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#1
06-24-2012, 03:33 AM
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Another Vacuum question
I just bought an 87 300td. The brakes periodically will have no boost for the first minute or so the car is running or until I freak out and pump the living hell out of them. Then they're fine. The other day I had the brakes not there for me even after repeated pumping and furthermore the car would not turn off after killing the ignition...obviously vacuum failure. So my mechanic saw a hose that had come loose and plugged it back in and the car has been good for the last couple days. Then again today, trying to get brakes shortly after starting the car I had to pump it. I'm going to replace the original vacuum pump next week. Is that slow to boost vacuum pressure a pretty good sign that the thing is on the way out? Maybe I shouldn't drive the car at all until I'm able to have the pump replaced. Thanks in advance.
Seth 
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#2
06-24-2012, 08:24 AM
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I am not sure from you descritption if you have one or more problems.
When you do not have enough Vacuum you have Brakes but it takes abnormal amount of force to push down on the Pedal. The Pedal height is close to normal but you have what is tremed a Hard Pedal that takes a lot of force to push it down. With this amount of loss of Vacuum your Car will not shutoff. When the Master Cylinder goes bad and your Vacuum or Brake Booster is still good the effort to move the Pedal is normal or even easier. I this case the Pedal goes down further than normal of all the way to the Floor and you have little or no Brakes. Sometimes pumping restores some braking. A similar but less severe symptom to the Master Cylinder one can be caused by Air getting into the system if yo let your Brake Fluid level get low enough for air to be sucked into the Master Cylinder and then refilled it withoug bleeding the Master Cylinder. A sticking Caliper Piston/s can also make it seem like your Braking effort is increased a little. The symtom of that is your Wheel is getting abnormally Hot on a short trip and/or one Wheel is hotter than the rest. If it really is a Vacuum Issue I believe on your model there is still the Check Valve screwd into the Vacuum Pump Housing that can be removed and inspected for broken parts inside or clean out with WD-40 (don't use brake cleaner as I do not know if it harms the Plastic parts). The Brake Booster itself could be checked to see if it holds Vacuum. If you have been adding Brake Fluid and keep having to add it but there is no exterior leak it could be leaking into the Brake Booster.
__________________
84 300D, 82 Volvo 244Gl Diesel
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#3
06-24-2012, 08:47 AM
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If you can pump the brakes, it seems very unlikely that the problem is vacuum. Unboosted brakes can't be 'pumped'.
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1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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#5
06-25-2012, 07:43 PM
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Quote:
__________________
84 300D, 82 Volvo 244Gl Diesel
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#6
06-25-2012, 09:08 PM
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OK, OK so the pedal is rock hard. Is it on the floor, that is the pedal on the carpet or on the floor mat. If that is the case you have a hydraulic problem. Don't be dramatic, just tell us what the real symptoms are.
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Junqueyardjim Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis 1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA 2003 Jaguar Type X, AWD. beautiful, good mileage, Mom's car, but I won't let her drive it!
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#7
09-05-2012, 11:46 AM
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What was the final out come?
Charlie
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there were three HP ratings on the OM616... 1) Not much power 2) Even less power 3) Not nearly enough power!! 240D w/auto Anyone that thinks a 240D is slow drives too fast. 80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works
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#8
09-05-2012, 01:40 PM
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Quote:
The shutoff valve was replaced a few years ago and just as it developed a loss of brakes the engine takes a second to shut off but does shut off within a second or so but is different from instant shutoff that it had before the brakes went out. Now I am thinking more master cyl rather than brakes. Weird thig is that the brakes went soft in the fall when my dad drove it last in VA and the car was not driven until I shipped it to Ohio. The brakes were firm upon arrival and worked for a month when I got it and then went soft again last week. Any thoughts. M. CYL vs Vacuum Pump? Last edited by II Kings 9:20; 09-05-2012 at 02:03 PM.
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