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-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 03-18-2002, 02:19 PM
Posts: n/a
EGR Valve function

Can anyone please explain to me the functioning of the EGR valve - I know it recirculates some of the exhaust gases back into the combustion chamber, but how does that reduce the combustion temperature (I believe that's what it does, so that the NOx emmissions are lower).

If one has to disconnect the EGR valve, what precautions should one take?

Reply With Quote
Old 03-18-2002, 03:06 PM
Registered User
Join Date: Dec 2001
Posts: 571
The EGR is part of the emission control system. Would disconnecting it trip a CHECK ENGINE light and/or cause the vehicle to fail an emissions test?
Reply With Quote
Old 03-18-2002, 05:49 PM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
EGR is used to introduce an inert gas to take up space so to speak. It quenches the flame and by doing so it can hold combustion temps to below the range where Nitrogen oxidizes.
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
Old 03-18-2002, 07:08 PM
Posts: n/a
So the inert gas would affect the performance of the car adversely, right (in terms of acceleration)? How about the fuel economy? What would happen if one disconnects it?

Reply With Quote
Old 03-19-2002, 11:01 AM
Posts: n/a
agupta: I have always believed - if the car was designed to use a part to run properly - don't redesign it - FIX THE PROBLEM. If the car runs better without the part - something is wrong - I firmly believe - two wrongs don't make a right. Just my opinion - Whether or not performance would be affected (Idon't know) - emissions will go higher.
Reply With Quote
Old 04-11-2002, 04:35 PM
surfblau's Avatar
neue Dieseler
Join Date: Feb 2002
Location: san francisco - immer kalt, immer windig, I want to move
Posts: 382
disconnecting EGR = risks?

Along the lines of the original post, I was wondering what the potential risks are with disconnecting the EGR (on my 84 TD).

I believe that the vacuum unit that controls the EGR valve on my car has a leak, and am wondering if it is worth replacing, or just plugging the input vacuum lines. I will study the emmissions schematic more before doing so, but it looks like there is only one line to the EGR valve, and this proceedure would disable the EGR.

I have seen other posts that describe using a bb to plug that line, but I was still wondering if there are any risks.

84 300TD - 235k - Farbe "Surfblau" bought at 213k
87 300SDL - 131k - Farbe "PimpGold" bought at 115k
00 Klepper Faltboot Expedition Double
Reply With Quote
Old 04-11-2002, 09:03 PM
Registered User
Join Date: Aug 2000
Posts: 49
On a diesel car, particularly the older 1980s types:

The "bb fix" only works if the rest of the vacuum system does not have leaks. If you are in a state where you are not inspected, you can get away with disconnecting the entire egr system, including the two "white valves" that are a part of it. Simply disconnect the two vacuum hoses as close to the main vacuum line (the larger diameter one) as you can. Plug the two locations at the rubber connector. The car will probably run better.

On a gasoline car:

If you are in a state that inspects (such as California) the emission control system, you will get busted, unless you re-connect the egr before the inspection. On more modern cars, that use numerous sensors and have a computer controlled system, you will be better off repairing any leaks and/or egr parts to get the car to operate properly.
Jeff Naumann
Torrance, California
1972 220D 138k miles (sold)
1982 300SD 263k miles
1989 BMW 750iL 183k miles
1993 Dodge D250 Cummins 5.9 202k Miles
Reply With Quote
Old 04-12-2002, 09:10 AM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
One of the reasons (many) not to disconnect EGR is the fact that engines ARE designed to run on this partially burnt fuel/air mixture. Disconnecting can cause engines to run HOTTER esp. on the DIESEL models!
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator
Reply With Quote


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
EGR blocked Jassper Diesel Discussion 32 02-12-2008 08:44 PM
Disabled EGR Valve. psdsteve Diesel Discussion 0 05-10-2004 01:36 AM
EGR (Exhaust Gas Ricirc.) Valve Test hifeverz Mercedes-Benz SL Discussion Forum 5 05-08-2004 10:02 PM
EGR valve non-functional jlauch Tech Help 3 01-21-2004 09:27 PM
no egr valve maximus Tech Help 9 04-09-2002 03:50 PM

All times are GMT -4. The time now is 09:17 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page