieze up.
This is the main reason pads wear quicker on older cars.
I usually take the piston out of the calapers and clean it out.
You wouldn't believe the dirt and water that usually comes out.
Parts stores sell a rebuid kit, it's the dust boot and O ring.,
I usually reuse the old one if not torn.
If it takes a lot of force to push the piston in when installing new pads
then it needs to be cleaned. It is difficult to reassembe if you don't
know how, it's a little tricky and hard to explain so I usually recommend
when others do a brake job to open the bleeder, turn the caliper
upside down and squeese the piston in forcing the fluid out, into a pan.
(And note how dirty it is) Generally you'll get most of it that way.
Also don't forget to make sure the rods are well greased for
the caliper to slide easily.

[mundy5]

Thanks Jim for your helpful post. I'm new to this and basically my situation is that I had a brake job done by Firestone about 2 years ago in which they replaced both the pads and the disc. I had let it wear down beyond the service limit and that was my mistake.

Is it safe to presume that these guys also cleaned my calipers etc? Or should I go under the assumption that they simply replaced the pads and the disc but didn't clean the calipers?

[jclark]

No one ever cleans the calipers.
They generally only replace them when they start siezing up.
The labor of cleaning them properly would probably be more than
buying new ones.
It's the most neglected part of brakes, but now calipers have gotten
cheap enough that on a total brake job they just replace them.
If you keep them clean you'll never have to replace them,
and your pads will last longer.
It's a time issue.

[mundy5]

Thanks Jim. I would certainly want to clean the calipers the next time I replace the pads. I have download the factory service manual on my year and so I think I have the necessary diagrams etc to make heads or tails out of disassembling and reassembling the calipers. My only question is how do you clean them? Do you use a particular type of solution? Or do you simply clean them off with a shop towel? Are there any special tools needed for the job? My car is now 9 yrs old and so I would say that it definitely classifies as needing to get the calipers cleaned the next time I change the pads.

I had a brake job done by Firestone 4/13/04 and it was the first since I purchased the car in 12/97. I hope that it will last a bit longer until the summer so that I can take care of the cleaning and replacing the pads then.

I think that most places don't clean the calipers anymore and I wouldn't be surprised if all Firestone did was simply replace the pads and charged me a ton of money for it. I'll take a look at the work order to see if they cleaned up the calipers or not.

[jclark]

Once you pop the piston out it's just a matter of emptying the
cavity and sludge out. And maybe wiping out with a paper towel.
This can be done by pushing the brake pedal in small increments untill
it forces the piston out. Doing it that way requires doing one side at a time.
I usually disconnect the calliper and place it in a pan and use air into
the bleeder valve opening. caution here, it takes little air psi and you need a
thin wood block positioned to keep the piston from slamming out into the calliper.
Start out with low air, like 5psi and build up. (It can pop out fast.) Be careful.
Remove the "O" ring and wipe it off. Do not use any cleaners on it.
Some, like mineral spirits will swell it up.
Wipe the piston off and check for pitting, and rust. It has to be smooth,
if not replace it. (or get a rebuilt caliper) It went to long.
When reassembling, install "O" ring, wipe brake fluid on it and the piston,
put dust boot on piston first, leaving enough overhang so you can tuck the
boot back into the caliper groove and seat it,
Then push piston squarely home. It should push in by hand.
There's a little bit of a trick to this, but once you do it, it's not bad.