High idle / high rpms - Mercedes Forum - Mercedes Benz Enthusiast Forums

General Tech Post general Mercedes Tech questions here.

High idle / high rpms

Old 03-10-2008, 08:29 PM
Thread Starter
Join Date: Mar 2008
Posts: 1
Default High idle / high rpms

I bought my first mercedes this weekend and brought it home. A 1976 450 SLC. As I drove it home I found 3 obvious things that need attention. The first was that the odometer and cruise control didn't work.

The two things that concerned me was the high idle while in park (engine cold and warm) it idled between 1000 and 1500 with a rare drop to about 800.

The second thing that concerned me was that the rpm's were between 2600 and 2800 at 60 mph. I counted the gears from take off and there were 3 (should be right for this car based on what I've read in that 3 speed automatics were prior to 1980.

any ideas or suggestions that anyone has would be greatly appreciated.
Old 03-26-2008, 05:07 PM
Join Date: Mar 2008
Posts: 18
Default RE: High idle / high rpms

You've got an Air leak, to be blunt. If u can get some brake/clutch cleaner, spray a tiny amount around the engine. This causes the engine to raise the revs and should narrow your search. Also, look for split vacuum hoses etc
Related Topics
Thread Starter
Last Post
Mercedes CLK Class
04-13-2009 04:06 PM
Mercedes E Class
12-10-2008 02:59 AM
General Tech
12-09-2008 04:08 AM
84 500SL Euro
Mercedes SL Class
09-23-2008 12:00 PM
Mercedes SLK Class
01-19-2008 12:49 AM

Thread Tools
Search this Thread
Quick Reply: High idle / high rpms

Featured Sponsors
Vendor Directory

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.