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Discussion Starter · #1 ·
Is there a known, common spot to check for a brake leak near/on the master cylinder? I am noticing a small leak that will drip down on the frame near my divers side tire. It is visible from the fender well and is pretty much directly below the booster/master cylinder. I just checked my power steering fluid and it has not changed but my brake fluid is dropping some. The master cylinder is pretty saturated but I can't pin point a leak. The drip seems to appear about once a week, maybe more and does kinda dry up before I see a new spot.
 

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Discussion Starter · #2 ·
I am reading that leaks around this area are pretty common.
 

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Wipe on the underside, where the MC joins/bolts to the booster. There's a small open notch there for a drain....for when the seals in the booster fail.

If it's wet there, you're leaking PS fluid, not brake fluid.
While the PS reservoir may show full, it only takes a small amount of fluid to leak out, make a mess, and look like it's more fluid leaking than it is.
 

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Discussion Starter · #4 ·
Wipe on the underside, where the MC joins/bolts to the booster. There's a small open notch there for a drain....for when the seals in the booster fail.

If it's wet there, you're leaking PS fluid, not brake fluid.
While the PS reservoir may show full, it only takes a small amount of fluid to leak out, make a mess, and look like it's more fluid leaking than it is.
Thanks Hook! I will check this out. I just assumed its brake fluid because I can see that the level has changed in the reservoir above the master cylinder.
 

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You may have other issues with the low brake fluild. When was the brake fluid flushed last?
 

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Discussion Starter · #7 ·
And fluid isn't in the "low" yet. But it was close to the min mark and I filled it to just below the max line about two months ago. Now it is right in-between min and max.
 

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That may be why it's low.
You can have enough water accumulated in the fluid after 18mos, to lower the boiling point by half. Plus the water causes decay throughout the system components.

Yearly flush (it's on my spring list) is good.
If you pull the lid on the MC, and it's green.....ewwww.

Upgrade to DOT4, even better (draws less water).
The average DIY can easily handle it without help, and have a compressor.
https://www.harborfreight.com/brake-fluid-bleeder-92924.html
 

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Discussion Starter · #9 ·
That may be why it's low.
You can have enough water accumulated in the fluid after 18mos, to lower the boiling point by half. Plus the water causes decay throughout the system components.

Yearly flush (it's on my spring list) is good.
If you pull the lid on the MC, and it's green.....ewwww.

Upgrade to DOT4, even better (draws less water).
The average DIY can easily handle it without help, and have a compressor.
https://www.harborfreight.com/brake-fluid-bleeder-92924.html
Well Im about to roll 180,000mi and I am pretty sure the fluid has never been flushed :|

I didn't know it could be switched to DOT4 so thanks for that! I will have to google the process.
 

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Discussion Starter · #10 ·
But what's the compressor for?
Oh wait, I see it works with the bleeder in that link
 

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Discussion Starter · #11 ·
Well Hook, as usual, I think you're right. There is a lot of saturation and seepage around the brake booster. I ran my hand along the bottom of the brake booster and I did feel a little hole down there... that had yellowish, brown fluid dripping from it. Sounds like I need a new brake booster...

AND to flush my brake fluid of course!
 

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Well, I wish it was the MC and not the HB. One is much easier to swap than the other.

Consider removing the front driver's seat for better access up under the dash to swap it out.
You'll thank me later. :wink2:

Go new, not reman...they won't last. And new, has no core charge and requires no parts to swap from old to new.
https://www.rockauto.com/en/moreinfo.php?pk=10576556&cc=1446602&jsn=464

Also, when you pull the old one out, pull back the carpet at the firewall and make sure it wasn't also leaking fluid on the inside, and running down under the pad/carpet.
 

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Discussion Starter · #13 ·
Well, I wish it was the MC and not the HB. One is much easier to swap than the other.

