What year? I'll guess it's the one with all the buttons, in which case--sure. Along with a slew of other stuff. Here's a nice link: http://modtech.us/downloads/Merc.zip, it's a shop manual copy. You'll learn about the Rube Goldberg mess'o electro-pneumatic confusion MB is so fond of. A handful of vacuum dashpots connected to a bunch of flaps by a tangle of vacuum lines controlled by analog electronics interpreting signals from a grab-bag of sensors (and not just temp sensors). The last sentence is simple & elegant compared to MB's "climate control" system.
On the plus side, the "temperature unit" is really easy to get to--unscrew the two philipshead screws at the bottom of the woodgrain trim, pull the knob off the fan speed switch, and pull the trim off. Then simply pull out the black box with the buttons--it's held in with spring clips (no screws), just wiggle it out, pull off the two harness connectors, and, if you want to play with the guts, the box comes apart easily enough. Good luck.
OK, sorry about the MB-bashing. Here's what to check for first. Open the hood. If you;re not familiar with MBs, the hood could be lifted into vertical position, making life easier. Look at the lift cylinder on the right side of the hood, there's a stainless steel wire spring clip--pull it back, and lift the hood into vertical position. Now, take off the plastic debris screen over the blower motor, between the firewalls at the backof the engine bay. You have to pull off the rubber trim around it, and take out 4 self-tapping screws/bolts (you'll see them), and wiggle the whole thing out. Try not to flex it too much--the old plastic could be really easy to crack. On the passenger side, attached to the metal coolant pipe, you'll see the vacuum pot that controls the coolant flow to the heater core. Disconnect its vacuum line & start the engine.
Is the coolant pipe hot?
Is there vacuum on the line which you pulled off? (you should feel it by putting your finger over the hole)
See if the vacuum pot works--attach a chunk of vacuum line to it, and either a) suck on the line b) get a 5cc "drain syringe" at a pharmacy (just tell them what you're using it for, it's perfectly legal to sell them, they don't have needles--just a plastic barrel & plunger), push it down, connect it to the vacuum line & pull on the plunger to create vacuum, or c) connect the pot directly to manifold vacuum. Does the heat stop blowing?
SlumBenz, tried all that.Coolant pipe was hot as hell, checked all vacuum lines. Still blowing hot air. What next???? Could the thermostat have anything to do with that? Really lost at this pont. I just did not take apart the center console yet, or glove box. Help!!!!
OK, not quite sure what you're saying, i guess i wasn't too clear myself. So here we go:
With the engine hot (and blower going in the car), pull the vacuum hose of the dashpot on the coolant line. connect a length of (a couple of feet, ~ $0.50 at a parts store) vacuum line to the dashpot. Now apply vacuum to that line (any way you want, from sucking on the line to a syringe to connecting it straight to manifold vacuum). Wait a minute or so. The air should be blowing cold now, and the pipe should be cooled down quite a bit. IF NOT->bad "Vacuum heater valve element", replace. If the air's cold, the problem is elsewhere, but, at least, you can shut off the heat by connecting a vacuum line directly to the manifold. And no, can't be the thermostat. 'luck.
Err - there we go - the director's cut version! BTW, if you're in some pleasantly warm climate, pinching off the rubber hose (in the engine compartment, the one which leads to the steel pipe & heater core) will shut off the heat. Very crude, but (almost) foolproof.
Drove my car all day approx 75 miles. Turned off engine for about 5 mins. when i went to start the car, it started then stallled, everytime it started the car just died. Its just not holding idle. it's a 1987 190E 2.6. Been running great except for the heat problem blowing all the time. I need it to keep idle so i can work on the other problems. Checked forum could not find a solution to my kind of problem. Please help. Thanks
Look for vacuum leaks, any vacuum hoses you may have forgotten to reattach/inadvertently knocked around. If you can start the motor, have someone sit in the driver's seat to keep it from stalling, and, with the air cleaner off, spray some carb cleaner at suspect places around the intake manifold. If the engine picks up revs while you're spraying some area, that's where the air leak is. Isolate & fix.
