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Discussion Starter · #1 ·
2020 126" cargo van in for its B service Tuesday. Mileage: 18945. A bit short of the "20,000" miles this service is supposed to happen but I'm planning on a drive to CA very soon and wanted the van serviced before I left.

Cost came to $692.03. Just happened to receive a mailer from M-B offering me a $60 discount on a B service. This was accepted by the dealer service.

Got an oil/filter service, new wiper blades, cabin air filter (was told engine air filter not due to be changed yet). Brake fluid flush/bleed. Tires rotated. Front to back, back to front. Tire pressures all checked/set (including the spare).

Keyfob batteries replaced.

Vehicle given a pretty thorough going over. (At its 'A' service received a video of the vehicle being gone over.)

All items on the multi-point inspection came back in the green. I take good care of the van, it leads a pretty easy life, so this is not surprising. Still nice that all is well.

Dropped van off Tuesday at 2pm. Got a shuttle ride home. Van ready before noon Wednesday.
 

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I guess that's what I am in for, in a few weeks. The computer in mine is starting to complain.

The brake fluid flush and replace ... :cautious: I have 14k miles!

Why did this in recent years go from something that was due with a major brake service, or maybe 4 to 5 years; into do it on an essentially new vehicle and every 2 years?

I know with one of my earlier vehicles, the Dodge/Chrysler/Jeep dealership was essentially scamming everybody who came through the door for batteries and brake fluid changes. Long story short. I had a brand new Town and Country, with a noticeable vibration issue around 48 49 mph. Lots of trips to the dealer to try to get it sorted. Every time, without fail, the service advisor came back to little old ladies and guys, the mechanic tested your battery it tests weak and there is water in your brake fluid. During my 1 year oil change appointment same thing. Weak battery. Moisture in the fuel lines. Declined. The battery did fine for FIVE years, including cross country trips with very cold falls and winter times up North. No brake issue.
 

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I guess that's what I am in for, in a few weeks. The computer in mine is starting to complain.

The brake fluid flush and replace ... :cautious: I have 14k miles!

Why did this in recent years go from something that was due with a major brake service, or maybe 4 to 5 years; into do it on an essentially new vehicle and every 2 years?
It’s the DOT4 brake fluid. It has to do with boiling temperature and how much moisture it can absorb before you can start having separate water in the brake lines, which can boil when hot, become a compressible gas and be an issue for braking. As far as I am aware, this has been the normal maintenance requirement on some European vehicles for decades now. I have a 2002 VW that uses the same brake fluid and 2-year flushes.
 

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Interesting.

Could that have come about after 2000 ... maybe? Because up to that point, driving both VAG & PSA within the family and a variety of vehicles at work; brake fluid flush and change never came up as routine maintenance. Oil changes, tires, brake pads, battery ... sure; and we had comprehensive annual automobile inspections. Most people took their vehicle in for a small service appointment before going to inspection, or just let the mechanic or his wife ( small indie shop ) or a staff member ( larger shops ) take it in for testing at the regional office; instead of taking time off work and dealing with the hassle.

I understand the importance of good fluids and routine maintenance; I DIY the maintenance on our outdoor power equipment. Just seems a bit strange to change the brake fluid every 2 years. In a closed system, where does the water come from, how much water does it absorb ... out of ?

I think with my previous van, up to 48k, I don't think there was every anything about brake pads, brake fluid, just the tires starting to get low on the bars ... So, I'm just a bit curious regarding MB pushing on this.

Anybody used an at home / DIY moisture tester?
 

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Little point in testing when fluid is cheap and bleeding is quick. The stuff is hygroscopic. This is to help prevent pockets of water in the system that could boil or cause corrosion.

Not sure about you, but I like good brakes. I hate mushy brakes or touchy brakes. I also don't want the automatic braking system impaired by inferior fluid.
 

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I'm with you on good stopping power and no mushy brakes. I guess I forgot brakes are a standard part of B, and yes, the fluid is probably cheap enough; but I'm a bit surprised that the bill for a Metris B service ends up being $700.
 

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Discussion Starter · #8 ·
Interesting.

