Brake Bleeding Problem 107.044

[Earl Kiker]

Gentlemen & Others,

In the process of getting my recently acquired 450SL back on the road, I replaced all four brake flex hoses. They were dated 10/78 and beginning to crack and leak. The replacements went without a challenge. However I can't get the system to bleed out at all. The car is on the two left wheels a jack stand at the right front and a floor jack at the right rear. The right rear being the highest of the four corners.

I am attempting to bleed the system at the right rear as it is the furtherest from the master cylinder. Initially I got maybe 5-6 ounces of rancid fluid, then nothing. We pumped and vented for about an hour but with absolutely no result. I made certain to keep check on the fluid level in the reservoir to make sure we didn't pump air into the system.

Any comments and suggestions both welcomed and appreciated.

Thanks in advance,

Earl Kiker
Houston

PS: While I'm here begging for help, I guess I might just get it all done at once. If anyone has a vacumn diagram for this unit I'd be very grateful for a copy.

Thanks again.

 

[eric242340]

Try gravitity bleed first. This means you open all four bleed screws and wait and wait and wait. Does the fluid leak out on its own? Second with all bleed screws open pump the pedal and keep pumping until it starts to flow. With the gravity feed system, you open all the bleed screws and the brake fluid pushes the air out of the system, albeit slowly, so you have to be patient. You will probably find that three of four brake bleed screws work under the gravity system, therefore you know where the air is. Once three are running, you can bleed the fourth in the normal manner.

 

[bigasotonuk]

Hi,
I,ve had similar problems with motor bike brakes and gravity bleeding does work like Eric says.
You say that you are bleeding the system from one of the rear wheels, someone correct me if i,m wrong but i,ve always been led to believe that you bled the the brakes from the bleed nipple closest to the master cylinder and worked away.
That may be your problem m8.

 

[television]

One point to bear in mind is that only one master cylinder of fluid can pass on any one stroke, when the pedal is up,the tank will fill the cylinder,once you press the pedal the filling hole is blanked and no further filling takes place till the pedal is released. it cant work any other way, otherwise when you pressed the pelal the fluid would be forced back to the tank.

Malcolm

 

[eric242340]

One point to bear in mind is that only one master cylinder of fluid can pass on any one stroke, when the pedal is up,the tank will fill the cylinder,once you press the pedal the filling hole is blanked and no further filling takes place till the pedal is released. it cant work any other way, otherwise when you pressed the pelal the fluid would be forced back to the tank.

Malcolm

Not so with all four bleed valves open

 

[Earl Kiker]

Gentlemen,

Thanks to you all! I'll try the Gravity Method first. It makes perfect sense to me. I was always taught to go to furtherst, highest point from master cylinder to bleed. But of course, I never encountered this problem before.

Thanks again,

 

[television]

Once it starts it speeds up so get ready for the fronts.

Malcolm

 

[IAN MAC]

And if pumping the pedal gets too much, then get hold of a one man pressure bleeding system that works from a spare tyre. Keeps the tank topped up as it goes.

 

[Earl Kiker]

Eric,

Your "Gravity System" performed flawlessly! Thanks so much for the heads up! Left all four open for about 10 minutes and they started to run. Shut them off and started bleeding at the slowest running and worked my way around. All is sweetness and light...and the darned thing actually stops!!

As you might have surmised by now, this is my first M/Benz. I got SERIOUSLY hooked on Jaguars many years ago and can virtually build any one of those. But still have tons to learn about the Benz. I pulled the cam covers on this lovely little 4.5 ltr V8 this evening to be absolutely astonished. That is absolutely the sweetest piece of machinery I've ever seen! Bearing in mind that this is a 29 year old car that sat in a field abandoned for well over 10 years, it is astonishing. While the exterior of the engine looked like it should have been in an abandoned farm tractor, the inside looked like an operating room! Not a trace of sludge, everything pristine and brand new in appearance. I almost want to get some transparent polystyrene cam covers made up just to show it off!!! So I did the next best thing. I dashed off into the house to grab the old digital and made some photos.

Needless to say, it has been a bit of a challenge to get clean. I EVEN DISCOVERED A LARGE BIRD'S NEST! It was nestled in behind the left headlamps in the crook of the feed cable for the lights. The car is now acceptable in appearance. I twice wet sanded the paint in order to get it reasonably level. (It got a "country" paint job full of dust, dirt and orange peel.) Compounded it three times and then buffed and buffed again. The one thing I can't seem to correct are the boot scuffs on the bumpers. I have tried and tried to polish them out but they are apparently just too deep. If someone will tell me how, I'll post some photos for the group's critique.

Thanks again to everyone, Eric in particular.

Earl Kiker
Houston