BMW 316 M10 Wont Start

mightymicra · March 27, 2017

Hiii,

Its been a very long time since I v last been here. I have came across a friend's car, A BMW 316 M10 (Carburetor) model. This car has been running ok and then was put to a garage where he wanted to do a carburetor swap. However things did not ended as planned and the car was sitting there with nothing and finally when he wanted it back the guy at the garage has said its not starting. My friend did not want to keep the car there anymore so we had to tow it back. Anyhow when we went there and asked the guy what might have been gone wrong he pointed some clip was broken in the distributor and this should be the problem. We towed it back to my place and then started to fix the broken clip. Still with no luck the car is not giving any spark. I was managed to get a workshop manual and checked the wiring and seems everything in order. This is a DCI model and there is a pulse generator in the distributor and my suspicion was this could be the problem. (The manual sates that if you remove the distributor assembly you might need to replace the signal plate "Which trigger the AC signal to the CDI").

So I know there are many experts with great knowledge in here and I would be glad if you could help me out with this to bring the beast back to life. (I am not an expert but trying to work my way up). So Thank you in advance to whole who can give me tips and ideas what should be done.

Cheers !!!!

Rumesh88 · March 27, 2017

Any idea what the clip the guy was referring to. According to a manual I have you can find two circlips - one at the bottom of the pulse generator assy which you cannot see and another on the top just below the dust guard. If one of them is broken then you cannot assemble the pulse generator.

If you have already checked the ignition voltage next thing is to check if the gap between trigger wheel (rotating part) and impulse generator (part attached to the base plate) is correct.

Rumesh88 · March 27, 2017

As for a place to find a spare distributor and for a check please search the forum or you may have to wait until someone else replies. If the plate is bent and the gap is incorrect (should be 0.3 to 0.7mm - smaller the gap the larger the signal) it may not trigger the ignition signal. What's the gap now? Is it way off the mark? BTW was the carb swap done?

Edited March 27, 2017 by Rumesh88

Rumesh88 · March 28, 2017

15 hours ago, mightymicra said:

Hii Rumesh,

Nop the carb swap was not done as that guy was just dragging the things and then the car was towed here. We are waiting to get it fired up so we can do the swap. So as you think this could be mainly the problem ryt ? I am not a great expert on these but climbing my way through interesting projects like these. Once again thank you very much for your help in this regard. appriciate it.

Cheers !!!

Appreciate your attitude. As for the issue in hand, check for ignition voltage at the CDI unit connector (hope you've done this already). Then connect a spark plug to the ignition coil output wire with plug body grounded to the chassis. Remove all spark plugs (to ease up cranking), crank the engine and observe the spark plug. Unless the trigger wheel gap is way off the mark or the CDI is packed up you should get a spark.

mightymicra · March 27, 2017

3 minutes ago, Rumesh88 said:

Any idea what the clip the guy was referring to. According to a manual I have you can find two circlips - one at the bottom of the pulse generator assy which you cannot see and another on the top just below the dust guard. If one of them is broken then you cannot assemble the pulse generator.

If you have already checked the ignition voltage next thing is to check if the gap between trigger wheel (rotating part) and impulse generator (part attached to the base plate) is correct.

Hiii.. Thank you for the reply. Yes I checked the resistance of the pulse generator coil and it seems to be correct. And the clip I mentioned is the one below the dust cover which leads to the CDI Unit. Yep also regarding the gap. The manual has mentioned you need to replace this plate if it was bent while dissembling. Seems to be that the plate is bent and the gaps are wrong. (Manual says 3mm gap). I cleaned all the parts (It was full of gunk) and before this when I cranked the AC voltage is between 0.5v - 0.7v and the manual state is should be 1.0v - 2.0v. . When I removed it and cleaned it and testing by rotating by hand it showed 1.0v - 1.2v ut it was quite fast I guess. When you put it back n when the engine cranks it bit slower and I guess this is the reason this does not generate the required voltage. Is there any place we can get the spare distributor and check ? Thank you in advance.

mightymicra · March 27, 2017

28 minutes ago, Rumesh88 said:

As for a place to find a spare distributor and for a check please search the forum or you may have to wait until someone else replies. If the plate is bent and the gap is incorrect (should be 0.3 to 0.7mm - smaller the gap the larger the signal) it may not trigger the ignition signal. What's the gap now? Is it way off the mark? BTW was the carb swap done?

Hii Rumesh,

Nop the carb swap was not done as that guy was just dragging the things and then the car was towed here. We are waiting to get it fired up so we can do the swap. So as you think this could be mainly the problem ryt ? I am not a great expert on these but climbing my way through interesting projects like these. Once again thank you very much for your help in this regard. appriciate it.

Cheers !!!

mightymicra · March 28, 2017

1 hour ago, Rumesh88 said:

Appreciate your attitude. As for the issue in hand, check for ignition voltage at the CDI unit connector (hope you've done this already). Then connect a spark plug to the ignition coil output wire with plug body grounded to the chassis. Remove all spark plugs (to ease up cranking), crank the engine and observe the spark plug. Unless the trigger wheel gap is way off the mark or the CDI is packed up you should get a spark.

Good Morning Rumesh,

First, Thank you for being so helpful in this regard. Yes I have already checked the connections and voltage for to the CDI and seems ok. And yes I did remove the plug wires and tested through the main lead (I forgot to take out the spark plugs and thank you for reminding me). There was a spark suddenly which ended up shocking me also . then nothing. When I was checking through the connections only wired thing I noticed was one pin connection from the CDI to the ignition coil was not the way it states. But if I were to change it seems a whole change in the wiring needed to be done. The surprising thing was the car was running in this setup before (assuming the garage guy did not mess with it) so I was not encouraged to change it. (I did not wanna burn the CDI, where I have no idea if that is fried already as well.). However I will be getting a distributor this week hopefully and will fix it and let you know the update. Thanx again..have a great day..and I wish to submit some pics so you will get the idea more clearly.

Cheers !!!