break fluid raising - e220 2007year
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break fluid raising - e220 2007year
It's my Mercedes e220 cdi 2007 year.
When I bought the car a year ago, I noticed that the brake fluid in the reservoir was overflowing (over the maximum level), the seller didn't tell me anything. I drove the car completely normally until July when the rear right wheel started to heat up (lock up), then the brake calipers were repaired, new brake pads were put in and the brake fluid was changed, and new fluid was put in.
Later during the summer, at the end of August and September, I noticed that the brake fluid level had again increased in the reservoir above the maximum level, but I had no other symptoms.
Until one day in late November (approximately 9000km driven from july to november), when the same wheel started to heat up and lock up again, I replaced the brake hose and since that didn't solve the problem, I replaced the ABR control unit. I bought a used one, and I checked through the contact at the authorized service, using the vin numbers, that it matched my car. Then the system was re-bleeded and the car worked without any problems for about a month and a half (approximately 4000km driven) when one day after a long drive and heavy braking I noticed that the wheel was getting hot again.
Since then I haven't driven the car much but I have noticed that the wheel didn't lock up, it didn't get hot after those drives..which means that it happens periodically, whether after heavy braking or just on its own, I don't know..What I have noticed again is that the level of break fluid in the reservoir is increasing, which is very strange to me.
Has anyone had a similar problem?
When I bought the car a year ago, I noticed that the brake fluid in the reservoir was overflowing (over the maximum level), the seller didn't tell me anything. I drove the car completely normally until July when the rear right wheel started to heat up (lock up), then the brake calipers were repaired, new brake pads were put in and the brake fluid was changed, and new fluid was put in.
Later during the summer, at the end of August and September, I noticed that the brake fluid level had again increased in the reservoir above the maximum level, but I had no other symptoms.
Until one day in late November (approximately 9000km driven from july to november), when the same wheel started to heat up and lock up again, I replaced the brake hose and since that didn't solve the problem, I replaced the ABR control unit. I bought a used one, and I checked through the contact at the authorized service, using the vin numbers, that it matched my car. Then the system was re-bleeded and the car worked without any problems for about a month and a half (approximately 4000km driven) when one day after a long drive and heavy braking I noticed that the wheel was getting hot again.
Since then I haven't driven the car much but I have noticed that the wheel didn't lock up, it didn't get hot after those drives..which means that it happens periodically, whether after heavy braking or just on its own, I don't know..What I have noticed again is that the level of break fluid in the reservoir is increasing, which is very strange to me.
Has anyone had a similar problem?
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
Sounds like a faulty master cylinder and potentially a collapsed brake line somewhere. The seals in the master might be worn and allowing fluid back into the reservoir.
I wouldn't be surprised if you had more than 1 problem. Next time it locks up, loosen the bleeder valve at the caliper and see if the piston returns to its unpressurised position. If it doesn't then you've got a caliper issue. If no fluid comes out, probably a collapsed hose or master cylinder problem. Hope that gives you some clues.
Keep in mind these cars are getting older and corroded brake lines will.become more prevalent.
I wouldn't be surprised if you had more than 1 problem. Next time it locks up, loosen the bleeder valve at the caliper and see if the piston returns to its unpressurised position. If it doesn't then you've got a caliper issue. If no fluid comes out, probably a collapsed hose or master cylinder problem. Hope that gives you some clues.
Keep in mind these cars are getting older and corroded brake lines will.become more prevalent.
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2010 ML550 VIN WDC1641722A564750, 2010 B180
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I still haven't solved the problem.
Since I posted, I've done the following:
I replaced the brake caliper on the rear right wheel on my own initiative (i installed a used one), which didn't solve the problem. The wheel continued to lock up and heat up occasionally.
I checked the brake line, it looks like new along the entire length of the vehicle, undamaged, except for a small section in the rear of the car where there is visible corrosion for a length of 5cm, but I would say that it's only external corrosion, so that the line can't be destroyed from the inside.
I used a compressor to blow out from the inside the entire lines for both the left and right rear wheels. If they were clogged with something, that would come out.
I took other ABR unit from a friend (to make sure it wasn't the problem), installed it and bleeded breaks.
While driving after all this was done, I noticed that both the rear left and rear right wheels are now locking up intermittently, at different times. I don't know if it has to do with hard braking or not. But I drove the car with one hard brake to a stop, continued driving for about 2-3km when I stopped and touched the wheels, the rear left was hot and the rear right was cold. I jacked up the wheels and while the car was on, transmission in N, and tried turning both by hands, they turned without resistance. I continued driving further for about 5km with one hard brake and when I stopped the rear left wheel was cold and the rear right was very hot. I jacked up again and both turned by hand without any problems.
I don't know what else to do, what could be the problem.
I don't know if it has anything to do with this, but I noticed during the last bleed break a shrilling sound (louder than it would normally be) after unscrewing the air to let out. That sound occurred in both the rear right and rear left wheels. Previously before all this (when I was changing ABR unit in November), such a sound was only heard in the rear right wheel.
