'75 240D starter? problem
 

I'm working on a 75 240D with the separate ignition switch and starter switch (salt shaker glow plug indicator). I cannot get the starter to turn over the engine. Battery is new, correct for car and fully charged. I've replaced the starter and it had no effect. The glow plug indicator will glow but when I pull the switch to the start position, all lights and indicators go out. I've hooked up a remote starter switch to the + battery terminal and the small starter electrical connection and can hear the solonoid clicking on and off, but the engine still doesn't turn. I can turn over the engine manually (I jacked up a rear wheel, put the transmission in 4th and turned the wheel, which turned the engine.)

The problem started intermittantly. The car would be turned off and a few minutes later would not start. We would wait awhile and then it would start. Now it doesn't start at all.

I'm now at a loss for ideas......Any suggestions? Thanks!
Scotty

hit the starter once or twice with a hammer and then try it. My W115 240D needed the hammer periodically. After the starter got the hammer, it usually behaved for a good 6 weeks more.

I had an old Chevy that would do the same thing when it after running on the road for an hour or more. Turned out to be heat related, and a new starter solenoid fixed it right up.

I had a similar problem with the W115 300D. Check the relays on the left side intake manifold that are on that silly bracket.

If you try to jump the starter by touching it with power does it crank?

Thanks for the suggestions. The hammer was the first try, a new starter and solenoid was the second try. No luck with either. I have power to the starter and can short between the small post (that should be activated with the starter switch) and the larger post (that is wired directly to the positive side of the battery). I get spark and the solenoid clicks, but it will not spin. I have not tried literally running a jumper cable from the positive post to the starter, but I will.

I think I see the relay Diametricalbenz mensions, is it the one on the firewall, under a couple fuse blocks? What does it do and how do I check it? Thanks for your help!
Scotty

the car has a gorilla knob?
yes?

the cable that comes from the knob down along the steering column can get out of adjustment or the rubber isolation blocks can be shot. either way it may prevent the switch from making contact. so no power will go to the starter.

follow the cable down to where the business end is and see if all is in proper alignment. ect.

good luck

tom w

It should have the gorilla knob if it's a 75'.

If the starter won't spin by jumping it from the terminals on the starter itself it might be a solenoid problem. But give it a jump from the battery and see if it cranks.

There should be a relay under those fuse blocks as you pointed out but that was the culprit on the W115 300D so it might be different.

The car does have a gorilla knob, so I will check that.

I pulled the starter out of the car again and hooked it to to the car's battery with jumper cables. With no load it worked fine. It is looking like an electrical connection somewhere. I have to work today, so I will be tracing wires and cleaning connections tommorow. I still haven't looked at that relay either.
Scotty

Some info
 

I have had trouble with my 240D not starting a couple times. Most recently I had to replace the solenoid, which was nice because I didn't have to pull the starter and I could do it from the topside (who needs a turbo, anyway).

I also had trouble with the relay - either the contacts were bad, or it wasn't pulling in all the way, I don't remember. I was able to pull the relay guts out of the metal housing and push down on the contacts and get it to start. The gorilla knob must be in the run position, and the car MUST BE IN PARK. You will be defeating the failsafe, it will start in Drive. Don't ask. I ended up replacing it with a $2 generic relay, instead of the $100+ Bosch version.

Speaking of which, electrically, there are the key switch, the knob switch, and the Park/Neutral switch that all have to be made up in order to pull in that starter relay. So a problem with any one of them won't let you start.

The purpose of that relay is to cut out the AC compressor during starting.

i had this exact problem on my 240d. It is your ground, it can support 30 amps but not 150 check it, pull the battery. I replaced it with 0/1 ga b/c i love overkill. :Peace!:

It Lives!!!
 

Finally got it started! It was one of the battery connections. I cleaned all connections to and from both terminals. None of the connections looked terrible, but the positive terminal looked a little rough so I replaced it and there was a little oil between the negative cable and the block connection point.

Another possible culprit was the wheel bearing grease I was using to prevent corrosion on the battery posts. I got the idea on this forum a couple months ago. Now I am thinking that when it heated up it got between the posts and the terminals and increased the resistance to the point where the car wouldn't start.

Anyway, Thanks to all who offered suggestions! They really helped!

Scotty