Author Topic: Starting problems  (Read 8700 times)

n/a

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Starting problems
« on: November 11, 2005, 17:24:36 »
I have recently imported a 1967 280 SL Pagoda (automatic & fuel injection)from the US (I'm living in Holland) The car is in mint condition and very orginal. Because it had 95.000 miles on it and had not been used regularly I have decided to check and overhaul all moving parts e.g. engine, ignition, cylinder head suspension, brakes etc. It's surpising how parts can look like new but are faulty anyway. The work has been done by one of the few SL specialists that we have here in Holland. We are lucky to have a steady supply of orginal parts here in Holland. The car drives very well now but there is however one problem that we have not been able to fix and that is the poor starting of the engine after it has been switched off for approx. an hour. A completely cold engine start is so so. A warm start is perfect. The ignition has been completely replaced and the distributer has been overhauled by a specialist. The vacuum timing advance unit works fine. The injectors have been replaced and we have re checked dwell angle, timing CO% etc. The engine is in very good condition and the cylinder head has been completely overhauled. The warm running device on the injection pump works well. It's even more frustrating to read on all these forums that most people have no problems with the starting behaviour of their SL. Is there someone out here who had the same problems and nows where to look?

Cees Klumper

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Re: Starting problems
« Reply #1 on: November 11, 2005, 17:42:08 »
Welcome to the forums Alexander.

The difficult starting issue has been discussed here many times. I suggest you do a search on this topic.

You can also check the archives here for more relevant information:

http://www.sl113.org/articles/default.asp

Prettig weekend,

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic
« Last Edit: November 11, 2005, 17:42:40 by cees klumper »
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

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Re: Starting problems
« Reply #2 on: November 11, 2005, 18:34:33 »
Hi there Cees,

I did check the forum on exactly this problem and read a lot of interesting experiences. However I have not found an answer yet.
Thanks for your warm welcome message.

Alexander Mossel

quote:
Originally posted by cees klumper

Welcome to the forums Alexander.

The difficult starting issue has been discussed here many times. I suggest you do a search on this topic.

You can also check the archives here for more relevant information:

http://www.sl113.org/articles/default.asp

Prettig weekend,

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


Naj ✝︎

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Re: Starting problems
« Reply #3 on: November 12, 2005, 04:40:10 »
Alexander,
On my 280SL the most significant change came from changing to the later high HP starter (faster cranking speed) and bypassing the ballast resistor while cranking. There is an extra terminal on the new starter solenoid which facilitates the bypass.

naj

65 230SL
68 280SL
« Last Edit: November 12, 2005, 04:40:47 by naj »
68 280SL

hands_aus

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Re: Starting problems
« Reply #4 on: November 12, 2005, 06:08:00 »
One of the simple things to do is to allow the fuel pump to prime the system for about 10-20 seconds before trying to start the warm engine.

Also with a  hot engine it is 'ok' to push the accelerator pedal but not recommended with a cold engine.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
best of the best

jeffc280sl

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Re: Starting problems
« Reply #5 on: November 12, 2005, 06:23:17 »
Hello and welcome Alexander,

I must admit to having a similar start problem after 1 hour running  with my 1970 280SL.

Some have suggested our problem may be caused by the off hot engine vaporizing fuel in the fuel injector lines feeding the engine thus removing fuel available for restart after 1 hour.  I seem to recall someone saying later fuel injectors were updated somehow to compensate for this issue.  Many have installed a manual CSV switch in the cabin so that you can manually enrich the fuel mixture on startup.  Others suggest letting the fuel pump run for a few seconds by turning the key to the on position before finally moving the  start position.  Right now it's something I live with while tending to other projects like rust.  Maybe my comments will add to the discussion and we can get to the bottom of the issue.  You can search posts from the "experts" like Ja17, Benz Dr anhd A Dalton.  These three are the best in my opinion.

For your so so cold start (CSV) problem I'd look at the starter mod and the cold start valve system.  There are many posts on both subjects.  I have one on the CSV relay which was intermittant on my car and once fixed cold starts are great.

