Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 08-14-2022, 01:51 PM
Registered User
 
Join Date: Feb 2007
Posts: 244
Service life of rubber brake hoses?

Didn't fnd what I was looking for in the archives here so...

For my 1985 300CD, my brake system maintenance routine is:
I flush the brake system every spring and use DOT 3 fluid. Always clear, never discolored or holding visible-to-the-naked-eye particulate matter.

This is a car that I don't drive much...600 miles or so a year and it is garaged in a low humidity climate.

So, my question:
Anyone have some wisdom to share on the service life of rubber brake hoses? Or perhaps it is a matter of checking them for bulges or obvious signs of wear?

Thanks for any insight on this.

Reply With Quote
  #2  
Old 08-14-2022, 03:07 PM
Registered User
 
Join Date: Sep 2001
Posts: 2,765
Not scientific but replace them every 10 years conservatively??? What say others?
__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer
Reply With Quote
  #3  
Old 08-15-2022, 10:37 AM
Graham's Avatar
Registered User
 
Join Date: Nov 2004
Location: Ontario, Canada
Posts: 4,393
You probably don't need to flush that often, but it does help prevent internal corrosion. I doubt many owners do it that often. I don't and at present am paying for it with one frozen front caliper.

I don't see much chance of the rubber hoses deteriorating when car is hardly used. If they are good quality hoses, I would just inspect the exterior when you do your flushes. I am about to change my front hoses. They "look" OK, but the end crimps are rusted and the hoses are abut 8 years old. Car gets driven about 6000 km/yr.

By the way, I once had one hose collapse internally - Brakes/hoses had not long before been replaced by independent MB shop. Brakes were noisy and then locked up while I was on my way back to the shop. They had to come and release pressure at side of road before carefully driving car to their shop.
__________________
Graham
85 300D,72 350SL, 98 E320, Outback 2.5
Reply With Quote
  #4  
Old 08-15-2022, 03:34 PM
Registered User
 
Join Date: Oct 2012
Posts: 5,924
About every seven years for a car in normal service. Is the recommendation I remember with changing brake hoses.

For the cost involved replacing the brake fluid yourself every year probably further eliminates internal corrosion. Cheap enough to do. Probably has no bearing on the life of the hoses though.

I can think of a few factors. Those hoses are in fairly constant motion. The hard inner tube surrounded by rubber might only flex so many times. So milage driven per year may be a real factor.

When they block off I have to wonder if they have flexed just a little too much and the internal hard tube kinks as strength to resist it has decreased with use and age,

Brake fluid of course is hydroscopic and you can buy a tester. Thar should indicate when moisture in the fluid is building. Or you might test cheap.

Take a drop of the fluid when new and drop it on a small hot sheet of metal. I figure then take a sample of the fluid from the master cylinder and repeat. If is spits on contact you have moisture.

It would be interesting if any moisture was detectable by testing after only one year. Many manufactures want the fluid addressed every two years.

Not very scientific really but perhaps an indicator?
Reply With Quote
  #5  
Old 08-15-2022, 05:46 PM
Registered User
 
Join Date: Feb 2007
Posts: 244
Thank you for the posts and good information. All helpful.

As for why I have been flushing the brake system yearly, I got to wondering how I got on that schedule. It was a FSM.

Turns out that in the FSM "Maintenace Manual Model Year 1981 - 1993", there is the following:
"Note: During its service life, the boiling point of brake fluid will decrese as a result of the moisture absorbed from the atmosphere. When the braking system is under extreme stress, this moisture can vaporize. For this reason, the brake fluid must be changed once a year [yes, they bolded this in the manual], prefereably in spring on models 124 and 201 through 03/91 production as well as models 107, 123, 126. On models 124 and 201 starting 04/91 production, and models 129 and 140 the brake fluid must be changed once every two years [again, their bolding]."

Of course:
1. This was written decades ago.
2. As I indicated, my car isn't driven much and when it is, things are rather leaisurely but do include some freeway driving from time to time (where the posted speed limit is 70 MPH...ugh in my relic 5 cylidner diesel, LOL).

Thanks again-
Reply With Quote
  #6  
Old 08-15-2022, 06:30 PM
jay_bob's Avatar
Control Freak
 
Join Date: Oct 2011
Location: Columbia, SC
Posts: 3,941
From the esteemed whunter:

Brake:
__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech
Reply With Quote
  #7  
Old 08-15-2022, 06:33 PM
Registered User
 
Join Date: Feb 2007
Posts: 244
Quote:
Originally Posted by jay_bob View Post
From the esteemed whunter:

Brake:

Ah, there it is! Brilliant!
Thank you for posting this!
Reply With Quote
  #8  
Old 08-19-2022, 06:59 PM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 3,115
Racers flush thru new fluid before each race. In the real world it depends on where you live and how sealed. The rubber test bulbs on top of the reservoir seem "bad idea", especially since the rubber cracks. I would say flush every 4 years in FL and 10 years in CA. Most owners never flush. I don't since I use DOT 5 silicone fluid.
Reply With Quote
  #9  
Old 08-19-2022, 08:00 PM
Graham's Avatar
Registered User
 
Join Date: Nov 2004
Location: Ontario, Canada
Posts: 4,393
I just changed my front hoses on the 300D. Last time was 2014. The old ones appeared OK, but looking inside the lower end of one, there was something pink in there! Not sure what, but it would likely have partially blocked the line. Maybe the liner had started to disintegrate.