Could that have come about after 2000 ... maybe? Because up to that point, driving both VAG & PSA within the family and a variety of vehicles at work; brake fluid flush and change never came up as routine maintenance. Oil changes, tires, brake pads, battery ... sure; and we had comprehensive annual automobile inspections. Most people took their vehicle in for a small service appointment before going to inspection, or just let the mechanic or his wife ( small indie shop ) or a staff member ( larger shops ) take it in for testing at the regional office; instead of taking time off work and dealing with the hassle.

I understand the importance of good fluids and routine maintenance; I DIY the maintenance on our outdoor power equipment. Just seems a bit strange to change the brake fluid every 2 years. In a closed system, where does the water come from, how much water does it absorb ... out of ?

I think with my previous van, up to 48k, I don't think there was every anything about brake pads, brake fluid, just the tires starting to get low on the bars ... So, I'm just a bit curious regarding MB pushing on this.

Anybody used an at home / DIY moisture tester?
The brake hydraulic system is not a closed system. The reservoir is open to atmosphere. Due to the heating/cooling cycles outside air -- with some moisture in it -- is brought in and the brake fluid grabs on to this moisture.

While the reservoir fluid still looks good the fluid that comes out of the brake calipers is nasty looking.

My first memory of 2 year brake fluid flushes came with my purchase of a 2002 Boxster in January of 2002 and then a 2002 VW Golf TDi in March 2002.

I had the brake fluid flushed and bled every 2 years. Thought it a bit of overkill but I generally go with what the factory calls for.

Then one time I let the Boxster brake fluid go. I didn't realize it at the time. I was very busy with elderly parents and lost track of time. Clutch action deteriorated. Shifting was no longer smooth. Long story short I had the car in -- fearing it was time for a new clutch possibly a new 5-speed transmission.

But the SA looked at my vehicle's service records and noted it was past due for a brake fluid (and clutch fluid the two hydraulic systems share fluid) service and recommended this service before going deeper.

Approx. $200 for a brake (and clutch) fluid service vs. around $4K for a new clutch and God only knows what a new transmission would have cost. I decided to gamble $200.

Turned out the fluid service made all the difference in the world. Excellent clutch action was restored and shifting was once again buttery smooth. I could not detect any change in the brakes.

But the clutch and shifting (arising from the now correctly operating clutch) improvement made me a believer of 2 year brake fluid flush/bleeds.

As if I needed further convincing my 2018 at around 15K miles had a brake wear light come on. Turns out the driver side rear pads worn out. Quite a mystery as to why as I didn't drive the car that hard. Had the rear brakes done: New pads. New rotors. But for some reason I forgot to have the brake fluid service done.

After new brakes I noticed during turns the stability control was activating the rear brakes and most often the driver side. I had noticed this before having new brakes installed but I never paid much attention to it.

But now with the bill for new brakes still smarting my wallet I paid more attention to the brakes. I tried slowing down taking sweeping right hand turns but this didn't help. On a hunch I had the brake fluid flushed/bled. After the too quick to engage stability control issue was no more. Not sure how a brake fluid service "fixed" this but it apparently did.

At any rate the van got its 2 year brake fluid flush/bleed. And will continue to get these as long as I own it.
 

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Discussion Starter · #9 ·
Little point in testing when fluid is cheap and bleeding is quick. The stuff is hygroscopic. This is to help prevent pockets of water in the system that could boil or cause corrosion.

Not sure about you, but I like good brakes. I hate mushy brakes or touchy brakes. I also don't want the automatic braking system impaired by inferior fluid.
The van brakes feel a bit better. I have had brake fluid flushes/bleeds done to other vehicles and with just one exception never noticed any change for better (or worse) from the brakes but the van brakes feel less sensitive, less prone to I guess as best I can describe it variable braking action. Some times I would have sworn the brake discs were "warped" as I rolled to a stop with the brakes applied. But underway and with varying degrees of braking no signs of any issues.

Might mention I bought the van new in August 2020. But before I bought it the van sat around some time (months) outside experiencing the temperature swings and as a result experiencing some exchange of air inside the reservoir with outside air. All the time the brake fluid accumulating more and more moisture.
 
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