Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 10-31-2001, 11:58 AM
Registered User
 
Join Date: Apr 2001
Location: Washington, DC
Posts: 223
420SEL idle level

I recently drove my daughter's '88 420SEL and noticed that the idle went up to a steady 1,000 RPM when stopped in Park, but was steady at 600 RPM when stopped in Drive with the brake on (like at a stop light).

The car runs fine otherwise -- is the out-of-gear 1,000 RPM idle level anything to be concerned about?
Reply With Quote
  #2  
Old 10-31-2001, 04:06 PM
MIKE FREEMAN
Guest
 
Posts: n/a
THE IDLE IS SUPPOSED TO BE MODESTLY HIGHER IN NEUTRAL OR PARK. THE IDLE CONTROL IS CONNECTED TO THE NEUTRAL SAFTY SWITCH FOR THIS INPUT.
SINCE THIS CAR IS AN AUTOMATIC THE TACH. IS REALLY FOR ENTERTAINMENT,HAVE YOUR TACH. CHECKED AGAINST AN ELECTRONIC SHOP TACH. AND YOU WILL FIND THEY ARE OFF BY 100RPM OR MORE(TYPICAL)
MF
Reply With Quote
  #3  
Old 10-31-2001, 04:54 PM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
I have found that the idle control valve is usually at fault. Its expensive to replace.
__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k
Reply With Quote
  #4  
Old 11-02-2001, 11:18 AM
420benz's Avatar
Registered User
 
Join Date: Jul 2001
Posts: 961
Where is the idel control valve on the 420?
Reply With Quote
  #5  
Old 11-02-2001, 11:21 AM
Registered User
 
Join Date: Apr 2001
Location: Washington, DC
Posts: 223
In connection with replacement of the 420's radiator (hairline crack in top plastic), I had the idle control valve replaced -- was indeed expensive: $330 part [I let my idependent supply and charge list as I have frequently provided my own parts for other renewals] and $65 labor.

Has cured the idle irregularity.
Reply With Quote
  #6  
Old 11-02-2001, 11:23 AM
dpetryk's Avatar
Electrons can do anything
 
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
Its directly in front of the throttle body and behind the water pump on top of the engine.
__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k
Reply With Quote
  #7  
Old 11-02-2001, 01:27 PM
Registered User
 
Join Date: Oct 2001
Location: Boca Raton, FL
Posts: 12
I have experienced a similar problem with my '86 420 SEL but it usually occurs after a prolonged driving at highway speed. I was able to verify that it was indeed the idle control valve by giving it a tap of a wrench with the engine running...it then settled down to "normal" (around 600 RPM). My mechanic said that the bugger can be cleaned out...I wonder how that's done...sure would prefer that to spending $300+!!!
__________________
Ralph S. Robbins
Boca Raton, FL
'86 420SEL
163k (as of 10/01)
Reply With Quote
  #8  
Old 11-02-2001, 01:35 PM
Registered User
 
Join Date: Apr 2001
Location: Washington, DC
Posts: 223
Our high idle was persistent -- stable 600 RPM in gear stopped with brake on and steady 1100 RPM in park or neutral -- didn't seem related to any driving conditions.

My independent is very reliable and doesn't do additional work unless needed, so I assume that they checked the valve and found it needed replacement (I picked the car up after hours and haven't had the chance to discus it with them).

Our car was a low mileage (75,000 on an '88) grandparent's car which I'm going ahead and refurbishing all items as they come up since in addition to its being my 16-year old daughter's daily driver (high priority on reliability and safety), we use it for long distance family trips to keep the mileage down on our newer leased cars (like my C43 AMG) -- I'm willing to pay the price for certainty of reliability in such a solid, roomy cruiser -- they don't build 'em like the old 126s (tho I may trade up for a '98 or '99 140 in a couple of years).
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mercedes (and BMW) straight sixes have a rough idle "by design"?! sanchezc Tech Help 32 12-22-2014 07:01 PM
380SL Idle Problem Kevin_300CE Tech Help 4 08-02-2007 06:50 PM
'83 380 SL fast idle problem Dorbell Tech Help 3 08-23-2004 10:25 PM
1967 230s idle problem techrondon Vintage Mercedes 17 03-29-2004 11:25 AM
420SEL Idle Control Module William Tech Help 2 01-31-2002 09:31 AM



All times are GMT -4. The time now is 12:12 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page