Consider removing the front driver's seat for better access up under the dash to swap it out.
You'll thank me later. :wink2:

Go new, not reman...they won't last. And new, has no core charge and requires no parts to swap from old to new.
https://www.rockauto.com/en/moreinfo.php?pk=10576556&cc=1446602&jsn=464

Also, when you pull the old one out, pull back the carpet at the firewall and make sure it wasn't also leaking fluid on the inside, and running down under the pad/carpet.
Well this all sounds terrible... Think its something a low experienced, none mechanic like myself can tackle? I do all my own maintenance but thats about the extent of it...
 

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Simple bolt-on/off, it's just working up under the dash that can be a task (driver's seat out makes a world of diff).
4-nuts on the inside, unscrew two HP line fittings, hose clamp on the return line.

There"s a keeper on the pedal that can be a hassle, but easily conquered if you pick up one of these small screwdrivers.



Use a 12-pt socket on the reverse torx-plus nuts/bolts for the driver's seat, front two 1st, then slide the seat all the way forward for the rears, unplug and lift out.

I laid down a moving pad for comfort. :smile2:
I find that 1/4" drive sockets, extensions, and U-joints fit better for removing the nuts under the dash.


I cheat with on of these $30 palm air ratchets....little screamers they are (one of my fav tools);
https://www.harborfreight.com/3-8-eighth-inch-mini-palm-ratchet-wrench-99898.html
 

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Discussion Starter · #15 ·
Simple bolt-on/off, it's just working up under the dash that can be a task (driver's seat out makes a world of diff).
4-nuts on the inside, unscrew two HP line fittings, hose clamp on the return line.

There"s a keeper on the pedal that can be a hassle, but easily conquered if you pick up one of these small screwdrivers.



Use a 12-pt socket on the reverse torx-plus nuts/bolts for the driver's seat, front two 1st, then slide the seat all the way forward for the rears, unplug and lift out.

I laid down a moving pad for comfort. :smile2:
I find that 1/4" drive sockets, extensions, and U-joints fit better for removing the nuts under the dash.


I cheat with on of these $30 palm air ratchets....little screamers they are (one of my fav tools);
https://www.harborfreight.com/3-8-eighth-inch-mini-palm-ratchet-wrench-99898.html
Thanks for all the info! Is getting the MC off the Booster very difficult? Looks like its just two nuts? Is there enough room to get it out the way or will I need to unhook the brake lines on the MC and completely remove it from the truck too?
 

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No.
Remove the nuts from the studs and push the MC forward out of the way (there's enough flex in the tubing to move it and not crack the seals on the brake system).
 

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Discussion Starter · #17 ·
No.
Remove the nuts from the studs and push the MC forward out of the way (there's enough flex in the tubing to move it and not crack the seals on the brake system).
Awesome. Thanks a lot for all the info Hook! Looks like I know what my next "truck project" will be.

I can't help but sit here and wonder if I would have known the importance of servicing the power steering fluid, before mine started making noise, if this could have been avoided... 'dunno;
 

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if this could have been avoided..
Yes. Fresh fluid helps. And, you can make it much easier with that bleeder I posted.

Remove the rubber end for the wheel bleeder and drop the hose end in and suck out the PS fluid from the pump.
Add fresh fluid and you're gtg 'till the next engine oil change.

Installing a PS fluid cooler to remove the heat is the best....greatly prolongs the life of the components.

You're lucky with your LML, as earlier models were close to $400 years ago......for a Reman. 'uhNo
 

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another Inspirational pic :howdy

 
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Discussion Starter · #20 ·
Yes. Fresh fluid helps. And, you can make it much easier with that bleeder I posted.

Remove the rubber end for the wheel bleeder and drop the hose end in and suck out the PS fluid from the pump.
Add fresh fluid and you're gtg 'till the next engine oil change.

Installing a PS fluid cooler to remove the heat is the best....greatly prolongs the life of the components.

You're lucky with your LML, as earlier models were close to $400 years ago......for a Reman. 'uhNo
Yeah unfortunately I did not learn about flushing the PS fluid until my PS pump was squealing on cold starts. So I flushed it out and now I replace the fluid in the reservoir every oil change to keep it fresh. Doesn't make a sound now.

Doesn't the LML come with a cooler from factory? I thought I read that somewhere.
 
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