300SDL BRAKE PROBLEM - PeachParts Mercedes-Benz Forum

brandlj · #1 03-09-2010, 08:53 AM

I am going to describe some symptoms that have just started on my 86 300sdl. When I step on the brakes, my left front wheel pulls hard to the left. It is kind of scary. I looked at my brake fluid, it was not that dirty, but I flushed the system on Sunday anyway. I used my Motive power brake flush device and started at Right rear. I used 10psi in the flush unit. The right rear flushed quickly, as did the left rear. Then when I went to the right front, it barely dribbled out of the bleeder valve. I let it dribble for a while, then I did the left front and it flushed normally. I am guessing that my right front rubber brake hose must be constricted internally? I ordered two new hoses for the front. Am I on the right track?
My hypothesis is that the right front caliper is not working as well as the left because of the constriction in the brake hose. By the way, the left front wheel was black with brake dust, the right not so much.
Or could it be that my left caliper is sticking?
Any input would be appreciated.
Thanks

benhogan · #2 03-09-2010, 09:04 AM

the brake hose has swollen to the point that fluid no longer flows.

you are on the right track. that is indeed the issue.

i suggest you change all 4 hoses. if one is bad, the other three are not far behind.

brandlj · #3 03-09-2010, 09:09 AM

Quote:

Originally Posted by benhogan

the brake hose has swollen to the point that fluid no longer flows.

you are on the right track. that is indeed the issue.

i suggest you change all 4 hoses. if one is bad, the other three are not far behind.

That's what I am thinking also. Hopefully they will come in this week and I will change the front on Saturday and see what happens. You are probably right though that I should change all 4 hoses. They are the same age.

benhogan · #4 03-09-2010, 09:32 AM

Quote:

Originally Posted by brandlj

That's what I am thinking also. Hopefully they will come in this week and I will change the front on Saturday and see what happens. You are probably right though that I should change all 4 hoses. They are the same age.

be sure to cut open the old hose so you can see how small the hole has become.

if possible, you should use a flare nut wrench when you replace the hoses. the last thing you want is to round off the fastening nuts.

if you do not own a set of flare nut wrenches, you can use two wrenches in tandem i.e. two wrenches on the same nut.

the nuts are probably pretty old and tight. just a tip

Junkman · #5 03-09-2010, 10:16 AM

Generally, car moves opposite mal-functioning front brake. RF not working = pull to left.

brandlj · #6 03-09-2010, 10:31 AM

Quote:

Originally Posted by benhogan

be sure to cut open the old hose so you can see how small the hole has become.

if possible, you should use a flare nut wrench when you replace the hoses. the last thing you want is to round off the fastening nuts.

if you do not own a set of flare nut wrenches, you can use two wrenches in tandem i.e. two wrenches on the same nut.

the nuts are probably pretty old and tight. just a tip

Thanks for the info. I have a set of flare nut wrenches. Believe it or not, I just spent last weekend replacing wheel cylinders, brake hoses, brake shoes, brake drums, and wheel bearings on my 67 VW Beetle. My cars are keeping me busy this spring!

brandlj · #7 03-09-2010, 10:33 AM

Quote:

Originally Posted by Junkman

Generally, car moves opposite mal-functioning front brake. RF not working = pull to left.

That seems to make sense to me also, I hope I caught this in time and I don't have a set of half worn out brake pads on the left front. I actually noticed the discrepancy in the amount of brake dust about 500 miles ago. The brake pulling just started though. Thanks for the input!

brandlj · #8 03-13-2010, 12:21 PM

SUCCESS!!!!!!

I replaced the rubber brake hoses today on the 300sdl. The Right front was completely blocked internally. I cut the hose open and it was so swollen, nothing could pass thru. 4 new hoses. brake bleed and all is well with the world!

brandlj · #9 03-17-2010, 09:35 AM

UPDATE:

I spoke too soon. Started pulling to the left again. To make a long story short... rebuilt front calipers, new pads, new pad sensors, and a brake fluid flush and NOW ALL IS WELL!!!!
Oh, Rotors were turned a little to smooth them out. Still within factory specs.

vstech · #10 03-17-2010, 09:39 AM

how much was it to turn them?
"within factory specs" means the rotors weren't worn beyond the "too thin" limit. but I'd not drive that way.
ya ought to get new rotors in there...