Jeff C.
1970 280SL 4-speed

n/a

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Re: Starting problems
« Reply #6 on: November 12, 2005, 09:03:46 »
Alexander,
On my 280SL the most significant change came from changing to the later high HP starter (faster cranking speed) and bypassing the ballast resistor while cranking. There is an extra terminal on the new starter solenoid which facilitates the bypass.

naj

65 230SL
68 280SL

Thank you for the suggestions. I have already done exactly what you suggest. My new 1.5HP starter runs so quickly that I'm almost tempted to let it drive the car instead of the engine! My car already came with a bypass relais for the ballast resistor. I'll keep you posted!

A Dalton

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Re: Starting problems
« Reply #7 on: November 12, 2005, 11:17:02 »
Testing:
  First, as mentioned .. turn key to Run and let the fuel pump run 20 secs or so .. this will ensure a fuel flow loop back to the tank and any vapor condition in the pre-FI pump lines/filter will be eliminated. Fuel filter assem grabs engine heat through mount. Retry starting before next test.
  Next, when condition exist, have someone crank the engine in Start position. While they do this , jumper 12v from the battery pos terminal to the single terminal on the CSV. for about 1 sec. If this immediately starts the engine , then you can eliminate this vapor condition [ usually in the injection lines, after the FI pump] with a Benz 1 sec relay modification kit [ I can give you that part # , if needed].. this was another common problem and this kit did remedy it .
Post results of these test to aid in further diagnosis...

 

« Last Edit: November 12, 2005, 11:46:36 by A Dalton »

ja17

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Re: Starting problems
« Reply #8 on: November 16, 2005, 21:39:28 »

Hello mossel,
Your W113 should have a starting solenoid on the injection pump also. If your injection pump has two solenoids, the top one is the starting solenoid. This solenoid should activate whenever the starter is activated. This rich-ens the fuel mixture during all starts. Hot wire the solenoid to make sure it is functional first.

Next test it with a test lamp to see if it is being energized during starting. It is activated by a relay which also can be bad. The relay is in the engine compartment and near to the left fender. It should be the first relay from the front.

Make sure the relay is getting power when the starter is engaged. The starter switch activates the coil in the relay.
The power to activate the starting solenoid comes through #6 fuse I believe ( check all your fuses), and through the relay to the starting solenoid.

Joe Alexander
Blacklick, Ohio
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

jcjblo

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Re: Starting problems
« Reply #9 on: November 17, 2005, 07:17:28 »
Could you please provide the part # of the relay modification kit.
Thanks in advance
quote:
Originally posted by A Dalton

Testing:
  First, as mentioned .. turn key to Run and let the fuel pump run 20 secs or so .. this will ensure a fuel flow loop back to the tank and any vapor condition in the pre-FI pump lines/filter will be eliminated. Fuel filter assem grabs engine heat through mount. Retry starting before next test.
  Next, when condition exist, have someone crank the engine in Start position. While they do this , jumper 12v from the battery pos terminal to the single terminal on the CSV. for about 1 sec. If this immediately starts the engine , then you can eliminate this vapor condition [ usually in the injection lines, after the FI pump] with a Benz 1 sec relay modification kit [ I can give you that part # , if needed].. this was another common problem and this kit did remedy it .
Post results of these test to aid in further diagnosis...

 





1965-230SL 4-speed Euro/Canada version, white (050) black leather interior

A Dalton

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Re: Starting problems
« Reply #10 on: November 17, 2005, 09:36:57 »
<< Could you please provide the part # of the relay modification kit.
Thanks in advance>>

I notice you have an .042.  That version has the 1 sec delay relay.  The mod kit is for later versions that did not have it.
 FYI , the kit is part #001 545 16 24 relay and 108 540 10 09 harness.

ted280sl

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Re: Starting problems
« Reply #11 on: November 17, 2005, 15:46:16 »
Alexander,
  No one has mentioned an easy upgrade for this problem. The '67 Pagodas have a weaker solenoid. I understand that the solenoid was used with the 190SL. It was recommended to me several years ago that I should upgrade to the red solenoid. When doing this the ballast needs to be changed as well. The results were significant and the costs were reasonable. I strongly suggest this upgrade.
Regards,
Ted 1969 280SL w/ red solenoid
Ted

A Dalton

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Re: Starting problems
« Reply #12 on: November 17, 2005, 16:02:42 »
Think you may  have your solinoid and ignition coil mixed up...


n/a

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Re: Starting problems
« Reply #13 on: November 17, 2005, 16:07:45 »
Ted,

Thank you for your reply. It puzzled me a bit because as far as I know there are only two solenoids that are involved here, both attached to the FI pump. One is the fuel cut off solenoid, which can be detached without any problems. The second one is the cold start solenoid.

q1: Do you mean that there is a stronger cold start solenoid for the FI pump?
q2: You mention a ballast (resistor). Are you not mixing it up with the ignition coil?

