Changing points and condensor '75 450SL
 

1975 450 SL Started this AM and ran for a couple of minutes then began to stumble, then died. Then would not start. When I pulled the dist. cap I have a condensor that looks like it had a wire attached but no wire there. I can't see where it should be attached. When searching on line I can find points but no mention of a condensor. The number on the condensor is Germany 1 237 330 293 533. Looks like there was a wire soldered to it but can't find one in the distrubitor. Help! Leont

Condensor was cut out apparently not needed. I assume it is controlled by the module. Have so far changed the cap, points and pulled the distributor out and cleaned it along with the trigger points, they looked ok. I am now in the process of changing the auxiliary air valve which was stuck and when trying to clean it I broke it and am awaiting another. Fuel pump was replaced. When I pulled the distributor I noticed that the vacume advance plate had scratch marks under 2 of the things that hold it in and it wouldn't move. I loosened them and got it to move. Not sure what this will do since I can't try it until I get the part in. Will let you know. Leont

Just changed out the auxiliary air valve and that wasn't it. Starts then dies immediately. Not sure if this helps anyone but will keep posting. Anyone have a comment? Thanks, Leont

have you checked the fuel pump relay. They can run the pump long enough to start then malfunction in the run mode

Thanks for the response, will check that if I can find the fuel pump relay. I think it is under the passenger side dash. I have seen the relays there but haven't, as yet found which was which. We just picked up a couple of my great-grand-sons for a week stay so may not get a lot done for a day or two, Ha! Thanks again.

Pulled no. 1 plug to confirm I was at TDC and it was fouled with carbon. Apparently with all I was doing I had fouled the plugs. It started and is now running. Will have to take it out tomorrow and see what it does. Don't have a timing light to set the dwell so will have to either get one or take it down to the local shop. I am trying to do most of the work myself both to save money and just to say I did it. Well my grand-daughters husband was racing but not with mercedes, but he helped. Will let you know.

Didn't work. Pulled distributor and cleaned it and replaced the plugs. Now starts but I can't get it to idle down. Don't have a timing light so will have to take it to someone I guess. Not sure if I can ever get this neat looking little car to run right. Any help would be appreciated.

Pulled the breather off and looked for leaks in vacuum lines and put the breather back. Now won't start! It is an intermittent problem that is driving me crazy. Really didn't change any thing then it wouldn't start. Can any one offer any things?

Some where while changing things I crossed up #5 and #6 plug wires. Now running. Have a dwell meter and it is a 30 but don't have a timing light so will have to take it to someone to get it timed. Runs ok but seems to lack power, also running near 200 deg. Hope it is timing but aux fan doesn't come on, looks like someone cut a wire that leads to it.?? Well at least it is running.

might try trial and error with the timing. just mark your starting point. I don't know if they have them for a Mercedes, but on my last car that had points. A 69 Lincoln Mark 3. They have what they call electronic points/ignition. Anyway, there's was no setting a gap and I never replaced points again. so for you who have cars with the mechanical points, you might check to see if the electronic is available for your old Merc when you go to replace them. they are great

Thanks for the response. I plan to take it in and get them to put a timing light on it. That will just cost $20 they told me. It also seems to not have as power also, which I assume could be timing also. Will post after that. May need to change the thermostat, will see. Thanks again. Leont

when you pulled the plug was the piston at the top of the cylinder when the timing indicator was at tdc? the temperature gauge sensor, fan clutches can cause over heating too. if the timing chain jumps a tooth that can cause over heating and lack of power.

Yes. Mark was at 0 and had my grandson turn the engine while I had my finger over the hole, so sure that was right. Hope to get the timing checked tomorrow will let you know. Thanks again.

you can look for vacuum leaks by spraying carburetor cleaner or starting fluid around the vacuum hoses with the car running and look for a change in the idle. don't smoke. did you check to see if the vacuum advance is working and see if that vacuum line is ok?

Timing checked out ok at TDC with the light. Changed out the thermostat to no avail. Would a vacuum leak cause it to run hot? Don't smoke,(Respiratory Therapist) Will check for leaks. Power has decreased also but starts right up even when hot. Thanks for the input. Leont

maybe multiple issues. start with the most common and easiest to fix of running issues. that being vacuum. check the vacuum advance diaphragm on the distributor. make sure there is vacuum at the distributor, then disconnect the distributor vacuum line at the source and suck on it. you should not be able to pull any air through the diaphragm on the distributor. you did replace the rotor when you replaced the cap? need to fix running issue first, because it may very well be the cause of the over heating. but holy smoke, I looked up the cost of a fan clutch for the 75 107. OUCH!

Brookings, Was in a thrift store in Memphis, Tn. the other day and found a new timing light, cheap! Checked the timing myself just to see if it worked and I think my local mechanic was off. He must have been looking at what he thought was O but was actually a hole. It was closer to 20. I set it at TDC and it is running great. Only problem is the overheating. I now think it must be the water pump. I flushed the radiator and also pulled the top hose off and started the motor (it was warm enough to open the thermostat) very little flow. Will remove the water pump when it cools down, 108 here in Ar. right now. Hope all this helps someone and again thanks for your input. Need a vacuum gauge now.

By the way I did change the rotor and sucked on the vacuum advance and couldn't move it. When I pulled the dist. out earlier I had to free up the vacuum advance plate and lightly lubed it so it would move freely. Thanks again.

the impeller could be loose on the water pump alright, but rare. when you flushed the radiator, did you run the flush through your block too, flushing the whole system? the temperature gauge sensor could possibly be bad. those are usually under $20. My overheating problem on my 129 turned out to be the fan clutch. I looked at yours at autohausaz.com and it was about $400. I'm lost for answers if it's not one of these issues. Good luck!

Put a new water pump on and has new thermostat. Still running hot, around 200 but it is 85 to 90 today. Now it is surging when I first start it, it stops after a couple of minutes, think it is a separate issue. Idles at about 1500 and can't adjust it down. May be a problem in the cold start valve, think it is leaking. Have to get some parts for my daughters car tomorrow so will have to wait on this one. Thanks again for your input.