1990 300E Brake Bleeding Issue
06-07-2015, 06:09 PM
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1990 300E
1990 300E Brake Bleeding Issue
Hi there,
I'm new to these forums and thought this to be the best place to post about the problems I'm having bleeding the brake fluid from the 1990 300E. I noticed the brakes feeling a bit more mushy than they normally are on the W124 cars, so I checked brake fluid. It was quite dark and my dad decided it should probably be replaced. After all, it cant hurt can it?
So we tried traditional methods without reading the manual (I trusted my dad's judgement). We would loosen a bleed port on 1 wheel and pump the brakes. This worked at first until nothing started to come out. We thought the fluid was being suck "back and forth" so to speak, so we replaced the master cylinder to see if it was bad. This was not the problem.
We read the manual and followed the bleeding instructions exactly, and no fluid ever came out. Our reservoir was full and the fluid level was not dropping. It sounded like a bunch of air bubbles were coming out whenever the brakes were pumped.
Next, we tried buying a spare fluid reservoir cap and fashioning a tire valve onto it. We regulated an air compressor to 3-5 psi and used that to try and push the fluid out that way. The pressure system worked and the air bubble sound continued, yet no fluid ever came out, and the fluid level, again, never dropped!
This is where we give up. We don't know what else to check except maybe our ABS system is bad? When pumping using out pressure bleeder (air compressor @3-5 PSI), I could here what sounded like air moving through the ABS system and the tubes leading out of the master cylinder.
Any help on this? Thanks.
Caleb
I'm new to these forums and thought this to be the best place to post about the problems I'm having bleeding the brake fluid from the 1990 300E. I noticed the brakes feeling a bit more mushy than they normally are on the W124 cars, so I checked brake fluid. It was quite dark and my dad decided it should probably be replaced. After all, it cant hurt can it?
So we tried traditional methods without reading the manual (I trusted my dad's judgement). We would loosen a bleed port on 1 wheel and pump the brakes. This worked at first until nothing started to come out. We thought the fluid was being suck "back and forth" so to speak, so we replaced the master cylinder to see if it was bad. This was not the problem.
We read the manual and followed the bleeding instructions exactly, and no fluid ever came out. Our reservoir was full and the fluid level was not dropping. It sounded like a bunch of air bubbles were coming out whenever the brakes were pumped.
Next, we tried buying a spare fluid reservoir cap and fashioning a tire valve onto it. We regulated an air compressor to 3-5 psi and used that to try and push the fluid out that way. The pressure system worked and the air bubble sound continued, yet no fluid ever came out, and the fluid level, again, never dropped!
This is where we give up. We don't know what else to check except maybe our ABS system is bad? When pumping using out pressure bleeder (air compressor @3-5 PSI), I could here what sounded like air moving through the ABS system and the tubes leading out of the master cylinder.
Any help on this? Thanks.
Caleb
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