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I tried brake bleeding the son's non-ABS 1988 245 today, a great opportunity for trying my new Power Bleeder for the first time. This car has an unknown service history, but luckily none of the valves were stuck. Only, the right rear opened, but no fluid came out. I unscrewed it completely, but still nothing. Three questions:
(1) Do I need a new caliper? Or is it just a matter of poking inside the valve openings with a suitable object to free it of whatever it is that's creating a blockage? (I should mention that the car brakes okay without any side pull, and both sides of the rotor are nice and shiny , so the caliper seems to be working as it should.)
(2) If I manage to free it up without removing it from the car, do I need to go through the whole bleeding process once again? The brakes feel firm now, after bleeding the other three calipers.
(3) The Bentley bleeding sequence puzzles me: LR, LF top, RF top, RR, RF both lower, LF both lower. The way I learned it in the old days was that you started with the one furthest away from the MC and worked your way towards it, like this: RR, LR, RF, LF. So I was taught wrong then?
BTW, the Power Bleeder was well worth its money, including postage to Norway. Recommended!
Thanks for any comments,
Erling.
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My 240 Page
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Thanks guys - the problem is now solved. I removed the valve, and opened it with a piece of string. As it had lost its protective cap, it was more or less filled with dirt. The dirt must have found its way further into the caliper as well, but a step on the pedal fixed that. After bleeding that circuit once again, everything seems to be fine.
A special thanks to Lucid for taking his time to explain the system; now it makes sense!
Erling.
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My 240 Page
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posted by
someone claiming to be roller
on
Sat Apr 23 10:56 CST 2005 [ RELATED]
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most likely you do not need a new rear caliper at that point, as it was already proposed ask someone hanging around to push a brake pedal . if that'll make no difference then you'd got some problem with the brake hydraulics: faulty master cylinder or tubes or caliper.
as i'd saw you page you do like your car, then it IS a good idea to do a bleeding process, to be on a safe side, unless you have some serious reason against.
regarding the bleeding sequence there is a very good comment by Lucid, indeed. you have to know how the brakes are(were) designed in each particular case if you wish to compare/estimate/criticize the bleeding sequence(s).
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With the bleeder open, but not removed, step on the brake pedal; the blockage will likely be removed, and fast.
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"The Bentley bleeding sequence puzzles me: LR, LF top, RF top, RR, RF both lower, LF both lower. The way I learned it in the old days was that you started with the one furthest away from the MC and worked your way towards it, like this: RR, LR, RF, LF. So I was taught wrong then?"
The Bentley (Volvo) sequence isn't all that different from the "old days", when you consider that the 240 has two separate hydraulic systems, the recommended sequence (below) simply bleeds each system separately.
On the front calipers, the upper two cylinders form an inverted "U", with a single bleeder at the highest point. The lower two cylinders form an upright "U", with bleeders at the two high points. The upper and lower cylinder pairs are each in a separate hydraulic system.
(See illustrations in Bentley, p 500-1 and Haynes, p 9-13)
Either A or B sequence can be done first (note that the starting point is farthest from the MC):
System A:
1) Left rear
2) Left front - Upper piston chambers (single bleeder, top)
3) Right front - Upper piston chambers (single bleeder, top)
System B:
4) Right rear
5) Right front - Lower piston chambers (inner and outer bleeders, either first)
6) Left front - Lower piston chambers (inner and outer bleeders, either first)
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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Try unscrewing the bleeder all the way out, and see if it's clogged, then either poke it out or grab a new one.
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-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '82 Mercedes 300SD for sale
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