'72 Mercedes 250 spark problem - Mercedes-Benz Forum

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old 10-11-2009, 06:55 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Oct 2009
Posts: 14
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
'72 Mercedes 250 spark problem

I am trying to fix an intermittant spark problem on a friend's '72 Mercedes 250. In the last month, the car has quit twice while driving and found to have no spark at that time. After both stalling episodes, the car restarted a few hours later. Now that the car is sitting in my shop, somedays it starts just fine and other days it does not start and is found to have no spark.

It has a Perma-tune unit that appears to be an add-on to the original ignition system. I am not familiar with these units but assume that it's function is to enhance the spark. Do these units have a history of problems with intermittant spark? Is there electronic ignition conversion units available for this car? I have obtained an original wiring diagram, with the thought of eliminating the Perma-tune unit and returning the ignition wiring back to the stock configaration, but I don't know if this is the best way to go. Can somebody point me in the right direction as to fix the spark problem in the best manner? I appreciate any help on this. Thanks in advance.
sp1249 is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 10-11-2009, 10:23 AM
Lifetime Premium Member
 
Scoot's Avatar
 
Date registered: Oct 2002
Vehicle: 1967 250 SL, 1963 220Sb
Location: Los Angeles / Altadena
Posts: 2,591
Mentioned: 3 Post(s)
Quoted: 103 Post(s)
Lifetime Premium Member
Hmmmm. I don't know if my experience is related or not. I have the Petronix electronic ignition thing inside the distributor. One nasty problem with it is that if you leave the key on without the engine running for a few hours it will fry the unit. I don't know how long you can leave it on without frying stuff, I am not going to find out either.

Currently: 1967 250 SL, 1963 220Sb, 1965 300SE Lang, 1971 280SE parts car, 1972 Alfa GTV, 1965 Alfa Duetto, 1993 BMW R100R
Past: 1971 250 C, 1985 300 TD, 1967 250 S, 1968 280 S,1981 300 D, 1982 280CE, 3 Facel Vegas, Borgward Isabella Coupe, Alfa 2600 Sprint, Volvo P1900 (yes), numerous less interesting Volvos, ...
Scoot is offline  
post #3 of 12 (permalink) Old 10-11-2009, 08:58 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Oct 2009
Posts: 14
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
'72 Mercedes 250 spark problem

The key wasn't left on or anything like that. The Perma-tune unit on this 250 actually uses the original type points. Sounds like the Petronix unit is a true electronic ignition? (that is, without using points?)

Last edited by sp1249; 10-11-2009 at 09:01 PM.
sp1249 is offline  
post #4 of 12 (permalink) Old 10-11-2009, 09:19 PM
BenzWorld Elite
 
Grubeguy's Avatar
 
Date registered: Jan 2006
Vehicle: 73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
Location: DC Area
Posts: 2,110
Mentioned: 1 Post(s)
Quoted: 97 Post(s)
Send a message via MSN to Grubeguy Send a message via Yahoo to Grubeguy
I would highly suggest a Pertronix unit - I have one for my 108 and it runs a LOT better than with the normal setup... Not TOO expensive, and it might solve your problem.

Try this - with the engine running, tap on wires and connections, and the coil. If the engine runs differently, stalls or sputters, your problem could be there.

Good luck!
Grubeguy is offline  
post #5 of 12 (permalink) Old 10-11-2009, 09:32 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Oct 2009
Posts: 14
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
'72 Mercedes 250 spark problem

Thanks, I appreciate the info. I will be looking into getting a Pertronix unit for my friend's 250.
sp1249 is offline  
post #6 of 12 (permalink) Old 10-12-2009, 06:23 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Oct 2009
Posts: 14
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
'72 Mercedes 250 spark problem