Another advantage of changing regularly that I have found, is that the connection to the hard lines has to be disconnected. Not always easily! But it helps make it easier for the next time.
__________________
Graham
85 300D,72 350SL, 98 E320, Outback 2.5
Reply With Quote
  #10  
Old 08-20-2022, 05:57 AM
Registered User
 
Join Date: Feb 2003
Posts: 278
Around every 2 years is about how I remember most car makers specify changes, this is what I follow.

On brake lines, I inspect everytime the car is in the air, force of habit. I replace when I see any deterioration of the rubber, usually fine cracks.
Reply With Quote
  #11  
Old 08-20-2022, 10:15 PM
Registered User
 
Join Date: Sep 2006
Location: Middle TN
Posts: 4,154
Too bad Roy isn't working for Pelican. Service was much better when he was. Now, I give them 1st & last look but am more aware of other vendors and not as loyal.
__________________
85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.
Reply With Quote
  #12  
Old 08-22-2022, 01:31 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
Quote:
Originally Posted by Junkman View Post
Too bad Roy isn't working for Pelican. Service was much better when he was. Now, I give them 1st & last look but am more aware of other vendors and not as loyal.
I miss calling in orders to him as well.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #13  
Old 08-22-2022, 01:36 PM
Registered User
 
Join Date: Oct 2012
Posts: 5,924
Quote:
Originally Posted by Graham View Post
I just changed my front hoses on the 300D. Last time was 2014. The old ones appeared OK, but looking inside the lower end of one, there was something pink in there! Not sure what, but it would likely have partially blocked the line. Maybe the liner had started to disintegrate.

Another advantage of changing regularly that I have found, is that the connection to the hard lines has to be disconnected. Not always easily! But it helps make it easier for the next time.
Could make sense for uneven pad wear. If what you see in that old hose. You may not have been getting full release of the brake fluid pressure on that side.

Proof almost would be if the pads on that side where reducing faster than the other side. Some hoses do fail well before the vehicles are 7 years old. First time I saw it was on our Chrysler product with the car at about 3 years of age. Hose closed up totally solid internally.

Strange the way memory works. For whatever reason even though it was decades ago. It was on the front passenger side.
Reply With Quote
  #14  
Old 08-22-2022, 03:23 PM
Graham's Avatar
Registered User
 
Join Date: Nov 2004
Location: Ontario, Canada
Posts: 4,393
After reading some of the comments here about regular flushing and replacement of hoses whether needed or not, I noted one thing not mentioned.

This may mainly apply in areas where salt is used, or warm coastal areas where rust happens. I find that the main cause of brake problems on our W123, is that corrosion (or dirt) prevents the pads from properly sliding. Worse if car is not used regularly.

I just finished cleaning up my rear brakes. Had trouble removing the pads that went in fine when I last changed them (in 2014, I think!). Almost no wear on pads or disks, but rust had developed on the pad backing plates causing them to jam. Pins were also rusty, but they cleaned up OK. Spring was rusted, but had to go back in (no spares).

I sanded the edges of the pad backing plates smooth on table belt sander. Re-installed. Applied Syl-Glide to top/bottom edges as well as to pins and guide holes. Rubbed a bit on the hose crimps which also had rust (after wire brushing)

BTW, I didn't change the hoses. They looked fine and are less critical than fronts.

Another issue, was the bleeders. I suspect they are not standard. They first of all needed heat to release. Then when flushing/bleeding they tended to leak around the threads unless only barely open. I bumped up pressure flusher pressure and got them done. Bleeder threads are I think too short. Looking for a set of OE/ATE bleeders. Mercedes part 0004201755
__________________
Graham
85 300D,72 350SL, 98 E320, Outback 2.5
Reply With Quote
  #15  
Old 08-27-2022, 11:12 AM
Registered User
 
Join Date: Oct 2012
Posts: 5,924
Ken to me had a very good segment or tutorial on doing brakes in general. He used a 300d as the working example. Lots of good suggestions I thought. Catching the details of a brake job are productive in general.

One he may not have mentioned comes to mind though. Behind the stainless sliders for the brake pads. After cleaning off any rust behind the stainless steel sliders.

Put a small amount of brake grease in the area before putting the stainless steel sliders in. Or replacing them. Rust by nature or iron oxide do expand when the metal is changing state with rusting. For the same reason it is important to get that area of the caliper derusted.

I do live in the rustbelt though. It really does reduce the chances of sticking pads with time.

I also have mentioned before. Cut a small length of fuel hose to fit snugly over the bleeder screws. Put some grease on the bleeder. Slide the small segment of hose over the bleeder. Put a dap of grease on the top.

Next time you need to open the bleeders it should go easy. Detail item again that really costs nothing to do. In rustbelt areas you are going to need heat or land up breaking some bleeders otherwise usually. Many bleeder screws are also so small with a hole drilled down through then as well. Any rust can and does reduce their strength further. Thee was not much material in them when new to start with.

I did not pick this approach up anywhere, It was just common sense to develop after some time. Good approach for especially any vehicle you intend to have around a long time. you have to live in a rustbelt to really know What dealing with old bleeder screws can be like.

Fuel hose comes in many sizes. Use one that is a snug fit.


Last edited by barry12345; 08-27-2022 at 11:41 AM.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 10:28 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page