start problem when 280 sl is warm

[n/a]

My 230 sl (with a 280 sl engine) won't start too good when it's warm. The cold start is no problem. I have to be honest I haven't used the car for a long time (due to building a house) and it started up fine after not running for 6 months, but when hot its not starting as it should and takes too long for my liking...  I already had the pump thermostat replaced and it still hasn't solved the issue...

any tips or suggestions are welcome.

thanks,
Mark
De Woude
Netherlands

230 sl 2.8 - 1966

[JPMOSE]

If your 280 engine has a Starting solenoid on the back of the injector pump (late 280SL injector pump doesn't have one), make sure it operates.  This solenoid moves the rack into a rich position, which aids in starting.  Mine wasn't working until recently due to the relay requiring cleaning.  I noticed an improvement immediately when starting the car warm (or at full operating temperature).

If you are unfamiliar with testing the Starting solenoid, ask and more details will be provided.  This, of course, is only one possible cause of many!  Good luck.

Best Regards,

J. P. Mose
1968 250SL

[n/a]

thanks will check this over the weekend.

Mark

230 sl 2.8 - 1966

[Cees Klumper]

When I want to start my car with a warm engine here's my procedure:

1 - if it's been less than, say, 10 minutes since the engine ran, it will start right up
2 - if it's been longer, I turn on the ignition (fuel pump starts to whirr) but wait for about 7 seconds before trying to start it; it will then start up. If I try to start it straight away, it will take the same 7 seconds of cranking before it will go. So it seems that those 7 seconds are necessary for the fuel pressure to build back up. I suppose my check valves in the FI pump don't keep the pressure up for very long after the engine has been turned off; at least this is all I can think of that would explain these symptoms.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[hauser]

Have you tried to start it with the accelerator pedal fully depressed?  I find it helpfull when trying to star a warm engine.

1969 280sl 5 spd
Gainesville, Fl.

[Jonny B]

Mine is a combination with Cees and Hauser. If the car has not set for very long ~5 minute range, it will fire right off. If much longer than that, I will usually let the fuel pump run for a small bit, and then put the accelerator pedal to the floor, the car will usually pop right off.

Jonny B
1967 250SL Auto

[JPMOSE]

Yesterday, at the Blue Angels Air Show in Marietta, Georgia, I met another Pagoda owner with a '70 280SL.  He has owned it for 30+ years (never heard of this website...he does now).  He was discussing how hot summer weather caused hard restarting....he further discussed that the cooling system mod. (I believe Millers Mercedes offers this setup) cured the problem.  I thought it would be worth mentioning.  Perhaps someone else can validate this further.

Best Regards,

J. P. Mose
1968 250SL

[Ian45]

Hi J.P.

I would appreciate info on how to test the starter solenoid please.

Ian
1967 250SL
Derby,England

[JPMOSE]

Ian...look at the following thread on the Starting Solenoid:

http://index.php?topic=4859

If you still have questions after this, write back.  I will say that this solenoid simply engages everytime the ignition switch is turned to the "starting" position.  There is a relay associated with this operation on the left side of the engine compartment on the fender wall (back near the firewall).  If the relay doesn't function, neither will the starting solenoid.....so you need to check both.  In my case, I simply cleaned the contacts on the relay points (must disassemble the relay) If should be noted that a 1967 250SL, with it's original injector pump, has two wires connected to it.

Best Regards,

J. P. Mose
1968 250SL

[n/a]

Fantastic feedback, I will check all option, but believe it or not, now my battery went dead, probably because I havent used it a lot (which will change this summer!)

thanks again for all your responses!

PS. finally spring has arrived in Holland!!

230 sl 2.8 - 1966
ex 400 SEL 1993
ex 450 SEL 1974
ex 230.6 1966
ex 230.6 1974
ex 280S 1969

[n/a]

Guys the battery is replaced, i checked the wires to the solenoid on my fuelpump, and give a few seconds more to pump fuel to it before starting my car, and she fires up like nothing to it!

It's also helping because I am now driving it as my daily car, so it's getting used as it should be!

Thanks again to all contibutors to my question, happy cruising!

Mark

230 sl 2.8 - 1966
ex 400 SEL 1993
ex 450 SEL 1974
ex 230.6 1966
ex 230.6 1974
ex 280S 1969

[ted280sl]

Mark,
  The 230Sl model had the same coil that came out of the 190SL's. It is a weaker coil designed or a smaller engine. A relatively inexpensive upgrade to many of our cars is to change to the hotter red coil. This wil also requie that the ballast be changed. I did this a few years ago and have been very satisfied with the results.
Regards,
Ted 280SL w/ red coil