El pronto help needed about 280C - PeachParts Mercedes-Benz Forum

ptoro01 · #1 10-23-2004, 09:30 PM

Hey everyone,

Help me out real quick. I have been searching through and trying to find if it was safe to drive with a stiff brake pedal. My buddy scott in cali is buying a 280c for under 500 and wants to drive it back home which is 250 miles away. The brake pedal is really stiff he says. I looked around and come up with one of the 2...the brake booster is gone or some vaccum line is throwing something off...

Please let me know so I can tell him where to start... Or is it safe to even drive it in this condition.

Thanks,
Peter

I dont much care if he makes it or not I just dont want him to rear end someone and wreck a brand new toy.

psfred · #2 10-23-2004, 10:04 PM

Some friend, you don't care if he makes it or not!!! (joking).

Hard pedal is either stuck brakes or a bad booster. Bad booster/lack of vac can quickly be tested by pushing down on the pedal repeatedly with the engine off. If it hisses a couple times and gets harder, the booster is working. If it doesn't change, the booster is shot or there is no vac due to a broken hose or something.

Broken hose will make it run badly.

Stuck brakes (high, hard pedal), will likely lock up and roast a rotor and caliper on the highway, to say nothing of not providing decent brakes.

Examine brakes before driving home -- most likely the pads are gone and the rotors are too thin (this seems to be a disease amongst 2nd and 3rd Benz owners, neglect the brakes). The result, of course, is stuck pistons and/or pads hitting the anti-rattle spring and hence producing next to no brake effect. My 280 was quite a shock when I got it running -- I had to STAND on the pedal to stop the car. Fronts were gone, pads on the springs, rotors worn to a taper, busted rear brake line.

Proper cure is a rebuild kit for all four calipers, new brake hoses all round, new pads and rotors, and new brake fluid if the booster is OK -- about $400 in parts, plus labor if he doesn't do it himself.

Have him check how well the car stops if he decides drive -- if they feel ineffective, they must be fixed before traveling.

Peter

300SDog · #3 10-24-2004, 02:34 AM

Sounds like a bad vacuum pump if power brakes arent working. If the pads were shot and/or the rotors warped you'd hear them grinding or the car would come to a wobbling stop. When calipres freeze the car usually pulls to one side or the other. Sometimes just moving the calipre pistons while changing brake pads is enough to free up sticky calipres.

Is it safe with manual brakes for merely 250 miles on mostly highway driving?? That depends on the skill of the driver more than anything else. Some people need the best brakes they can get or the roads arent safe for them at all.

Am constantly getting morons tail-gating too close behind me. Occasionally I like to stop short at red lights just to hear their tires screech when the idiots jump on their brakes to avoid rear-ending my 240D.

Sorry, but I've got no sympathy for people who constantly rely on their brakes to correct errors when they drive. If your pal is cautious and maintains a safe following distance, there should be no problem.

Flush the fluid and bleed the hydraulics when the car gets home. Plus take a look at the vacuum pump, disconnect the main line to see if the pump sucks.

$500 is a pretty good deal for the twincam 280C. It sounds like a terrific car!! If memory serves me well and its an earlier version of 114, you might find the vacuum pump on the front of the camshaft carrier.

ptoro01 · #4 10-24-2004, 06:32 PM

Thank you for the diagnostics. I have forwarded him the info and if he makes it home alive then he will most likely say hi in the vintage section as well. 6cdnmbz is the wreckless kid that attempted to drive 250 miles without good brakes or plates, lets see in a few hours if he makes it or if he gets a visit with big bubba.

THanks.
Peter

6cndmbz · #5 10-25-2004, 12:09 AM

Haha, I am the foolish kid that drove the car home with no plates. It was a disconnected (yes, disconnected) brake booster line. Both that and the other line like it that goes to the intake manifold were disconnected from the engine. It had brakes, but blew copious amounts of smoke and idles so badly it stalls unless you keep one foot on the gas when braking. I'm now wondering if those lines were disconnected for a reason, cause I don't think it was smoking that badly before I reconnected them.

THE MORAL: NEVER EVER EVER BUY A MERCEDES FOR $400 AND EXPECT IT TO RUN OK FOR MORE THAN 5 MINUTES.

I guess I gotta go figure out if the car is fixable or scrap.
BTW it was loosing oil like crazy (obviously) to make my James Bond Smokescreen.

psfred · #6 10-25-2004, 12:24 AM

Used a lot of oil, eh?

If you are lucky, just bad valve guides, but I'm betting worn out rings.

Only way to tell is take the head off, BUT, if it was severely overheated, the tension may have gone in the oil control rings, this makes it burn oil badly.

If the smoke was white and smells like a smoldering candle wick, change the modulator on the transmission, it's blown and you are sucking up tranny fluid. This will ruin the engine, so you want to fix it. If this has been going on for a while, it just may be that it will get better as you burn the carbon out.

I'd also check to make sure no one "fixed" the crankcase ventilation system by substituting a hose without the proper restriction or valve in it -- it will run OK if you then set the carb rich, but will suck enough air through the crankcase to carry considerable oil with it.

Don't laugh, I've seen plenty of strange "idiot fixes" in my life, including vacuum lines to emissions controls cut and plugged on the "dead" side -- engine side left open. Lots of complaints about how crappy the engine ran with the emissions stuff "disconnected", too! Engine had a double handfull of mud (literally) in the crankcase....

Peter

6cndmbz · #7 10-25-2004, 01:37 AM

Hehehe.....alright....well here's the thing. When I bought the car, the guy said the brakes were stiff. I drove it and they had no power assist. I was like, fine, I'll spring for a brake booster. I bought the car cause I needed to get home (250mi) and had no ride, and for $400 I figured it would be entertaining. I saw very little smoke.

The next moring, I surveyed the damage. In the engine bay, there were two large lines, one from the booster sitting on the engine with plastic baggies taped over them. I reconnected them and the brakes work. I think it may be leaking through the vacuum pump.

Then again, the car has so many problems, I could be wrong. BTW, it smokes on startup, smokes sometimes while accelerating, and smokes sometimes for the hell of it. I made it home, its sitting in the parking lot and I have yet to mess with it. If its internal engine related, I'm gonna have to sell it (likely to a junkyard). I wanna restore it, but I wouldn't be able to afford engine rebuilds.

ctaylor738 · #8 10-25-2004, 09:23 AM

You may have a bad diaphragm in the vacuum booster pump (front of engine). That will make smoke like crazy. You can rebuild it for less than $30. Test it by connecting the intake manifold directly to the brake booster and see if it still smokes.