1979 SL idle problem

[jr811]

1979 450SL when I first start my 450SL - it idles @1500RPM
after about 5 minutes it willdrop to 500-550 RPM
anyone else having this problem. Jim

[Richard Wooldridge]

Hi Jim,
What was the problem with your '79? Mine does the very same thing.

Thanks, RGW

[Bondavi]

Cold start slide solenoid sticking, check it and blast it with WD40. Test leads with 12V battery it should snap open/shut without ado.

[JBR]

Where is the cold start valve located, I have the same problem on my 73

[page62]

I had this problem when I first bought my car. I had to adjust the normal idle speed, which is too low. There's a white nylon screw (about 1/2" in diameter) sticking up just in front of the air cleaner assembly. With the engine hot, turn it to increase idle speed -- I'm pretty certain it's counterclockwise. Problem solved.

I would think the starting at 1500 rpm and slowly going down to regular idle is otherwise fine...but perhaps I'm misreading your post.