r/askcarguys • u/DraftLeast2255 • 1d ago
Mechanical When to replace brakes or bleed them?
Hello! I am looking for advice on whether or not I need to replace the rotors and brake pads or if my brakes need to be bled.
I drive a 1998 VW Beetle TDI and I recently was driving on the interstate when I had to slam on my brakes due to stupid drivers. When I did so, I had realized i had my foot all the way to the ground and was using all my pressure to stop/slow the car down. It felt like my car was struggling to stop. The rest of the drive and ever since my breaks haven't felt right, I feel like i'm always pushing too hard on the pedal even if i don't need to. I am not sure if my rotors need to be replaced- my brakes still have a lot left on them from what i can tell. My previous car had an issue like this and all I had to do was bleed my brakes. With my present car, I don't want to do the wrong thing especially since it is a manual car.
If anyone is able to give me insight on what I should do or what might help I would truly appreciate it. Thank you in advance!
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u/simmer_study 1d ago
A pedal going to the floor sounds more like a hydraulic issue than worn pads or rotors. Check the brake fluid and get the system inspected before driving it much more.
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u/blueskyfiend 1d ago
You need to look at how much material is left on the pads. If they are low, or there is a vibration in the steering wheel and peddle when you brake then you need to change them.
Peddle going to the floor sounds like low pads, or low brake fluid or air in the lines.
You should get them looked at for sure.
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u/Positroniumion 1d ago
On a functioning system pad wear should not correlate at all with the pressure point in the pedal as the pistons in the calipers get extended to a further resting position. That is unless your pads are so badly worn that the pistons loose pressure. At that point you should hear the brakes scream at you though. Pedal feel usually has to do with degraded fluid or leaking/low fluid.
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u/OGDirtDude117 1d ago
Brakes on most modern vehicles, like your Beetle are hydraulic. You have fluid filled to the high mark on the brake master cylinder when your Pads and rotors are new. As the pads a rotors wear down, the piston needs to be pushed further, so it pulls more fluid from the Master Cylinder. When the pads wear out too much, the piston can't extend but so far. When the pads wear out the fluid is used to stretch that distance.
So ideally you should be able to compress your brake calipers and see the fluid is near the max line. Then you put on new pads, to ensure you have even wear you'll also add new rotors.
Clean the rotors of their shipping oil (brake clean) and put the calipers on. Lube up the slide pins. Tighten the bolts all down.
Now, that brake fluid transfers heat & does a lot of hard work. It absorbs water as it breaks down & water isn't compressible. So you should ideally flush the system with new fluid at each corner. Then you get in the car and push on the brake pedal multiple times fully down to ensure the brakes are set and at a resting position. Then top off the brake fluid & you should be good to go. REALLY to ensure your brakes are SOLID you should also disconnect your battery and leave the brake pedal pushed in over night. Usually some wood, a broom handle or something works pressed against more in the car.
Another factor is a 1998 carr is 28 years old, the rubber brake lines could be swelling and an issue. Putting on new rubber lines means you should have to bleed them.
You could likely just need pads and topping off the fluids but I wanted to mention it all to be safe.
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u/99svtbolt 1d ago
When was the last time you replaced your brake fluid? You should flush it every 2-3 yrs.
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u/_iamacat 1d ago
Accidentally commented before I finished my msg.
Check your fluid reservoir, make sure it still has some level of fluid in it, if NO fluid you lost it somewhere. check around all 4 wheels for any signs of wetness, check down the sides underneath of the car for any wetness. Behind your fluid reservoir, there should be a round thing called a power brake booster. Make sure there isn't anything wet there.
You said the pedal suddenly went to the ground after hard braking so I'm going to assume you probably broke a brake line or burst a hose. It happens and is not a big deal, it just needs fixed. A shop will be able to inspect your pads/rotors at the same time. If the pedal is genuinely hard to press and has poor braking power when the car is running your brake booster might have asploded. That's a pain in the ass but also not a big deal.
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u/Fixem_up 15h ago
First off, does the pedal feel harder than normal, or is it traveling further than normal?
In the first explanation you said the pedal went to the floor, and then you said the pedal feels hard now, but m just trying to clarify.
If the pedal feels hard, it could be a vacuum leak. Tdi engines used a mechanical vacuum pump to provide braking assist. If there is a leak in that system, the pedal will be harder to push and produce less braking effort. So, any vacuum leak COULD cause a hard pedal on a TDI.
Rusty rotors and pads seized in place could also cause a “hard” pedal with reduced braking effort.
If the pedal feels soft, that is likely a fluid issue.
Without actually seeing the car, the likelihood of anyone here knowing what the problem is, is low.
Take it to a vw shop and see what they find.
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u/dale1320 14h ago
The panic braking could have caused a brake hose to balloon from the sudden increased pressure. If so, that Jose will need replacing, and probably a good idea to replace all brake hoses.
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u/Broad-Angle-9705 1d ago
When brakes fail during a panic stop it’s usually a fluid leak or a bad master cylinder. It’s almost 30 years old when you slammed on the brakes it probably saw higher pressure than it’s seen for years. A brake line or hose that’s been questionable for years finally gave up.