Brake fluid leak :(
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GLK250 ML350
Brake fluid leak :(
I did little bit search in the forum and can't find too much information regarding with brake fluid leak. During my last oil change, I noticed little light yellow oil around my front differential. I was suspecting it was my front differential seal leak, but now I am leaning more to believe it my brake fluid. The leak wasn't serious, it just a very slow leak. Yesterday, I flushed my brake with the pressure brake bleeder. After the flush completed, I noticed the a lot of brake fluid under my brake reservoir 
I believe the pressure brake bleeder must pushed significant amount of brake fluid though the crack, which caused the leak more noticeable. I did a test drive after the flush completed and the brake feels great, no issues. I made an appointment with my mechanic on Monday and now I am just debating whether to get the vehicle tow or drive down to the shop 
There are no sponge feeling on my brake and I checked the brake fluid this morning, it was perfect. The leak has turned back to very slowly leaking. What are the chance for me to lose the brake power during the drive down to the shop because of the slow leak ?
I believe the pressure brake bleeder must pushed significant amount of brake fluid though the crack, which caused the leak more noticeable. I did a test drive after the flush completed and the brake feels great, no issues. I made an appointment with my mechanic on Monday and now I am just debating whether to get the vehicle tow or drive down to the shop There are no sponge feeling on my brake and I checked the brake fluid this morning, it was perfect. The leak has turned back to very slowly leaking. What are the chance for me to lose the brake power during the drive down to the shop because of the slow leak ?
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GLK250 ML350
I don't think it the antifreeze. Maybe the brake fluid travel? Like if there is a leak in one the brake line, then the fluid just slowly travel to the diff area. I honestly don't know
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GLK250 ML350
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From: Northern NJ
GLK 350 / Porsche 993
Ok way too many things here let's take one at a time.
1) Sweating/oily front diff is fine. Mine has been this way for at least 5-6 years and probably more. Wipe off during the oil change and move on unless it really leaks leaving spots on the floor. That front diff has only 0.6L of fluid. If car has more than 80k miles I would flush it. Transfer case does the same.
2) Did you spill any brake fluid by chance? When doing brake job and pushing pistons back the level will go back up so if it was topped off it will overflow? Are you sure it's brake fluid? Brake res and master cylinder are unlikely to leak. The only thing that will cause a leak in braking system is either corroded brake line or old seal in the caliper both of which are likely to be in the wheel area.
3) how did you use power bleeder? Do you use dry (just build pressure with powerbleeder) or wet (fill up power bleeder with break fluid) method? How much pressure do you build it to?
1) Sweating/oily front diff is fine. Mine has been this way for at least 5-6 years and probably more. Wipe off during the oil change and move on unless it really leaks leaving spots on the floor. That front diff has only 0.6L of fluid. If car has more than 80k miles I would flush it. Transfer case does the same.
2) Did you spill any brake fluid by chance? When doing brake job and pushing pistons back the level will go back up so if it was topped off it will overflow? Are you sure it's brake fluid? Brake res and master cylinder are unlikely to leak. The only thing that will cause a leak in braking system is either corroded brake line or old seal in the caliper both of which are likely to be in the wheel area.
3) how did you use power bleeder? Do you use dry (just build pressure with powerbleeder) or wet (fill up power bleeder with break fluid) method? How much pressure do you build it to?
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Thread Starter
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Joined: Feb 2018
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GLK250 ML350
Ok way too many things here let's take one at a time.
1) Sweating/oily front diff is fine. Mine has been this way for at least 5-6 years and probably more. Wipe off during the oil change and move on unless it really leaks leaving spots on the floor. That front diff has only 0.6L of fluid. If car has more than 80k miles I would flush it. Transfer case does the same.
2) Did you spill any brake fluid by chance? When doing brake job and pushing pistons back the level will go back up so if it was topped off it will overflow? Are you sure it's brake fluid? Brake res and master cylinder are unlikely to leak. The only thing that will cause a leak in braking system is either corroded brake line or old seal in the caliper both of which are likely to be in the wheel area.
3) how did you use power bleeder? Do you use dry (just build pressure with powerbleeder) or wet (fill up power bleeder with break fluid) method? How much pressure do you build it to?
1) Sweating/oily front diff is fine. Mine has been this way for at least 5-6 years and probably more. Wipe off during the oil change and move on unless it really leaks leaving spots on the floor. That front diff has only 0.6L of fluid. If car has more than 80k miles I would flush it. Transfer case does the same.
