Author Topic: Car let me down - advice needed ! HELP !  (Read 6198 times)

Ben

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Car let me down - advice needed ! HELP !
« on: November 03, 2005, 05:49:43 »
My ’64 230SL let me down last night for the first time in 4 years and 50,000 miles. Not only that but it happened when I needed it most !

I ended up using this car for a trip into the city on a miserable wet evening as my father had the other car whilst my wife had our main car. I had to take a trip into the “dark side” of town to collect my 5 year old daughter who was appearing on stage in a musical. I was having trouble with a flat battery on the days previously and having checked the charging rate and found it to be low I charged the battery, tested it and replaced the fan belt which corrected the low charging rate. So far so good. I therefore decided it would be okay to drive and brought my booster pack AND a set of jump leads.

The car started and ran fine but after about 10 miles the idle dropped a bit and the car started to cut out every time I clutched to a stop. It didn’t cut out instantly but just idled for about 30 seconds and dies. It did this repeatedly whilst in heavy traffic. The ambient temperature was cold, about 8-10 deg C, and the operating temp was perfect at 180 F (don’t you love the two scales ). Anyway my battery / charging issue was obviously cured as I had plenty of cranking power each time, even using lights, wipers and radio. It took 3 attempts each time to restart but did so relatively quickly.

I parked up and collected my daughter and returned to the car, having left it sit for about 15 minutes. It would not start. It turned over quickly, repeatedly but wouldn’t fire. I gave it a cursory glance in case I had disturbed something earlier but found nothing. I checked for spark at the points and got it. I wondered if it was flooded , although I don’t recall smelling fuel, and removed both the fuel pump and CSV fuses and spun it over with a wide open throttle for a short time. Still nothing, not even a splutter.

At this time I felt the battery voltage was dropping so I hooked up the booster. Again it spun over with no trace of starting. I wondered about the coil being okay, then fuel starvation, though having reinserted the fuses I could hear the pump running. I wondered about vaporisation, though having never experienced it over the last 4 years even in summer traffic it seemed doubtful. So I figured the famous “push” switch in the cabin for the CSV could’ve helped. I ran a wire from the switch to the battery and had my 5 year old crank the engine, it did splutter and make an attempt to start. I repeated this a few times but seemed unable to “finesse” the CSV accurately.

 The booster grew weak and when a group of guys approached a nearby parked car I asked and they agreed to give me a push, at which point it started INSTANTLY with minimal effort and I drove all the way home. The car didn’t stall, or rather I didn’t allow it to, but it did misfire anytime I floored it. It was an irregular misfire, i.e not any specific cylinder, and it cleared upon reducing the throttle. It would still do 75MPH but flooring it caused little acceleration but a lot of stumbling. It started and drove perfectly this morning !

Any ideas ?

I have a few theories and want to start looking asap !   What do the experts say ?


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

hands_aus

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Re: Car let me down - advice needed ! HELP !
« Reply #1 on: November 03, 2005, 06:44:32 »
Hey Ben,
How old are the points?
You can get spark with worn points but if the points rubbing block is worn the dwell angle and timing goes out of spec.



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: Car let me down - advice needed ! HELP !
« Reply #2 on: November 03, 2005, 06:48:34 »
Hi Ben,

I had something similar happen to me.  Turned out to be a loose terminal connection on the battery.  I had been working on something and put the neg terminal back on and forgot to tighten it down.  

I'm trying to connect the dots with your battery charging and alternator belt replacement and not wander off into ignition systems etc.  Often my working in a related area is the cause of the problem.

Jeff C.
1970 280SL 4-speed

Ben

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Re: Car let me down - advice needed ! HELP !
« Reply #3 on: November 03, 2005, 07:01:20 »
Thanks Bob.......the points were put in about 6 months ago, so I dont think thats it. Besides it drove perfectly today !!

Jeff I checked ALL connections like that. Having thought long and hard about it all night I dont feel the two situations are related. I have had battery trouble for weeks, just didn't want to bite for a new battery as I felt it was alternator related. The cahrge is good now.

I wondered about the coil breaking down when heating up.The car did get hotter than normal for a while in traffic, but was colder on the motorway home with the missfire constant !

I feel its a fuel issue. Either vaporisation ( seems unlikely in this cold climate) or starvation. If it is starvation..........why now !

Unless having a poor battery voltage was reducing fuel volume ? Then the booster should've sorted that ! Poor coil voltage ? Again the booster should've sorted that too !

I'm gonna check/change the fuel filter anyway ....just for a look !

Best check the basics though, from start to finish. Earth straps, points, cap, rotor, HT leads, then a fuel volume test !

Anyone know how I can check my coil. I have a multimeter, what should I look for ???

Thanks for all/any help & suggestions !

