Replacing Brake Lines
 

What's the proper procedure for replacing the brake lines? Do you have to bleed the entire system or is there a way to close off the line to the master cylinder, replace the line going to the caliper and then bleed the system. Thanks.

I just did that on my 92 300 TE. You might want to use the appropriate size flare nut wrenches also call line wrench if the fittings are real tight. Here's how I did it.

-loosen slightly but do not remove top and bottom fittings of old hose
-completely disconnect top connector first, put a rag around the top of where you disconnect it to absorb the small amount of fluid that will leak out
-unscrew the entire hose, i.e., at this point only the bottom is connected
-have your new hose ready and tight bottom first, completely tight
-tighten top fitting
-go on to the next one
-when all four are done bleed brakes by whatever method you prefer

I did not have to add any fluid to the brake resorvior during the hose replacement since the level never got below 1/2 of being full.

Are you talking about the rubber hoses or the metal brake lines? Ron assumed the rubber hoses and I'll do the same. I cut the hose with snips first. Then I can get a closed end wrench on the fittings on both ends to get the best grip I can. I feel that gives me the best chance of getting it off without potential damage due to a tight fitting twisting the metal line off. Some folks use heat. Some bathe it in penetrating oil.

Len

If you are replacing a line BEFORE a junction,split or T make sure you bleed it at the T before bleeding at the caliper.

Yes, the rubber hoses. I'm not sure it's necessary to cut them. I leave everything intact as long as possible, that way hardly any brake fluid leaks out. I guess if the connectors can not be loosened with a line wrench then that would be an option, I've found that if I can get a line wrench on a fitting like that it will not be damaged.

If you don't own a set of flarenut wrenches, buy a set. For the DIYer, you can buy a very good set of Metric flarenut polished wrenches at Sears for about $40. You are talking about doing brake work. You are dealing with a subsystem of your car that holds your life and that of your family in its hands. Do it right.

Along the same lines, anytime you open the system, COMPLETELY and THOROUGHLY flush and bleed the system. A quart of brake fluid costs less than $5. How much is the safety of you and your family worth? $5?

If you will COMPLETELY flush your brakes annually, you will probably NEVER have any hydraulic brake issues. Is the safety of you and your family worth $5 worth of brake fluid per year? I know my family is worth it.

Good luck,

You've obviously never met my family. :P

Jeff Pierce

I agree with Larry, get yourself a good set of flare end wrenchs and make sure they include the 11mm (!) as this is the size at the ASR/ABS unit (and probably the same for the standard ABS hydraulic pump). I purchased a set at harbor freight tools and didn't look too closely at it only to realize that it skipped the 11mm...back to another store.

Good luck!

I prefer to empty the reservior before starting and then fully bleed the system when done. I've damaged enough paint on cars over the years to have become extremely paranoid about brake fluid.

Thank you for your replies. One last question. Do you have to use loctite?

on that
 

i would not.

but get it good and tight.

tom w

No, not on those type of fittings.

Also I would not empty the reservior, that could cause more problems like making it harder to bleed the system.

What brand of brake hoses would be considered original for a 1990 300te?

Phil at Fastlane lists the Mfg for the fronts:

Corteco/Freudenberg

and rears:

PBR

Dealer wants $50 apiece, so I want to buy online. Also, are steel braided lines worth considering?

When I did mine it was easier than I thought it would be. A little brake fluid drips out but not enough to cause a problem. Get a Motiv power bleeder. The lines I got were like $12 a piece. I think I read that stainless steel are actually less reliable than the plain rubber for general use.

I just did this on my 1991 300CE. You might have another person handy to bleed the system. Before loosening anything, clean carefully around the flange where your new hose attaches to the thin metal line. Lots of grit there plus you'll then see the 12pt cutout for the upper fitting of your new hose. Wipe up any brake fluid immediately.

glenmore
1991 300CE
2000 C280
1990 LS400