Rusted Bleeder Screws – Bleeding Brakes

11:13 am Brake Bleeding, DIY, How To Auto Repair


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© Summary: In this auto repair blog, we answer readers questions about brake bleeding, one of which is about frozen bleeder screws. Question: Can you bleed the brakes if ALL the little bleeder valves on each corner are froze? What do I do?  Serious Screwed?  Thanks ya’ll

It’s no surprise, rusty bleeder screws (and other under carriage parts) like you describe usually get rusted from being exposed to salt. In northern states affected by snowy winter conditions come into contact with salt on roads used for de-icing. In ocean front communities like here in Florida a lot of vehicles are exposed to salt when launching boats and jet skis. I’ve worked on my share of rusty brake lines, calipers, wheel cylinders and suspension parts. Working as a mechanic near Tampa in the 80’s and 90’s I could always tell if a car was from up north. I always said if every vehicle I worked on was rusty from salt exposure I would be looking for a new profession!

Loosening Bleeder Screws
To properly bleed the brakes, the bleeder screws will need to be loosened. If the bleeder screws are frozen up (rusted tight or seized) there’s a chance they can be loosened and the calipers or wheel cylinders re-used. First use a penetrating spray like PB Blaster. WD40 is good in many cases but in my experience PB works better for loosening really rusted parts. After several applications and allowing time for the blaster to seep down within the threads, try a six point socket with a ratchet. Twelve point sockets may just round the screw, a wrench due to their angle is more likely to apply uneven force. A ratchet and socket naturally has a 90 degree angle which makes it much easier to apply even force. I prefer to use 1/4″ drive tools because excessive force applied will just cause the screw to break requiring even more work to repair. Lightly tapping on a shallow socket placed on the screw can sometimes vibrate it enough to help loosen it. As a last resort, vise grips or Knipex pliers can be used if the bleeder is too far gone to grip any other way.
Heat Things up a Little

Keep in mind that using a propane or acetylene torch to heat the surrounding area near the bleeder screws can help to loosen them, but can also damage the rubber seals in the caliper or wheel cylinder making it necessary to rebuild or replace them. Back when calipers cost much more years ago, it was worth the extra time to go through this process and then rebuild them afterwards. Depending on the type of vehicle and how much replacement parts are, it still may be worth time and trouble required to rebuild a caliper with a severely rusted bleeder screw. With China supplying such inexpensive parts now (many of them high quality) it’s a good idea to price out the ones that fit the car being worked on before spending a lot of time trying to save the old ones.

Rusted Brake Lines
It seems as though rusted parts are like domino’s. Chances are if the bleeder screw was rusted tight, the brake line will most likely be seized too. If a brake line needs to be replaced, follow it up to the next connection. It is NOT acceptable to use compression fittings on brake lines. Replace the section completely or use double flared connections. It is a common mistake for compression fittings to be used for repairing brake lines. It is illegal for them to be used for brake line repair, although there won’t ever be any police check points looking for them, accidents if found to be caused by a leaky connection could cause legal repercussions for the repair shop that did the repair. In conclusion, replace the entire brake line section or use a double flare kit to make the proper connections.
Question: I’m replacing a leaky rusted brake line on my 2000 Dodge Caravan. Can I buy a pre-bent brake line for my vehicle?
Answer: In my experience, no. Just take whats left of the old line to the parts store to match it up. The fittings are different sizes just as nuts and bolts are. The brake lines themselves are different diameters as well. If you’re taking only the fittings to the parts store be sure to measure the over-all length. A brake line bender will be needed to shape the line to the correct contour. Bending the line without a tool can cause a kink restricting fluid travel.
Question: I broke the bleeder screw off on the right front caliper. Can I replace only one or should I replace them in pairs?
Answer: I always recommend replacing calipers in pairs. Uneven braking can occur since the new one will most likely apply and release faster than an aged caliper. One caliper can be replaced and then the car can be test driven. If the car pulls to one side when the brakes are applied, be prepared to replace the other side as well.
Question: I took my car in for a bargain priced brake job and they told me I need to replace my calipers and rotors. Is this a rip off?
Answer: If you question the shop that you’ve taken your vehicle to, get a second opinion. Many shops pay their mechanics spiffs or bonuses for “up-selling” loss leader brake jobs. I would ask the mechanic to show me the problem with the parts, it could be legitimate. Calipers can have open dust boots split or torn from age or excessive heat. Rotors can be too thin to machine. If you are uncomfortable with their explanation take your car to another shop for a second opinion. Most shops offer free brake inspections.

Also see our related article on master cylinder bench bleeding. Have questions for a brake expert? See our car questions page to find a brake certified specialist now.

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6 Responses
  1. Ken :

    Date: September 30, 2009 @ 2:09 pm

    I have a 1986 F250 and live in MN. Recently had to replace the rear brake line due to rust. Now needing to bleed the brakes, I cannot get the bleeder screws out, and have tried lube, heat, and a combination of this. The truck is very rusty, and only has 47,500 miles on it. I hate to junk it or spend a lot of money on parts. Can I bleed the brakes other than with the screws? I heard a trick of pulsating the brake pedal to bleed air up through the lines? In Distress….

  2. dennisb - Auto Tool Sales :

    Date: October 1, 2009 @ 8:48 am

    Ken, it’s possible you may be able to bleed the brakes by loosening the brake line instead of the bleeder screw. Remember that the air will normally rise to the highest point so it may become trapped if the line connection is lower than that area.

  3. mjlogan2001 :

    Date: October 14, 2009 @ 2:48 am

    You could replace the wheel cylinders in the rear brakes. That’s the part that the brake line threads into and and it houses the bleeder screw. They bolt to the backing plate of the rear drums. They aren’t that hard to replace and pretty inexpensive also. The last one I bought was $8.00. Living up North, I’ve had to do that to three vehicles I’ve owned over the years due to bleeder screws that were rusted and broke off.

  4. Don :

    Date: September 22, 2012 @ 4:15 am

    Dennis, my brake problem questions have been answered by reading the above.very helpful and much appreciated. {ive broken off PLENTY of bleeders in my time} thanks

  5. Don :

    Date: September 22, 2012 @ 4:32 am

    I need to bleed my back brakes since i replaced a rusty broken line. there are 2 bleeder screws on top of the ABS unit. In what instance would one ever bleed air out from these and does the ABS have to be operable?

  6. dennisb - Auto Tool Sales :

    Date: September 22, 2012 @ 8:53 am

    Don, If the system has completely drained it may be necessary to bleed every bleeder on the the vehicle. To answer your question about ABS – the ABS system can have a electronic fault and the brakes can still work OK. But, you would not have the advantage of the added safety that an ABS system provides. However, if you have air in any part of the system, the regular operation of the brakes will be diminished. One of my favorite methods of bleeding the brakes (and hydraulic clutches) is with a vacuum bleeder. Many times the vacuum will pull the air bubbles out very easily. I’ve used them at the reservoir by removing the cap and using my cupped hand with a latex glove on, holding it over where the cap normally goes. Creating a suction there can pull air bubble up and out of the system. You can actually see bubbles rise out of the fluid. The vacuum bleeder also works great to bleed at the screws. Good Luck

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