230SL Hot Start Difficulty

[Pawel66]

Look, again, I am far from being really qualified for this, but, other than making sure that the speedo shaft is in one piece and properly lubricated, I calmed down my speedo by tightenieng the special nut on the gear box rear shaft. When this nut is loose, the speedo drive is not driven properly and this may be causing erratic speedo readings. This nut causes the speedo being driven just by its tightness.

It is described in the Technical Manual https://www.sl113.org/wiki/Electrical/Speedo#ErraticSpeedo

A lot is also described in the threads. I think someone (DrBenz?) desribed a simple test of this nut - to see if it is tightened - and again if I remember correctly, check it maybe - it was about sticking a flat screwdriver in the place where speedo shaft goes in the back of the gear box and try to turn it. If you can turn it - the nut is loose for sure. Please verify this.

I had very similar symptoms and the cause was this nut not being tight. I do not remember if I just had to remove flex disc to fix it or I did that when I had shaft removed. But I think if you have this big spanner for the sleeve nut, you can unscrew it and move the shaft backward to access the nut that needs to be tightened. Again, if I recall correctly, I did it 3 years ago.

[A Dalton]

  https://classicmotorsports.com/project-cars/1966-mercedes-benz-230-s/a-cheap-fix-for-our-transmission/

[Benz Dr.]

The slotted nut on the out put shaft on your tans is loose. This nut also tightens against the speedometer gear so that when it's loose the gear slips a bit. Your symptoms are classic loose output shaft nut.

[ja17]

With version III of the engine starting aids, both the CSV and injection pump starting solenoid operate at all temperatures. During hot starts it will function for one second only. If your problem comes back you may want to check the "one second relay".

Yes, most likely the transmission slotted nut.  We have a discussion on this forum of this fix also. It's always good t o hear from A Dalton also! If your lucky, just tightening the nut will solve your problems. If the transmission tends to have some minor shifting difficulties, more work may be required. Sometimes a key in a gear cluster will be damaged when the nut is left loose for a long period.

[ja17]

Here is one of our discussions on the loose slotted transmission nut.........

https://www.sl113.org/forums/index.php?topic=10281.msg70395#msg70395

[rgafitanu@gmail.com]

I cannot express how happy I am that someone as experienced as Joe or Radu kind of agrees with my suggestion! 

Thank you Pawel for the kind words. I am hardly experienced and definitely nowhere near Joe. I am a mechanical engineer and working on my cars became my passion. I have 4 MB's and I have been restoring my W111 for 3 1/2 years. I learned a lot from this forum and by doing it the wrong way so I am trying to share as much as possible. On a different note I come from the same part of the world as you and we have about the same age Pawel.

Radu

[Pawel66]

I have learned a lot from here too and it feels nice when sometimes you just get your view on cause of the issue right! Even more importantly thanks to this forum I know what I do not know much better than before...

66 was a good year! 

[Benz Dr.]

Everyone can learn about something here. The things I've learned here have been of great value to me and made some jobs easier to complete or understand.

 It's the combined knowledge of a lot people that's  key to the value of this site.

[Pawel66]

 It's the combined knowledge of a lot people that's  key to the value of this site.

Yes, I think this is the key point here...

[ja17]

I have also learned so much from everyone's experiences and knowledge. As long as you keep your mind open to new ideas, you can always learn !

[rgafitanu@gmail.com]

I only wish that the technical enthusiasm and passion of this forum would transmit to Pagoda's great-granddaughter R230 forums. I'm alone there.

[mistertj]

Erratic speedometer now fixed. The issue was as Joe Alexander highlighted. Just tightened that slotted nut and re-crimp the retaining lock plate. Only took about 6 hours, some of which was spent figuring where all the parts that fell out onto the floor needed to go. Thank you Pagoda SL Group for posting photos.

[Skippermitch]

 My 230 had hot start problems for a long while.  I hooked up an in car switch to bypass the thermo time switch just for cold starts.  Of course I cleaned and tested the CSV. Got a pop off tester and made sure the injectors were throwing a good pattern.  Still had hot start problems .... two plugs would get so rich they would not fire! As my car is an early 230 I pulled the connector on the 1 second time switch .... yep fixed the plug fouling problem and now at least I can run around without an embarrassing miss. I still have a miss on hot starts for 30 seconds or so, but no fouling. I'm real sure it is going to be the check valve cones in the IP.  I am going to pull them as my next project.  After getting the "fouling plugs" solved I took some shims out of the Baro-comp to richen up and she runs good once fuel gets through the check valves.  Might want to pull the 1 second switch and see if it helps. 

[mauro12]

Hi guys , i know it's been long time since you discussed about this topic but something is not very clear to me. The hard cold start depends from a malfunction on the cold start valve itself (solenoid or relays) , regarding the hot start , i've been told from the guy who rebuilt my injection pump that is mainly caused by a malfunction on the delivery valves on the injection pump. They tend to leak and they dont keep the ideal fuel pressure in the lines , this condition cause the hard hot start. You need to crank your engine many times before the ideal pressure is again obteined . Activating the cold start during hot start can cause the engine to flood .
i have the opposite condition , very good hot start and poor cold start , probably due to a defective relay.