Since I posted, I've done the following:
I replaced the brake caliper on the rear right wheel on my own initiative (i installed a used one), which didn't solve the problem. The wheel continued to lock up and heat up occasionally.
I checked the brake line, it looks like new along the entire length of the vehicle, undamaged, except for a small section in the rear of the car where there is visible corrosion for a length of 5cm, but I would say that it's only external corrosion, so that the line can't be destroyed from the inside.
I used a compressor to blow out from the inside the entire lines for both the left and right rear wheels. If they were clogged with something, that would come out.
I took other ABR unit from a friend (to make sure it wasn't the problem), installed it and bleeded breaks.
While driving after all this was done, I noticed that both the rear left and rear right wheels are now locking up intermittently, at different times. I don't know if it has to do with hard braking or not. But I drove the car with one hard brake to a stop, continued driving for about 2-3km when I stopped and touched the wheels, the rear left was hot and the rear right was cold. I jacked up the wheels and while the car was on, transmission in N, and tried turning both by hands, they turned without resistance. I continued driving further for about 5km with one hard brake and when I stopped the rear left wheel was cold and the rear right was very hot. I jacked up again and both turned by hand without any problems.
I don't know what else to do, what could be the problem.
I don't know if it has anything to do with this, but I noticed during the last bleed break a shrilling sound (louder than it would normally be) after unscrewing the air to let out. That sound occurred in both the rear right and rear left wheels. Previously before all this (when I was changing ABR unit in November), such a sound was only heard in the rear right wheel.
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
"I don't know if it has anything to do with this, but I noticed during the last bleed break a shrilling sound (louder than it would normally be) after unscrewing the air to let out. That sound occurred in both"
Can you elaborate on this? What 'air' are you referring to?
Can you elaborate on this? What 'air' are you referring to?
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The air from the system when the brake is bled.
Since we blew out the brake lines with a compressor, there was no brake fluid left in them, so it had to go through the system to bleed the wheel.
Usually when the brake system is bled the sound of air being released was quiet but in these cases it was louder. And I don't know where it was coming from, whether it was from the ABR unit or somewhere else.
Since we blew out the brake lines with a compressor, there was no brake fluid left in them, so it had to go through the system to bleed the wheel.
Usually when the brake system is bled the sound of air being released was quiet but in these cases it was louder. And I don't know where it was coming from, whether it was from the ABR unit or somewhere else.
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The parking brake might seem to operate properly from the pedal and release, but there could be corrosion in the cable close to where it engages the brake. Have you verified that the cable moves freely at the brake?
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Does @BlackML550 have any suggestion or solution?
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2010 ML550 VIN WDC1641722A564750, 2010 B180
I thought about the parking brake - that is a separate system with brake shoes inside the hub? If so, I can't see how it's related. All I could suggest on that front is disconnect the parking brake, drive it and see if they problem reappears.
When you've bled the system - I'm assuming you're saying there's still air in the lines? It's sounds like it's been bled to death so there shouldn't be any air in the lines. If there is, you've got a leak. Can you confirm that there was air in the lines after they'd been bled?
When you've bled the system - I'm assuming you're saying there's still air in the lines? It's sounds like it's been bled to death so there shouldn't be any air in the lines. If there is, you've got a leak. Can you confirm that there was air in the lines after they'd been bled?
Last edited by BlackML550; Mar 8, 2025 at 07:14 AM.
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The OP said that he was experiencing hot wheels from brake engagement despite having fully serviced the hydraulic system. This seemed to make the parking brake the next suspect, inasmuch as if the parking brake was not releasing at the brake caliper, then the wheel would heat up as described, as would the brake fluid also, leading to the volumetric expansion of the fluid, and hence the overflowing reservoir. Since the parking brake cables have been checked to be moving freely, and releasing properly, it's back to square one. I am perplexed at this point with everything having been checked and/or replaced. What's left?
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This is a picture of the rear right wheel from the other night. You can see that the brake calipers suddenly lock up and won't let go of the disc.
All wheels are fully bleeded, while only brake fluid didn`t started to come out of the nipple on the calipers.
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In the opening post, "ABR" is mentioned -- do you mean the ABS? You might try pulling the fuse on the ABS unit. Have you checked the wheel speed sensors? If one or more are defective, the ABS or traction control might be engaging believing that braking the over-speed wheel is necessary.
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In the opening post, "ABR" is mentioned -- do you mean the ABS? You might try pulling the fuse on the ABS unit. Have you checked the wheel speed sensors? If one or more are defective, the ABS or traction control might be engaging believing that braking the over-speed wheel is necessary.
I did not change or check the tire pressure sensors. I calculate that if they are defective, I would have a diagnostic error. There is absolutely no error on the diagnostic..
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You've probably seen this forum post that discusses braking systems (https://mbworld.org/forums/e-class-w...ng-system.html). There are several systems and sensors that can induce braking and you seem to have eliminated them all as faulty. Hope you eventually resolve it.
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