Looks as though I'll put the clutch master back together and just drive it. The seals aren't cracked or frayed, just fluid leaked on the inside of the firewall and overtime the resovior ran dry.
FAG doesn't have any listing for the part numbers on my seals and the MB rebuild kit is too big. A new clutch master is around $130 bucks but I can imagine there will be a problem getting it to fit and I read somewhere that the slave would need to be replaced too.

The good news is the New ATE brake master cylinder came and it looks like it is the right one.
Question: Do I use DOT 3 or 4 in this old hybrid front disc rear drum beast? Is DOT 4 better for the seals in some way or just has a higher boiling point?

Thanks

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

I believe the main difference is the boiling point and you can substitute Dot 4 for Dot 3 but not the other way round. Another brake fluid related question - does anyone here have any opinions on using silicone / Dot 5 brake fluid in one of these old Finnies?

Happy Motoring, Mark

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DrDKW

"DOT #3 and DOT #4 brake fluids are made from Polyalkylene Glycol Ether which, by nature, has a very strong attraction to water (brake fluid is hygroscopic). Water contaminating brake fluid makes its boiling point drop which causes bubbles to form in the brake fluid (imagine sprinkling water into a frying pan full of hot oil). Bubbles and water are more compressible than brake fluid which makes it more difficult for the master cylinder to compress the brake fluid and in turn, compress the calipers and brake drums. A sign of this may be a low, soft, or spongy brake pedal feel (caused by the the contaminating bubbles and water compressing before the brake fluid does).

DOT #5 brake fluid, on the other hand, is formulated from silicone. While silicone is not hygroscopic and has a higher boiling point than DOT#3 and DOT #4 brake fluid, any water that gets into the brake system will sink to the lowest point of that system (water being heavier than silicone) and may potentially find its way to the calipers, boil at 212 degrees fahrenheit and cause a vapor lock which could cause brake failure. Additionally, DOT #5 brake fluid, being a synthetic, is much more expensive than DOT #3 and DOT #4 fluids, hence Tire Kingdom uses DOT #5 brake fluid only at the request of the customer."

Mark- this is from some thread I was reading earlier.

I think what I'll do about the clutch is just put it back together and then scavenge around in the yards or buy a new one if it gets really bad.

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

Well, it so happens that 'Miss Daisy' began pulling left while braking this week. She has the infamous 4 wheel drum brakes. I guess I shouldn't complain as, except for 1 rear brake hose, I haven't done anythng with them since I got the car almost two years ago. I've gotten used to the varying amounts of brake-chatter and self adjusters that sort-of work, but now I guess I'll have to pull the drums and hope it's just a lttle grease on the shoes as I haven't noticed any loss of brake fluid yet. I'll probably stick with DOT4 for now.

As for DOT5 / silicone, I'm using it in my infrequently driven '57 DKW. It's been in there for 6 years with no ill effects but I replaced all the brake hoses and wheel cylinder rubber when I got the car in '97.

Happy Motoring, Mark

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DrDKW

If you have the master or/or slave clutch cylinders out of the car and the rubber seals are OK, you might hone out the cylinders to remove any rust and put everything back together.

P E H

Thanks for the advice P E H,

That's the thing, the bore on the clutch master is in great shape and the seals don't look too bad, it just lost fluid over time and was wet on the inside of the firewall. I don't know what shape the slave is in.

I'm not going to hone it since psfred was avid about not doing that. There isn't any rust anyhow.

__________________
63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

DOT 5 isn't compatible with DOT 3 or 4, so unless you are doing considerable work and will be draining all the fluid anyway, or will be starting with dry system, it's difficult to change over.

It works fine, very little problem with boiling, but you DO have to flush periodically (and press the pads all the way back) to make SURE you don't have water in the system -- it will corrode the you-know-what out of steel brake parts, leading to ruined calipers and brake cylinders.

