Just bought 67 250S - Will not start... - PeachParts Mercedes-Benz Forum

gisenberg · #1 12-20-2005, 04:07 PM

I just bought a 1967 250S from a widow. The husband had just bought it and it ran at the time. I know that he changed the fuel pump and it appears that he changed the plugs and wires. When I turn the key the engine just cranks. I checked that the fuel pump was working and gas is flowing. I also have sprayed starter fluid into the carbs and nothing happens. I found what I think may be the old plug wires in the trunk. I took some of the plugs off and put them back on just to make sure they are on ok. Every now and then the engine actually want to turn over, but thats about it. How can I check to make sure that their is spark for the engine to turn over?

Thanks for any help with this.

#2 12-20-2005, 04:55 PM

You can buy a spark checker from a mcparts store for about $10.00. If you don't have spark, I would make sure you have 12v going to the positive side of the coil, then I would check the point gap(about .016 inch/matchbook cover) and replace the condensor. I would first make absolutly SURE that the plug wires are correctly installed. If someone left the key on with engine off the coil/points/condenser(sic) could be fried. A 12v multi-meter can diagnose the problem. Also availible for cheap at mcparts store. Good luck. It's probably a simple problem.

gisenberg · #3 12-20-2005, 05:57 PM

Thanks for the reply. I will go get the meter. I am sort of a newbie at this. Is the Coil the item that has a plug wire from the distributor to the Coil?

The engine now spits once or twice during a 5 second crank when I spray starting fluid in. There was a puff of smoke that would come from the Carb. when it spits. In fact there was a flame once. Is that been I am getting a spark?

Thanks

300SDog · #4 12-20-2005, 06:30 PM

Or you can work the poorman's spark test holding an ignition wire (with rubber handled pliers) unscrewed from the plug resistor cap about 1/4" from the cyl head while somebody else cranks the engine. Spark between the wire and cyl head oughta be BLUE...... if it's orange then you've got ignition spark problems, could be internal corrosion of condernser or coil.

Lesser known fact: crummy condenser ($5 part) can prevent the venerable old 6cyl Haeckflosse/Benz from starting.

Mark DiSilvestro · #5 12-20-2005, 06:41 PM

Yes, that thing the center distributor wire connects to IS the coil. Most likely the 6 plug wires are mixed up. By now, it's possible repeated starting attempts have flooded it too, so you may need to remove and dry the plugs. While you're at it, you can connect a plug to each plug wire and check for spark - no need for a special tester. The firing order should be cast into the valve cover. You'll need to locate #1 plug position on the distributor. If no one's messed with the distributor position, there should be a little line or notch at the #1 plug position, visible on the distributor rim when you remove the cap. If the distributor position hasn't been changed, #1 cylinder is at top dead center on the compression stroke and the balancer timing mark is at top dead center, the distributor rotor should point to that notch.

Happy Motoring, Mark

#6 12-20-2005, 07:12 PM

The coil is a round top device that has one sparkplug
wire attached to it(going to the center of the distributer cap), along with a small wire going to the points in the distributer. The other small wire gets positive 12 volts when you turn the key on. If the car ran before and doesn't run now, try to trace backwards where peoples fingers were last.

It sounds like you may have spark. It may be too weak to fire the plugs due to a faulty points/condenser and/or a bad coil. Kepp in mind also, however, that the spark needs to happen at the right time in order for the engine to start. It sounds like the spark plug wires may not be connected in the right order if there was a set in the trunk. That would cause the spitting back through the carb., and a no start condition. The correct firing order is stamped on the valve cover. I was thinking, and you don't really need a meter to test the ignition system. Just a $3.00 12 volt test light.

Please be very careful using starting fluid. I blew a engine up once using starting fluid. Starting fluid car ruin your engine with little provocation. When I say "blew up" I mean it suffered internal damage. Instead of starting fluid try using a tablespoon or two of gasoline. If the air filter is off the car, you may have a flame shoot out of the carb if things aren't adjusted right. Keep the air cleaner on when trying to start unless you have a fire extinquisher handy. Let us know what questions you have and we will be glad to help.

gisenberg · #7 12-20-2005, 08:59 PM

Thanks alot guess for the great info and warnings. I have a feeling the plug wires are wrong for starters. I did take all of the plugs out and made sure the gap was correct. The plugs looked to be pretty new. There are 2 little clamps that hold the distributor cap on and I found that one of these clamps was not on and the cap was loose. If someone took the dist. cap off I am assuming from your information that the order may not be what is stamped. Is that correct? I will attempt some of your ideas tomorrow as it is pretty cold out and dark now. I have the car partly in the driveway as I had to pull it home and my driveway is sloped and the car to heavy for me and my friend to push by ourselves. We were trying to get is close to the garage but the chain that my friend was pulling me with slipped off when turning into the driveway, flew and punctured a pretty good hole in the corner of my radiator. So, now I have even another thing to fix.

When you say the order of the plugs are stamped is that under the long cap that the plugs are in? Please excuse my ignorance of terms, I am new to messing with cars, although I am finding it interesting and fun.

Thanks

gisenberg · #8 12-20-2005, 09:00 PM

Thanks alot guys....I can't spell!

Tomguy · #9 12-31-2005, 04:29 PM

4-wheel disc brakes. You'll probably need at least pads all around, possibly 4 new rotors and even calipers and rubber hoses. This is where it starts to get costly!

You may even need a new Master Cylinder and Brake Booster. I'm assuming you've checked the fluid level (full with NEW CLEAN FLUID) and bled the old crud and any air out of the lines.