67 280SL

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Re: Starting problems
« Reply #14 on: November 17, 2005, 16:13:18 »
Guys,

The 1 sec modification kit was mainly used on the 230/250 SL. Mercedes has disontinued this kit because it didn't work so well after all, and as far as I know, it was never put into a 280 SL leaving the factory. I will however diagnose and try the suggestions and keep you posted.

67 280SL

n/a

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Re: Starting problems
« Reply #15 on: November 17, 2005, 16:24:02 »
Thank you A Dalton.

I still have one question. Has the Pressure regulating valve on my SL the same function as the pressure accumulator on later Bosch K-Jetronic systems? According to my Bosch manual the function of that part is:

1: to prevent pressure decrease in the system after the engine had been switched off (and thus preventing bad warm start behaviour)
2: to muffle any noise caused by the electric fuel pump.

If that is the case then replacing the pressure regulating valve could improve the half-warm start of my car don't you think?

67 280SL

bjudd

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Re: Starting problems
« Reply #16 on: November 17, 2005, 17:01:11 »
Originally posted by A Dalton


  First, as mentioned .. turn key to Run and let the fuel pump run 20 secs or so .. this will ensure a fuel flow loop back to the tank and .../quote]


After a major tune up my car was still taking a while to turn over.  I now turn the key on to start the fuel pump and buckle up then turn it over and she fires immediately.    Thanks!


bjudd
1969 280 SL 5 sp

A Dalton

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Re: Starting problems
« Reply #17 on: November 17, 2005, 17:33:45 »
If you go back to my first post , you will see we are trying to establish if the problem is before or after your FI pump. That is the purpose of the test and sequence.
 The damper and pre FI pump fuel flow system can easily be checked by doing the recommended 20 sec electric pump run test and post the results ..
 If that has no effect , we move to the second test..you can jumper to the CSV as recommnended and post those results .. that will tell if we have leaking ball valves or vapor lock problem after the pump.
 Your assumption that the later models did not use the modification 1 sec delay kit is not correct .. that is exactly the ones that the kit was made for .. they did not leave the factory with the kit b/c the kit was after all 113 production end and was a factory remedy for hot start vapor problems after short stops.  The 230 came from the factory with a 1 sec relay, but its purpose was not a vapor lock remedy .  It was starting aid. The 250 never had a 1 sec relay, as they used a hight temp CVS time thermo switch with a seperate rack relay that was not temp dependent .. that was eliminated when the R18Y pump changed the cone check valves in the pump to ball valves, as it was determined that this feature was no longer needed .. but , that is when the start problems came and that is why the kit came out .
 Many guys favor a cabin manual sw over the 1 sec delay kit, as there is better control.  The problem was aso helped with the later style pump, but there was still vapor problems , regardless , and mostly due to fuel filter hard mount to engine.
 Do those 2 test and see if there are any results... this will help in determining your problem.

Ben

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Re: Starting problems
« Reply #18 on: November 18, 2005, 03:19:07 »
quote:
The problem was aso helped with the later style pump, but there was still vapor problems , regardless , and mostly due to fuel filter hard mount to engine.



..........Arthur, has anyone ever considered insulating the fuel filter from the mount, maybe with a plate of some sort ?

Regards,
Ben in Ireland.
'64 230SL 4sp.

A Dalton

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Re: Starting problems
« Reply #19 on: November 18, 2005, 08:30:08 »
B

 Yes , they do it with an insulated block..

n/a

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Re: Starting problems
« Reply #20 on: December 07, 2005, 14:57:08 »
Ok people,

My diagnosis on this topic so far:

Cylinder head: complete overhaul
Compression: almost like new
Ignition: completele overhaul, timing perfect
CSV: sprays perfectly
Cold running device: complete overhaul
Fuel pump: pressure more than adequate, fuel lines perfect


67 280SL