A Stuck Gas Pedal and Block Linkage Archeology

[baon3h]

I've inherited a 68' 280SL and have little knowledge about its past, unfortunately. The car runs ok after changing plugs, adjusting the linkage, an oil change and other fluids.

When adjusting the linkage I noticed that the push rod to the FIP was too short. That seemed odd but was easy to fix. Another issue I noticed is that the gas pedal would get stuck when the engine had been running for more than 15 minutes. I can get it free with my toe but that is obviously not safe.

I followed the linkages from the pedal to the block pivot, then up to the linkage rod and removed them all. The rod from block pivot to the intake manifold was completely bent. It had to be bent, because a straight rod would not clear the exhaust manifold for some reason. After measuring the rod length, I noticed that I had found my original FIP push rod. It has the correct dimensions, just horribly bent. Turns out, someone had swapped the two rods to make it "work".

I attached a couple of pictures. The first picture shows why my pedal gets stuck. The top of the pivot arm rubs against the exhaust manifold when the engine is warm and the manifold and pivot expand. You can see the shaved off tip of the pivot (yellow circle). The second picture is a wider shot of the overall pivot.

What is going on? Is the pivot arm in the wrong place?

[baon3h]

OK, so this shot from a different angle clearly shows that someone mounted the pivot upside down. From other close ups (https://www.sl113.org/forums/index.php?topic=28951.0) I can see that the long arm is supposed to connect to the manifold, and the short arm to the pedal linkage.

Now the question is, how do I remove the pivot and flip it around without removing the manifolds?

[baon3h]

I was able to get the retaining clip off after failing to loosen the nut behind the pivot arm. I had to remove the bushing to move it to the opposite side. Going to clean them now and then reassemble. I'm hopeful that this will fix all my issues.

I also noticed that my car has no heat shield. How important is it? Am I losing performance because the air in the intake is heated up?

[TJMart]

Baon3h,

Take a look at the link below that shows a small plastic "bearing bush" #23 that should be on the shaft bolt connected to the engine block. If that bushing is missing the linkage plate #27 will not rotate properly allowing all your linkage to move freely.

A small inexpensive part that has a huge impact on your linkage.

https://www.sls-hh-shop.de/de/mercedes-230-280sl-w113/30-gasgestaenge

Tony

[baon3h]

Hey Tony, you are spot on. That little bushing is indeed missing and explains the sloppy fit of the bearing.

[LindesayOne]

Hello baon.....For the last several days, I've been struggling with this pivot after removing it to fix a slight deformation. I needn't tell you about the difficulty in accessing the area with the manifolds in place. Actually, after spending a full day down there, I'm feeling quite competent; however, replacing the circlip has stumped me.
I had thought that the clip could be pushed into place with a flat screwdriver; however, with the tight quarters and lack of visibility, I was thwarted every time I tried.
Have you found a way of installing the clip?

John

[baon3h]

Hi John,

interesting, I had no issues with installing the clip. Maybe because my car has the plastic bushing missing? Try to remove the plastic bushing and just see if you can get the clip on without the pivot. That eliminates any issues with the groove.

[LindesayOne]

Well, I'm surprised! Seems that you've had no issues getting your hands into that confined, almost invisible space to install the clip. Perhaps your digital dexterity is better than mine.
The bushing is in place, and the groove is fully exposed. It was only a few days ago that I removed the clip, so if I can access it, there should be no problem with the reintallation. For now, I'm using an alligator clip to secure the pivot; far from ideal.
Anyway, you've given me reason to persevere.

John

[baon3h]

Hope it worked out! I ended up getting a few pivot arms laser cut from sendcutsend.com, added ball studs and pressed the brass bushing into the new arm. I have some extra if anyone is interested.

[LindesayOne]

Installation of the clip is on the back burner - perhaps until I remove the inlet manifold!
But thanks for introducing "sendcutsend". Looks like a great resource.

John