Thanks SlumBenz you are getting to be my new best friend. I had the air cleaner off today checked all lines they seemed to be ok. In the process the air cleaner housing (lack of a better word) washers sealed themselves to the engine ,both of them. LOL now it just sits there. But my bigest problem now is still trying to make it hold idle. I will try your method and give results.
Also, my OVP fuse(10 amp) keeps blowing out which triggers the ABS light to come on. Want more? Oil light on dash stays on, can't unscrew some of the spark plug wires. Enough for now.
Can the no idle be connected to maybe the fuel filter? It revs great as long as i hold the accelerator pedal down once i get off the gas it dies. Amen
Got a deadline 2 hours ago, will answer the whole thing later, but don't run the motor unless you're *sure* you've got oil pressure... not sure if you're talking about oil level light. Will answer in a few hours. That pesky work $h1t.
SlumBenz, Tried the carb cleaner no vacuum leaks. After pondering the whole problem,finally got under the car to locate fuel filter, after shaking it a few times got back in car, It started and is holding idle peering like a kitten. Guess I need a new fuel filter. Now back to major problems.
Glad it was something as simple as the filter - in all of my life, i've never seen a filter make the car idle badly on fuel injected cars, but hey - proof's in the puddin'. You're also in the ~5% who own 20+ yr-old Mercs without vacuum leaks. Mercedes is really confident of their intestine-shaped rubber is an elegant way to plumb their cars. Misplaced confidence--the rubber dries up & turns brittle, as you;ve found out taking off the air cleaner. If you know of a friendly junkyard in your area, someplace which lets you go in with a toolbox, poke around in cars & take off whatever you need, go there and spend some time looking at mercs in various stages of disassembly. You'll not only get all the "dealer-only" parts for pennies on the dollar, but get to learn a whole bunch about your car without having to rip it apart. Hint: No matter how sleazy-seeming the place may be, put everything you grab, down to the nuts & washers, into a separate box & show it to the guy at the counter when you pay. Not 'coz "stealing is wrong", but because you'll get a way-better price & a smile from the 300-pound guy behind the counter.
Oil pressure: yours is dangerously low-- the gauge should be pegged from the moment you start your engine, unless you've been sitting in traffic on a 95+ degree day. Drive your car, jack it up, and change your oil & filter with cheap 20-50. Drain your oil into a clean tray (buy a cheapo one at the parts store - should cost less than $5. Stick a clean magnet into it, and drag it around on the bottom. Check for metal flakes bigger than fuzz. Let the pan sit while you refill the oil & put on a new filter (if you pressure-washed your engine at a self-service carwash with those "don't even think of washing your engine" signs, you're ahead of the game), and, without shaking it too much, poor the oil out into either the oil bottles you;ve just used (requires a $1 funnel) or plastic coolant/laundry detergent jugs (cut a plastic coke bottle in half for an instant funnel). Look at what's left at the bottom, drag your finger through it. Any shiny flakes? a few teeny-tiny sparkles is OK, flakes you can see=>disintegrating bearings. This stuff is aluminum or babbitt, non-magnetic stuff, meaning your bearings are going. Any oil color other than almost-black or amber, in other words brown or even malt-shake white, is a sign of water (or coolant) in the oil - bad 'cos that means that your oil pump is trying to suck foam, the frothy oil-water suspension that picks up tons of air as it's whipped up by your engine. Sign of a bad head gasket at worst, (in which case the oil cap will have that malt-shake foam on it), to something simple like a bad breather or an engine which sat unused in cold weather. Anyhow, see if the oil pressure gets up to normal with the new oil-filter. If not, get ready for a motor rebuild.
P.S. If you don't read the manual before changing out the filter, expect to get sprayed with some gas. Have a bunch of rags and even (gasp) a disposable Halon fire extinguisher (those come in big spray-can size, and having one could have saved me two cars. Technically, they're not ideal, but thy do a whole bunch of cooling on top of cooking out the oxygen--meaning you can spray the stuff on people - and it's cheap.
Almost all gas is full of (up to 10%, i think it's some eco law in the states, at least in MA) ethanol (alcohol), which is hydrophilic, so it's unlikely you have water in your gas, so don't waste your money on Drygas.
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