Rebuilt Calipers, how much bleeding?

[Ara T.]

I installed rebuilt front calipers (both of them) on my 85 300D W123 tonight with my buddy. The old ones were dragging so I decided to just get some rebuilt Bendixes from brakewarehouse.com

The old calipers came off surprisingly easily, I didn't even really need a breaker bar, just all my strength on a 3/8 ratchet. Anyway I took the speedbleeders off my old ones and installed them onto the new ones and we used up a whole bottle of Valvoline DOT4 brake fluid getting the air out of the brake lines, and the brakes still didn't work very well... they go to the floor and are very slow to stop the car. Is there something I'm missing here? I made sure all the brake line unions were tightened up and all, do I have to bleed the rear brakes even though we didn't touch those brake lines or calipers? Anybody who has done a pair of calipers, lemme know how much brake fluid it took thanks

Ara

[stcbenz83]

im not sure what your problem is, but when i did mine it took maybe half a bottle or 3/4 of a bottle, and trust me, there was ALOT of air in them due to a bad master clutch cylender and a bad caliper

[Hit Man X]

I'd consider flushing the rest of the system to verify there is no air in there. A bad MS can cause all sorts of problems... my SD has one.

Also, after using one of those pressure bleeders I will NEVER go back to the old way of pumping to bleed. The pressure one is WELL worth the $50.

[Ara T.]

Hm. Well I replaced the master cylinder 6 months ago I believe it was. The speedbleeders I am talking of are the brake bleeder valves with the check valve in them that lets fluid out but doesnt allow air to be sucked back in.

[Hit Man X]

I've used speedbleeders, this pressure unit is still better yet. You can let it flush and have a beer.

Pedal to the floor is a bad MS or air...

[t walgamuth]

if the pedal was fine before installing the calipers, then you have not achieved perfect bleeding yet.

the proceedure has to be done correctly. the old fashioned two person way is like this: first be sure you have the mc res full, and check frequently as it will allow more air into the system if the rear res gets empty on you. the rear is mentioned because it is smaller and easy to not notice being dry.

the inside person pumps brake inside car til he feels some pedal coming. then holds pedal against pressure. person on the bleeder opens bleeder and allows fluid to come (out with clear plastic on nipple. put fluid into jar.) person pushes pedal to floor but not as hard as possible just there and holds it there while outsider screws bleeder back in. after bleeder is seated inside person pumps up pedal again. and this is all repeated til no bubbles come out of bleeder.... and you get a nice firm pedal.

any deviation in this process will allow air back into the system.

always bleed the wheel farthest away from the mc first.

if you dont know the age of the fluid or it is known to be more than a couple years old, this is a good time to purge it all and get fresh into the system. it gets contaminated with rubber particals dirt and moisture.

good luck

tom w

[tangofox007]

Originally Posted by Ara T.

we used up a whole bottle of Valvoline DOT4 brake fluid getting the air out of the brake lines, and the brakes still didn't work very well... they go to the floor and are very slow to stop the car. Is there something I'm missing here? Ara

Are your bleeder valves on the top of the calipers? Sometimes folks install the calipers on the wrong side of the vehicle, so that the bleeders wind up on the bottom. That makes bleeding difficult.

[t walgamuth]

yes more or less. it is a thing about 1/4" diameter that sticks out maybe 3/4" from the caliper with a rubber turban looking thing that covers the end to keep dirt out. there is a fitting for a wrench about 8 mm or 10mm.

when first loostening a bleeder, first spray with wd 40 or pb blaster, then put your wrench on and wiggle it a bit. they often are rusty and they are hollow so they will break off easier than a bolt same size.

good luck

tom w

[Matt L]

Make sure that your speed-bleeders are sealed at the threads. Since they're reused, check them carefully. Air leaking in at the threads will make them useless.

I agree with Hit Man about using pressure. It works much faster.

[t walgamuth]

personally i have tried power bleeders and for me they aren't worth the trouble. and i was never able to bleed successfully with a mitivac.

i would like to try some of the check valved bleeders.

tom w

[janko]

in the past working alone i would gravity bleed. open farthest port and let gravity proceed. then on to the next farthest. anyone other than i have luck with this proceedure?

[sokoloff]

I don't consider a MitiVac a power bleeder. The one I have is a Speedibleed, http://www.speedibleed.com/. It is a pressure bleeder and a Mercedes, VW and other European cars with the same screw on cap is soooo easy and virtually idiot proof. It's not quite as easy on other models, but I have used its adapters to do a Honda, a Ford and a GM and once set up properly, they all worked, but Mercedes is so easy with it. It fits my '59, my '83 and my '99 perfectly since they all use the same cap.

Len

[glenmore]

Originally Posted by Ara T.

Hm. Well I replaced the master cylinder 6 months ago I believe it was. The speedbleeders I am talking of are the brake bleeder valves with the check valve in them that lets fluid out but doesnt allow air to be sucked back in.

I have these speedbleeders on my car but in hindsight the powerbleeder mentioned above sounds better particularly if you're keeping up with several cars. I've noticed that a couple of my bleeders are slightly loose so I used a little plumbing teflon tape to snug them up. I just put on new brake hoses and also flushed the fluid. I noticed that the bleeders need to be loosened just a crack. Anymore and I got air in the system.

glenmore
1991 300CE
2000 C280
1990 LS400

[P.E.Haiges]

janko,

I have also use gravity bleeding and the brake system worked well for years after it was done. No problems at all.

Gravity bleeding works as long as there as there is enough flow to push out all the air. Though, if there is a brake line with some resistance to flow, gravity bleeding may not work.

As long as U get all the air out, it doesn't matter what method is used.

P E H