2) Did you spill any brake fluid by chance? When doing brake job and pushing pistons back the level will go back up so if it was topped off it will overflow? Are you sure it's brake fluid? Brake res and master cylinder are unlikely to leak. The only thing that will cause a leak in braking system is either corroded brake line or old seal in the caliper both of which are likely to be in the wheel area.
3) how did you use power bleeder? Do you use dry (just build pressure with powerbleeder) or wet (fill up power bleeder with break fluid) method? How much pressure do you build it to?
The oil looks like is the brake fluid to me2) Yes I did accidentally spilled the brake fluid during the flush
I forgot to release the pressure before I unscrew the connector from the master cylinder. i cleaned up the best3) I filled up the power bleeder with brake fluid and I built it up around 15psi to 25 psi. Most of time just 20 psi.
I already arranged an tow truck and bring the vehicle to my mechanic to check it out
I don't think feel like putting people on road at risk. Hopefully it nothing major and the repair bill is reasonable. 2020 is such a rough year. Thank god we are more than half way done
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From: Miami, FL
2009 E63
1) I am not sure if my front diff is leaking The oil looks like is the brake fluid to me
2) Yes I did accidentally spilled the brake fluid during the flush I forgot to release the pressure before I unscrew the connector from the master cylinder. i cleaned up the best
3) I filled up the power bleeder with brake fluid and I built it up around 15psi to 25 psi. Most of time just 20 psi.
I already arranged an tow truck and bring the vehicle to my mechanic to check it out I don't think feel like putting people on road at risk. Hopefully it nothing major and the repair bill is reasonable. 2020 is such a rough year. Thank god we are more than half way done
The oil looks like is the brake fluid to me2) Yes I did accidentally spilled the brake fluid during the flush
I forgot to release the pressure before I unscrew the connector from the master cylinder. i cleaned up the best3) I filled up the power bleeder with brake fluid and I built it up around 15psi to 25 psi. Most of time just 20 psi.
I already arranged an tow truck and bring the vehicle to my mechanic to check it out
I don't think feel like putting people on road at risk. Hopefully it nothing major and the repair bill is reasonable. 2020 is such a rough year. Thank god we are more than half way done
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From: Miami, FL
2009 E63
right... post master cylinder. This pressure was applied before the master cylinder and could be cause a leak between the reservoir and the master cylinder.
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From: Northern NJ
GLK 350 / Porsche 993
Could have been also coming out through the cap I guess. I never fill up power bleeder, I just use it to build up pressure. 15psi is sufficient and make sure not to go below min level and do this on even ground.
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Finally got my car back. It turn out no leak in the brake system. It was actually my front differential seal leak. The leak wasn't not serious and my mechanic recommend not to change the seal, just keep doing the the flush. It turned out really good after the repair was completed. The sad part was, the glk need a new set of fuel injectors, which is like $1700
oh well. Thx everyone for help.
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GLK250 ML350
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With new injectors in place, I would keep a close eye on the valvecover area for any coal or bitumen appearing over the next several oil change intervals. Search "black death" and you'll know what I'm referring to. In short, it's caused by improper injector seal placement thereby enabling fuel and oil vapors past the injector seal during combustion. Quite common on Bluetecs for whatever reason, but especially if injectors have been worked on.
I would also recommend a cleaning interval for the fuel system, right before every fuel filter change (should be around 40K miles). LiquiMoly makes a product called Diesel Purge, it has helped many to restore their fuel injection issues including smoke, knocking, low power, low fuel mileage, etc.
I would also recommend a cleaning interval for the fuel system, right before every fuel filter change (should be around 40K miles). LiquiMoly makes a product called Diesel Purge, it has helped many to restore their fuel injection issues including smoke, knocking, low power, low fuel mileage, etc.
Thread Starter
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GLK250 ML350
With new injectors in place, I would keep a close eye on the valvecover area for any coal or bitumen appearing over the next several oil change intervals. Search "black death" and you'll know what I'm referring to. In short, it's caused by improper injector seal placement thereby enabling fuel and oil vapors past the injector seal during combustion. Quite common on Bluetecs for whatever reason, but especially if injectors have been worked on.
I would also recommend a cleaning interval for the fuel system, right before every fuel filter change (should be around 40K miles). LiquiMoly makes a product called Diesel Purge, it has helped many to restore their fuel injection issues including smoke, knocking, low power, low fuel mileage, etc.
I would also recommend a cleaning interval for the fuel system, right before every fuel filter change (should be around 40K miles). LiquiMoly makes a product called Diesel Purge, it has helped many to restore their fuel injection issues including smoke, knocking, low power, low fuel mileage, etc.
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