Pagoda SL Group

W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: ekslee on August 09, 2011, 08:13:38

Title: No power at low RPM
Post by: ekslee on August 09, 2011, 08:13:38: 1969 280SL, automatic trans

Under 1,500 RPM - no power. Sounds fine revving in Neutral, but putting in gear and trying to get moving causes severe "chugging" (don't know how else to describe). Very difficult to get moving up a slight incline. Downshifting to "2" lessens the problem. It's easy to replicate the problem by pressing the gas and brake at the same time. Once car is moving and RPMs get up to 1,500, everything seems to be fine.

Recently blew the fuel pump fuse and replaced it. Don't think that would have anything to do with the current problem, but thought I'd mention it. Car runs fine at higher revs, I don't think there's anything wrong w/the pump, now.
Title: Re: No power at low RPM
Post by: ja17 on August 09, 2011, 12:42:41: Hello,

What is the history of the problem? Something recent? Did it come about all at once?
Title: Re: No power at low RPM
Post by: ekslee on August 10, 2011, 06:34:28: Sorry, not really sure. It's my Mom's car. She's been complaining about it chugging and sputtering, but she's not very good at describing the symptoms. After changing the fuel pump fuse (couple weeks ago), it seemed fine. I'm sure it was having the problem, but I just didn't experience it. It had some bad incidences on Mom's next drive, so she didn't drive it after that. Next drive was the drive where I figured out what the symptoms were.
Title: Re: No power at low RPM
Post by: J. Huber on August 10, 2011, 14:48:10: I'd check the dwell and condition of points and plugs first.
Title: Re: No power at low RPM
Post by: ekslee on August 11, 2011, 04:30:41: I'll do that. Points and plugs are pretty new, but I'll check the ignition stuff, and let you know. Wonder if it could be some timing/advance problem.
Title: Re: No power at low RPM
Post by: ja17 on August 11, 2011, 04:49:20: If the car has not been exercised and has just been moved about, started and stopped, the new plugs can be fouled.
Title: Re: No power at low RPM
Post by: ekslee on August 14, 2011, 03:19:51: Joe,
Good call. I checked the plugs (OK), distributor cap and rotor (cleaned the crud off the cap contacts), and cleaned the points. This made a significant difference. Problem was still there, but quite a bit improved.

Then I remembered, "Oh yeah, I need to check the dwell." It was waaay off - probably about 45 deg. My vague recollection was that 28 deg was about right, but the dwell get really spastic below 30 deg, so I settled for 30 deg. What a big difference! Guess the dwell has been increasing gradually over some time. Come to think of it, it has been a little harder starting, for a while.

Thanks for the help!
Title: Re: No power at low RPM
Post by: Benz Dr. on August 14, 2011, 20:12:57: It depends which distributor you have. If it's the aluminium one 30 degrees is perfect. If it's the cast iron version 38 - 40 would be what you need.