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

Bob G ✝︎

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Re: Car let me down - advice needed ! HELP !
« Reply #4 on: November 03, 2005, 10:37:51 »
Ben:
two things come to mine. A bad coil and a cold start valve. Have you checked both?

Bob Geco

Ben

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Re: Car let me down - advice needed ! HELP !
« Reply #5 on: November 03, 2005, 10:47:38 »
Hi Bob, yeah the CSV check out okay !

I havent tested the coil yet, I was hoping someone could give me some specs............resistance or something ?

Thing is I've just driven it, almost the same distance into the City with no problems at all !!


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

German Dude

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Re: Car let me down - advice needed ! HELP !
« Reply #6 on: November 03, 2005, 11:07:20 »
I had a problem like this - also in inclement weather.
Turned out it was the alternator ground strap.

Good luck,

Juergen
64 230SL #2933, 4sp, signal red, white hard top
93 Citroen XM station wagon

Raymond

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Re: Car let me down - advice needed ! HELP !
« Reply #7 on: November 03, 2005, 18:02:36 »
Could be really simple.  You said the temp was 8-10 C. and it was raining.  Could you have had condensation inside the distributor cap? Or, how about water in the top of the coil.  You let the car sit for 15 min. and it wouldn't start.  Could it have been more condensation?
You say the car now runs fine in warm dry weather.  

You might look for hairline cracks in the top of the coil or the distributor cap.

Ray
'68 280SL 4-spd Coupe
Ray
'68 280SL 5-spd "California" Coupe

ja17

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Re: Car let me down - advice needed ! HELP !
« Reply #8 on: November 03, 2005, 19:57:21 »
Hello Ben,
Do you have the original coil in the car? There are some variations, however they should not show over 5.0 ohms  at 70 degrees F. on any of them.

The original coil should show 1.7 to 2.1 ohms at 70 deg. F.

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

Ben

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Re: Car let me down - advice needed ! HELP !
« Reply #9 on: November 04, 2005, 02:33:44 »
Many thanks Joe for the figures,it IS the original coil, certainly very old, so I will check it today and post what I get !

Ray, the cap and rotor are fairly new and were completely dry !

Juergen, good suggestion, I will check that and clean it up either way !

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

hands_aus

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Re: Car let me down - advice needed ! HELP !
« Reply #10 on: November 04, 2005, 06:10:28 »
A loose wire will cause a resistance and voltage will be reduced and the engine will die. You just need to find where this is happening.
Feel the connections for heat.

could it be a faulty ignition switch?

What about the earth wire 'inside' the distributor?

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

Ben

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Re: Car let me down - advice needed ! HELP !
« Reply #11 on: November 04, 2005, 09:21:55 »
Bob, the ignitions switch is a non standard, and extremely ugly contraption, it could be causing problems. I've no idea how old it is.

I overhauled the dizzie earlier this year so AFAIK the earth here is good, however its a good check...............then again I know I had a spark................ of sorts !!

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

A Dalton

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Re: Car let me down - advice needed ! HELP !
« Reply #12 on: November 04, 2005, 10:15:36 »
If one suspects an intermittent ignition power feed problem from the ign sw or assosciated wiring/circuit, here is a simple way to help isolte the problem.
 Run a wire from the Bat + terminal to a toggle sw. in the cabin.. other end gets hooked to the ballast resistor, ign  feed side..
 Now , when the problem/misfires start to happen, sw this toggle ON and see if it clears the problem.. If yes, ign sw/circuit is suspect.
 You can also try this on the other side of the ballast for a quick test of possible bad ballst resistor [ opening when heated]..
Intermittents have to occur to be found , so these in situ -temporary manual circuit jumpers sometimes help in diagnosis.............
 I would check fuel filter/flow first...
« Last Edit: November 04, 2005, 10:34:26 by A Dalton »

hands_aus

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Re: Car let me down - advice needed ! HELP !
« Reply #13 on: November 06, 2005, 06:03:55 »
What about a faulty capacitor?

Is it the original capacitor too?

I read in the Haynes manual (of all places) that a capacitor that is breaking down will be alright cold but symptoms start as the car warms up.

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

Ben

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Re: Car let me down - advice needed ! HELP !
« Reply #14 on: November 07, 2005, 03:24:34 »
Thats another good tip Arthur............I'll do it today !  BTW I hooked up the ballast bypass relay and it really makes a difference over here on these colder mornings. The car cracks to life after turning over for literally half the time it used to. It fires after about 2 seconds from cold !

I did this whilst checking around for other issues but found none. The car has driven and started perfectly ever since that night but I dont want to just leave it as it could happen anytime.I'll rig up that circuit and hope for the best.

If I get the chance I will check the fuel flow and change the filter this week.

Bob, the capacitor was changed about 6 months ago, but again due to the current trend for Bosch stuff to be of reduced quality it could be bad. Still I feel it would rare its head every time it got hot, but so far nothing !

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