I stay with DOT 4 and flush ever couple years.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

As I suspected, the wheel bearing grease has liquified and is seeping through the grease seals. I'm hopefull it will clean up. Good news is that the late Elouise Powell seems to have had the wheel cylnders replaced at some time in the past 10 years. I'm sure she paid too much! Also, the self adjusters seem to be working normally (at least on the left front). I called around to several auto parts stores today and no one had the seals in stock, including Mercedes. Two seals are coming from Car-Quest tomorrow. They listed the seals for 220S through 1960, unlike some other parts stores that listed 'one size fits all - 1959 to 1971'. If not, I guess I'll be visiting the Mercedes dealer tomorrow. I will post the final results.

Happy Motoring, Mark

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DrDKW

Mark, this Car-Quest you speak of, it seems they have access to highly specialized parts (anything on a 40+ yr old being specialized)
Maybe they could get some seals for the clutch master?

__________________
63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

Car-Quest was, I believe, formerly known as Bap-Geon. I picked up the new grease seals this morning and they are of lighter construction than the originals but the dimensions appear to be the same. $4 each vs $20 each from Mercedes. I'm sure they'll work better than my leaky ones. The seals in question are grease seals for the front wheel hubs and probably fit other non-Mercedes applications so they aren't that hard to find. Clutch cylinder seals are probably a more specialized item so unless you could find a newer car that used the same type and size of cylinder or piston your search will be more difficult. The most common newer German car to use hydraulic clutch cylinders is BMW. Maybe something from a BMW 2002 or other model.

Happy Motoring, Mark

__________________
DrDKW

Well I just finished reassemnbling my left front brake. What a pain, nasty and messy!
Had to clean the shoes with alternating treatments of dish soap, scouring pad, hot water and Brakekleener. Test drove and it's back to normal (more or less). Guess I'll have to check the right side soon or expect a repeat performance of last week's braking excitement.
This will be my week for car repairs as my Honda also failed emmissions today.
I'll ask Paul at Car-Quest to see if there's any chance for vintage Mercedes clutch cylinder parts.

Happy Motoring, Mark

__________________
DrDKW

I woke up this thread from the archives because I'm going to be flushing my brake fluid this weekend..... using Valvoline Super-Synth DOT 4 fluid.

My plan is to start with furthest brake from the master cylinder, the right rear. Attach a hose and jar to the bleeder and pump away, never letting the MC run dry and closing the bleeder amidst brake pump after the fluid runs clear. Then I will just work my way around the car from furthest to closest to the master cylinder.

Are there any amidship bleeders at junctions along the lines?? Is 32 oz. of fluid (large bottle) enough to replenish the entire system?? And what about auto-shop bleeder kits, are they any good??

Any tips or tricks will be appreciated.

The car is a 1979 240D with fresh pads, partially seized rear calipre. Rotors are slightly grooved, but not horrible. Sometimes I have to take a 2nd stab at the pedal to build up pressure. Am hoping fresh fluid and NOT a master cylinder rebuild will solve my problems.

Are brake cylinders very expensive? Such as more expensive than a "normal" car? I am speaking relating to a finnie.
Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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I imagine they're still availible from Mercedes but very expensive. There're unlikely to be in stock at your local autoparts store. Have you asked Phil at Fastlane/MercedesShop or any other aftermarket import parts sources. You can try Hemmings (a monthly vintage cars & parts publication sold in magazine stores) and I see them turn up on Ebay. This is where buying a vintage car that's been driven (like my '60 Fintail), vs sitting, is a big advantage as there's less chance that the cylinder bore is hopelessly corroded. If the wheel cylinder bore is damaged, there are vintage car specialists that can re-sleeve them (check Hemmings). It's expensive but may be cheaper than a new one from Mercedes. If the old wheel cylinders are repairable, the good news is that the rubber repair kits are a standard size, still availible and relatively cheap. You may even find the same size kit in your local parts store that fits some American car.

Happy Motoring, Mark

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DrDKW

I've found that id they are rusted too deep and have to be honed too much, they still leak.

P E H