Pagoda SL Group
W113 Pagoda SL Group => General Discussion => Topic started by: AlanT on February 16, 2023, 05:04:17
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280SL Stumble Solved
This was a multi layered issue that on remediation has resulted in a beautiful powerful smooth running car.
The Car: 1969 280SL California Coupe 93,000 genuine miles. 576G/040
Tenure: Owned for 12 years, driven circa 200 miles per year. Full History.
The Problem: After 30 mins plus of driving an intermittent idling stumble which years later grew to stuttering on acceleration. This advanced to a failure of ignition at 4000 rpm and some weeks later, catastrophic backfiring and rough running without power to proceed.
The diagnosis:
This was a combination of ignition and fuel supply failure.
Part of the problem only occurred post heat transmission to engine peripherals, whilst the fuel delivery issue was constant.
The individual failures;
- 1k Resistor Lead Connectors had failed, particularly once heat had transferred to engine peripherals
- Radio Suppressor Capacitor had failed shorting to ground
- Distributor Capacitor had failed shorting to ground
- Woven Battery Earth Lead shorting on Ballast Resistor
- Rotor Button had failed and burnt
- Fuel Pump wire strainer filter end had dislodged and intermittently blocked fuel entry to pump body
The completed works:
- Tied back Woven Battery Earth Lead
- Checked Ballast power and resistance
- Checked Original Regulator with Beru Replacement (Beru later returned to inventory)
- Replaced Fuel Tank with genuine part
- Replaced Foam Tank Ring with genuine part
- Replaced Tank Filler Neck to Body Seal with Oldtimer Part
- Replaced internal boot Tank Filler Neck Cover Seal with non genuine foam sealant strip
- Replaced Fuel Tank Strainer with genuine part
- Replaced Fuel Hoses with genuine parts
- Replaced Rotor Button with Bosch genuine
- Replaced Leads and Resistor ends with Bremi Bakelite 1KOHM. Early 280SL requiring Bakelite.
- Replaced Spark Plugs with NGK5ES
- Replaced Distributor Capacitor with unit of equal value
- Replaced Radio Suppressor Capacitor with unit of equal value.
- Dismantled Fuel Pump, machined commutator, removed debris from pump body, reassembled
- Replaced Flat Head Body Fixing Bolts to fuel pump cover from Authentic Classics
- Dismantled Fuel Pressure Diaphragm and checked, reassembled.
- Removed, cleaned and tested Throttle Switch
- Removed, tested, reseated Cold Start Valve
- Cleaned and reassembled Fuel Filter
- Measured Dwell
- Inspected Points
- Inspected Distributor Body Insulation
- Inspected Distributor Shaft
Ignition/Fuel Works scheduled:
- Replace Fuel Injectors
- Replace Fuel Filter
- Replace Fuel Strainer to Bosch Short Pump (Originally Long Pump)
- Replace Distributor Cap
- Replace Ignition Switch
- Replace Battery with Bosch correct dimension
- Replace Battery Shelf Plate
- Replace Throttle Linkage Bushings and Ends
- Replace Injector Pump Gaskets (small oil leak)
- Check WRD
The learns:
- Check the basics first; leads, plugs, distributor, capacitors etc
- Refresh the fuel pump, very easy job
- Look further afield, i.e. ignition switch, regulator etc.
- Search for shorting to ground and current supply restrictions to both plugs and coil.
On this job, a big thanks to Mercedes Benz Classic Centre California, George at Authentic Classics, Patrick at Oldtimer and Kevin at McStar Australia.
Finally a heartfelt thanks to all the contributors on this forum. The knowledge base is exceptional and has helped me tremendously on my long Pagoda journey.
I hope members benefit from the above.
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Wow Allan,
What and extensive job. Well done, wishing you many, many happy miles ahead.
Regards
Chris
Cape Town
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Welcome Alan,
Not sure we have met but probably at one of the Pagoda meets or the MBCV SL runs.
Good to see you get it all fixed.
Garry
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Thanks Chris and Garry, much appreciated.
Garry, we have met many years ago, once by accident in Middle Park when you "Heard" me coming and yes at some subsequent Pagoda coffee catchups. Good to hear from you!
I'm going through this car from one end to the other with a "sympathetic" restoration purchasing original wherever possible and preserving the original patina as much as I can. I have thoroughly benefitted from this forum, the detail is incredible and the spirit even better!
I'm sure I'll see you again some time.........
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This sounds to be identical to my issues .
Issues when engine reaches operating temps can further complicate .
And as said, may times its a combination of things .