SL/R107: 560SL, sat for 5 years, many problems, no experience...
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Newbie
Joined: Jul 2025
Posts: 1
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560SL, sat for 5 years, many problems, no experience...
Personal background: No car experience at all lol, I've just always drooled over MBs. However, I have one family member who is a life-long GM mechanic and another in the business of everything vehicle-related building/replacing/repairing/sourcing (but still mostly domestic).
Car background: I recently purchased a 1986 560SL. It had sat for 5 years. Prior to that the seller told me it ran great. The seller also told me that the radiator, alternator, cylinder head gasket, and tires were all replaced before sitting as well. Never had any transmission problems.
What I've done: Tried starting it, no whirr from the fuel pumps but would crank so the engine was not locked up. Replaced the battery, replaced both fuel pumps, replaced fuel filter. Took spark plugs out to (1) do a compression test ((absolutely stellar readings)) and (2) give the cylinders a nice long ATF bath. Spark plugs also replaced to OEM spec. After soaking and replacing, I heard the whirr of the fuel pumps but still would not crank over on its own. Also did an oil change in here. Moved to the fuel distributor, pulled the lines off the injectors and verified fuel was dripping from the lines. To my dismay, one line on each bank had no dribbles.
The distributor was then pulled against all advice I have read so far, but with a new one being $1,000+ I felt that I had no choice but to rebuild. After popping it open, two springs were completely stuck down and there was a ton of corrosion. I took my time, measured to the best of my ability, maintained a clean work area and used lots of compressed air and brake cleaner. I got it reassembled, got it back in the car. Started getting dribbles from each injector line. Pulled the injectors to make sure those were not junked up. Was getting spray from each injector, but very poor from injector 5. Less than a fine cone mist, but it was still something. I then tried to crank it over. It worked! I then let it run for about 30-45min.
It was then time to take it on its maiden voyage. Upon startup we could tell that there was a miss. It was idling beautifully around 900. I took it out. I have nothing to compare to but it definitely felt like I had to mash the gas pedal to get any sort of response from the engine. I also noticed that it did not want to shift. Again, I had to mash the gas pedal to get a downshift and it really held the RPMs for a while before an upshift. I got it back to the garage, shut it down, and started to work on determining which cylinder was missing. Also tore off the transmission pan, gasket, filter to do a fluid change.
I am pretty sure the miss is coming from cylinder 5, as when I pulled the spark plug again it was quite dirty and when trying to short it out nothing happened. Also the cylinder that was having poor fuel misting.
Another problem: I have to floor the gas pedal with each start up. Once it turns over it again, idles like a dream.
My problem: I got the car running (not well, but running). Where do I go from here? I don't like that I have to floor it to start it. I don't like the hesitation to shift. There are so many vacuum lines, modulators, actuators, valves, etc. Where should I begin? I understand that this car sat for 5 years, but I'm sure some of these problems are age-related exacerbated by poor maintenance prior to being sat. I am obviously coming at this from a zero-experience, learning as I go, reading forums & watching YouTube videos angle, and I am surrounded by people who can work on cars but are not experts in old foreigns. I just need some jumping points, topics to explore, any guidance at all.
I appreciate it!
Car background: I recently purchased a 1986 560SL. It had sat for 5 years. Prior to that the seller told me it ran great. The seller also told me that the radiator, alternator, cylinder head gasket, and tires were all replaced before sitting as well. Never had any transmission problems.
What I've done: Tried starting it, no whirr from the fuel pumps but would crank so the engine was not locked up. Replaced the battery, replaced both fuel pumps, replaced fuel filter. Took spark plugs out to (1) do a compression test ((absolutely stellar readings)) and (2) give the cylinders a nice long ATF bath. Spark plugs also replaced to OEM spec. After soaking and replacing, I heard the whirr of the fuel pumps but still would not crank over on its own. Also did an oil change in here. Moved to the fuel distributor, pulled the lines off the injectors and verified fuel was dripping from the lines. To my dismay, one line on each bank had no dribbles.
The distributor was then pulled against all advice I have read so far, but with a new one being $1,000+ I felt that I had no choice but to rebuild. After popping it open, two springs were completely stuck down and there was a ton of corrosion. I took my time, measured to the best of my ability, maintained a clean work area and used lots of compressed air and brake cleaner. I got it reassembled, got it back in the car. Started getting dribbles from each injector line. Pulled the injectors to make sure those were not junked up. Was getting spray from each injector, but very poor from injector 5. Less than a fine cone mist, but it was still something. I then tried to crank it over. It worked! I then let it run for about 30-45min.
It was then time to take it on its maiden voyage. Upon startup we could tell that there was a miss. It was idling beautifully around 900. I took it out. I have nothing to compare to but it definitely felt like I had to mash the gas pedal to get any sort of response from the engine. I also noticed that it did not want to shift. Again, I had to mash the gas pedal to get a downshift and it really held the RPMs for a while before an upshift. I got it back to the garage, shut it down, and started to work on determining which cylinder was missing. Also tore off the transmission pan, gasket, filter to do a fluid change.
I am pretty sure the miss is coming from cylinder 5, as when I pulled the spark plug again it was quite dirty and when trying to short it out nothing happened. Also the cylinder that was having poor fuel misting.
Another problem: I have to floor the gas pedal with each start up. Once it turns over it again, idles like a dream.
My problem: I got the car running (not well, but running). Where do I go from here? I don't like that I have to floor it to start it. I don't like the hesitation to shift. There are so many vacuum lines, modulators, actuators, valves, etc. Where should I begin? I understand that this car sat for 5 years, but I'm sure some of these problems are age-related exacerbated by poor maintenance prior to being sat. I am obviously coming at this from a zero-experience, learning as I go, reading forums & watching YouTube videos angle, and I am surrounded by people who can work on cars but are not experts in old foreigns. I just need some jumping points, topics to explore, any guidance at all.
I appreciate it!
Newbie
Joined: Dec 2007
Posts: 6
Likes: 1
380 sl
I bought an 89 560sl about a year ago that sat up for 12 years. Replaced the gas tank and both fuel pumps. Got it running and the trans was slipping badly. You are on the right track but keep driving the car. The more I drove mine the better everything got. I've got about 1000 miles on it since I got it running the transmission no longer slips, it idles well and has much more power than it did at first. Drive it and keep looking at the problems 1 at a time. Also they are slow off the line they start out in second gear. You can down shift to first and run up your rpms and then manually shift to second and then drive. It helped my trans slippage. Good luck and feel free to reach out. I'm no expert but I've done a lot of work on these cars.
