Starting Issue, 1974 280 SE

Hi Norbert,

Last week I started the 280 SE, the first time in 4 months. I had not driven it during this time because I put it up the back of the factory trying to forget how annoying this car has been! In the meantime I drove a car with L-Jetronic and K-Jetronic instead and life was good! No issues with those two.

Warmer weather is now on the way and I now have a little time to get back into this D-Jetronic project.

I firstly made sure the battery was fully charged. Of course I expected the engine to take 15 separate cranks to start, but this time I was astounded that it started first time! Although the idle was initially very rough, it eventually ran nicely on all 6 cylinders and drove fine.

My joy was short lived since its initial start after storage, since then, the car has gone back to its usual difficult starting, this morning taking 17 separate cranks of the key to fire.

The voltages at the ignition system and injection system are correct.

I read with interest about the R4. In fact, this possibility has also crossed my mind, I really hope the head is not cracked or has a failed head gasket. It's a really big job to remove the heads on these M110 engines. However the car is not consuming water.

I will consider my options over the next few days and advise. Thanks again for the replies Norbert.

Regards,

Carl.

Dear All,

After much effort it appears that I may have successfully fixed the starting issue on the M110 engine at last...... its been performing faultlessly since last Thursday. Let's hope it stays that way....

I cannot say for sure as to exactly what I did however! There were some items I attended to whilst I had components removed (Such as the camshaft cover and ignition distributor) and I'd lost patience with this car to the point where I was not going to waste more time on checking it started after each job.

1. Removed the camshaft cover (The valves were due for checking anyway) and checked the camshaft timing, it was correct.

2. Checked the valve clearances. One of the inlet valves had opened up 0.05mm. 4 of the 6 exhaust valves had closed very slightly, by 0.05mm. I corrected these figures of course.

3. Checked the head torque, nuts 1 +2 as per the tightening procedure in the workshop manual required retensioning. 3 of the camshaft assembly bolts required retensioning.

4. Replaced the spark plugs.

5. Removed the ignition distributor, cap and leads, checked and cleaned the leads and plug ends. Lubricated the distributor advance mechanism and checked operation, it was correct.

6. Cleaned the rotor, leads and cap (Polished the brass contacts). As these were 15,000kms old, replacement was deemed unnecessary.

7. Replaced the ignition points and set the dwell. Lubricated the cam.

8. Checked the dwell of the D-Jetronic points. I noticed that whilst the resistance was very low, the dwell of the points per side was asymmetric by 20 degrees. I could move the points enough in the housing to correct this figure (So the dwell was the same per side). Lubricated the cam.

9. Removed the air cleaner and housing. Blew out the air cleaner with compressed air. It was 15,000 kms old so replacement was deemed unnecessary.

10. Cleaned the throttle butterfly and housing, checked for any binding, adjusted throttle linkage and lubricated.

11. Removed wiring in the engine bay, cleaned connections, tested for continuity with D-Jetronic harness.

12. Removed D-Jetronic ECU, checked harness connections, cleaned board (Where the harness mates)

13. Checked engine bay sensors, all OK.

14. The earth connection from the battery to the chassis was not as tight as it should be. I removed the earth strap, cleaned the area and fitted two new "Star" washers to grip the metal.

15. Upon checking the alternator, one diode appears faulty although by 1,600 rpm the charging rate seems fine. I will attend to the alternator in the coming weeks.

16. Fitted the new battery I bought for it last year.


And so that was that! Would anyone like to have a guess at what the problem was? Perhaps it was a combination of a few items, I don't know.

I would like to thank you all for your help and encouragement, I was really over the car in the early part of the year I was ready to set it on fire!

Regards,

Carl.


Here's a little video of the first start after assembly:

vid115.photobucket.com/albums/n281/carl3...0896_zpsmsy4sko7.mp4


Some images of the work:

s115.photobucket.com/user/carl308888/med...jpg.html?sort=3&o=38

s115.photobucket.com/user/carl308888/med...jpg.html?sort=3&o=37


And.....finally back together:

s115.photobucket.com/user/carl308888/med...jpg.html?sort=3&o=11

Ji Carl,

great work! My guess would be the loose ground but that is speculation.

All's well that ends well !

Hi Carl, Great News, Congratulations!
You did the full check-up and the engine runs... and your car looks great!

I noticed you now havea little paint job left to do... shit happens!

One question remains:
I don't understand what you did with the trigger-points-set:

carl888 schrieb: ...
8. Checked the dwell of the D-Jetronic points. I noticed that whilst the resistance was very low, the dwell of the points per side was asymmetric by 20 degrees. I could move the points enough in the housing to correct this figure (So the dwell was the same per side). ...

My reading is you loosened the screws and moved the points-set to another position.
An offset of 20° seems to be much.

But - constructive the points are adjusted and fixed in position by the three latches of the sheet metal that carries them. The screws are not meant for adjusting them.

I don't remember I sent you the figure for producing the tool I constructed - but this would be the 'correct' way to adjust the trigger-points.
I could send you the ready-produced tool, too. Shipping rates are quite low for such light-weighted letters.

Regards
Norbert

Thanks Volker and Norbert!

I will drive the car over the weekend and see it it lets me down! I hope it is fine.

Norbert: Yes, I reversed into the garage door when I was moving the car from the factory, I was very annoyed, but I already fixed the dent this week now that my enthusiasm for the car has returned.

With regards to the dwell of the points, I am sorry but I do not have a photograph to show what I did. Let me try to explain however. The mounting of the points assembly is fixed in relation to the distributor shaft, but on my set, I noticed that the points were slightly off centre to the three latches. So I actually moved the points assembly in relation to the latches and simply measured the dwell with a multimeter. The initial reading was about 10 degrees difference on the distributor (20 degrees on the crank). I am really unsure if such an adjustment would make any difference to the running of the car, but I suppose I was keen to cover as many variables as possible.

I would love this tool that you have developed. Can I buy one?

Regards,

Carl.

carl888 schrieb: ...
I noticed that the points were slightly off centre to the three latches. So I actually moved the points assembly in relation to the latches and simply measured the dwell with a multimeter. The initial reading was about 10 degrees difference on the distributor (20 degrees on the crank). I am really unsure if such an adjustment would make any difference to the running of the car, but I suppose I was keen to cover as many variables as possible.

I would love this tool that you have developed. Can I buy one?
...

Hi Carl,
you had exactly the problem with the 'non-centered points' that lets one of the points fail a long time before the other side would do.
Even new points-sets are often not adjusted as exact as Bosch shold have done... I corrected the adjustment of some new points-sets during the last years.
But you are absolutely right - some difference between the point's adjustment will not make any remarkable difference in normal operation - as long as both open and close correctly.
The tool I developed let you adjust the gap to the original value - what means a maximum of reliabilty, because all possible tolerances are minimized.

I sent you a P.M. - shipped the tool to 'Down Under' once before.

Regards
Norbert