Just found out that Pertronix does not make an ignition unit for a '72 Mercedes 250. Don't really know if I should get a replacement Perma-tune unit like what is on there or to eliminate it altogether and return it to the stock ignition configaration. Hoping somebody can point me in the right direction and give me some ideas on what is the best way to get some spark for this 250.
sp1249 is offline  
post #7 of 12 (permalink) Old 10-12-2009, 07:31 PM
BenzWorld Elite
 
flyboyike's Avatar
 
Date registered: May 2003
Vehicle: 2012 Focus SE
Location: Ormond Beach, FL
Posts: 7,699
Mentioned: 1 Post(s)
Quoted: 68 Post(s)
Quote:
Originally Posted by sp1249 View Post
I am trying to fix an intermittant spark problem on a friend's '72 Mercedes 250. In the last month, the car has quit twice while driving and found to have no spark at that time. After both stalling episodes, the car restarted a few hours later. Now that the car is sitting in my shop, somedays it starts just fine and other days it does not start and is found to have no spark.

It has a Perma-tune unit that appears to be an add-on to the original ignition system. I am not familiar with these units but assume that it's function is to enhance the spark. Do these units have a history of problems with intermittant spark? Is there electronic ignition conversion units available for this car? I have obtained an original wiring diagram, with the thought of eliminating the Perma-tune unit and returning the ignition wiring back to the stock configaration, but I don't know if this is the best way to go. Can somebody point me in the right direction as to fix the spark problem in the best manner? I appreciate any help on this. Thanks in advance.
You have checked the cap, rotor and coil and they're all OK, right?

Felicita e un bicchiere di vino con un panino.
flyboyike is offline  
post #8 of 12 (permalink) Old 10-12-2009, 07:37 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Oct 2009
Posts: 14
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
'72 Mercedes 250 spark problem

Yes, all those items were replaced about a 1000 miles ago with Bosch components.
sp1249 is offline  
post #9 of 12 (permalink) Old 10-13-2009, 11:23 AM
BenzWorld Elite
 
Grubeguy's Avatar
 
Date registered: Jan 2006
Vehicle: 73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
Location: DC Area
Posts: 2,110
Mentioned: 1 Post(s)
Quoted: 97 Post(s)
Send a message via MSN to Grubeguy Send a message via Yahoo to Grubeguy
Help me out here - the 250 and 280's engine differ by displacement, and little else, right? Pertronix makes a unit for the 280s...
Grubeguy is offline  
post #10 of 12 (permalink) Old 10-13-2009, 04:56 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Oct 2009
Posts: 14
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
'72 Mercedes 250 spark problem

Unfortunately, Pertronix does not make a unit for a '72 250. They did not have my application in their catalog, so I emailed them with the distributor number and they responded back with a "Not Available". Are there any 250 owners out there that have an aftermarket ignition that could let me know what they are using?
Thanks
sp1249 is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > General Mercedes-Benz Forums > Vintage Mercedes-Benz

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
     
    Thread Tools
    Show Printable Version Show Printable Version
    Email this Page Email this Page
    Display Modes
    Linear Mode Linear Mode



    Similar Threads
    Topic Author Forum Replies Last Post
    72 Mercedes 250 ignition problem Bismark Vintage Mercedes-Benz 2 01-22-2008 01:38 PM
    Mercedes C 250 D master888 General Mercedes-Benz 0 10-08-2004 02:30 PM
    Mercedes C 250 D master888 W202 C-Class 0 10-08-2004 02:29 PM
    Mercedes 250 S 1973 Miguel Vintage Mercedes-Benz 3 09-01-2004 09:47 AM
    Mercedes 250 123series lemmyb W123 E,CE,D,CD,TD,TE Class 5 11-18-2003 07:14 AM

    Posting Rules  
    You may post new threads
    You may post replies
    You may not post attachments
    You may not edit your posts

    BB code is On
    Smilies are On
    [IMG] code is On
    HTML code is Off
    Trackbacks are On
    Pingbacks are On
    Refbacks are On

     

    Title goes here

    close
    video goes here
    description goes here. Read Full Story
    For the best viewing experience please update your browser to Google Chrome