How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Marty Your Own Question

Marty
Marty, Bosch Certified Master Technician
Category: Car
Satisfied Customers: 53783
Experience:  Bosch Certified Master Technician with over 35 years experience in the automotive industry.
13230946
Type Your Car Question Here...
Marty is online now

I have a 1989 Mercedes 300 SL ( 107 ) series I cannot start

Resolved Question:

I have a 1989 Mercedes 300 SL ( 107 ) series
I cannot start it in cold weather It will start no problem when warm In cold weather it will turn over no problem and when you release the key from the Turn engine position it will try to fire up but will not do so
Submitted: 1 year ago.
Category: Car
Expert:  Marty replied 1 year ago.
Hi, it sounds like you may have a bad overvoltage protection relay or a blown fuse in the relay. The relay is located on the relay panel above the fuse box. I'd also check the ignition system. Worn spark plugs, a bad cap and rotor or a weak coil or low voltage to the coil could also cause the problem. I'd start by checking the relay since it is essential for the cold starting. The fuel mixture should also be checked and adjusted as needed.Let me know if you have any questions.Please be sure to click on a rating for my service.Marty
Customer: replied 1 year ago.
Do you have any photo or sketch that would indicate this relay switch
Expert:  Marty replied 1 year ago.
It's located above the fuse box. I've attached a picture below. It' the relay with the red top.
Customer: replied 1 year ago.
Thank you for that
I have located the relay switch and the fuse in it is intact. Unless of course the relay itself is faulty
Taking off the distributor cover is a major operation as it is located at the front of the head and the radiator may need to come out first to get access to an Allen key bolt underneath at the base of the distributor
I am wondering if it is more a fuel issue as when you succed in getting it started you have to leave it just tick over at idle speed until it is completely warmed up as if you try and give it any throttle whatsoever it will just cut out
Expert:  Marty replied 1 year ago.
It could be fuel or ignition. You need more fuel when it's cold and you need hotter spark when it's cold. You might try replacing the relay and see if it helps. I'd also check the fuel mixture.
Customer: replied 1 year ago.
Last question. How do you check the fuelixture
Expert:  Marty replied 1 year ago.
To check it properly you need a gas analyzer or you need to connect an ammeter to the EHA valve on the side of the fuel distributor to measure the current draw. A simple way of testing the mixture is to remove the air cleaner and gently press down on the air flow sensor plate and see if the engine rpm increases. If it does it tells you that the mixture is too lean. Do this both cold and hot to see if the mixture is off. You don't need to press very far when doing the test. About 1 - 2 mm is enough.
Marty, Bosch Certified Master Technician
Category: Car
Satisfied Customers: 53783
Experience: Bosch Certified Master Technician with over 35 years experience in the automotive industry.
Marty and other Car Specialists are ready to help you

What Customers are Saying:

 
 
 
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
< Previous | Next >
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex
 
 
 

Meet The Experts:

 
 
 
  • Greg

    Greg

    Technician

    Satisfied Customers:

    1067
    Automotive diagnostic tech
< Previous | Next >
  • http://ww2.justanswer.co.uk/uploads/IN/indytech/2013-8-8_102717_SantoDomingo146598x6402.64x64.jpg Greg's Avatar

    Greg

    Technician

    Satisfied Customers:

    1067
    Automotive diagnostic tech
  • http://ww2.justanswer.co.uk/uploads/35/350matt/2012-6-7_182356_matsavatr.64x64.jpg Matt's Avatar

    Matt

    Mechanical Engineer

    Satisfied Customers:

    4197
    BEng hons Mech engineering, in auto industry 22 years
  • http://ww2.justanswer.co.uk/uploads/TE/techmachine/0601821347169_717372168_8940977_39623330_o.64x64.jpg Ross's Avatar

    Ross

    Diagnostic and repair technician

    Satisfied Customers:

    452
    Licensed diagnostic and repair technician
  • http://ww2.justanswer.co.uk/uploads/RO/RobMechanic/068.64x64.JPG Rob's Avatar

    Rob

    ASE Certified Technician

    Satisfied Customers:

    82
    30 years trade experience
  • http://ww2.justanswer.co.uk/uploads/UK/ukiaibal/2012-11-9_205920_SAM0109.64x64.JPG uk_iaibal's Avatar

    uk_iaibal

    UK Car Mechanic

    Satisfied Customers:

    1
    Verified Car Mechanic.
  • http://ww2.justanswer.co.uk/uploads/NA/nabilc/nabilc_avatar.64x64.jpg Billy's Avatar

    Billy

    Trainer/ Master Technician

    Satisfied Customers:

    38
    Trainer 8+ years, master tech. 10+ years, SAE member
  • http://ww2.justanswer.co.uk/uploads/MI/mikeamechanic/2013-4-2_175558_photo.64x64.JPG Mike Kelly's Avatar

    Mike Kelly

    Auto Service Technician

    Satisfied Customers:

    1256
    17 years experience as an auto mechanic, foreign and domestic. 5 years running my own repair business.