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Old 04-07-2001, 10:37 PM
Registered User
Join Date: May 1999
Posts: 205
I had a "Chek engine " code that idicated EGR valve enoparable. I removed the valve. How do I test it?
So far all I did is blow/sucked some air through the
vacum port and noticed that the air was moving freely and
the membrane inside did not move.
90' 300CE
17" Intra Signums
Brulen mufler
Euro Headlights/Clear Blinkers
White gouges (made my own)
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Old 04-07-2001, 10:57 PM
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Join Date: Mar 2001
Posts: 326
A hand held vacuum tester is the most inexpensive and effective way to test. Available at most auto stores.
Scott Diener
89 300E
93 300E
92 Volvo 740 Wagon aka "Mutt mover"
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Old 04-08-2001, 09:00 AM
Posts: n/a
To give a little more detail to the last post, apply vacuum to the vacuum line on top of the valve. The typical failure I am told, is for the diaphragm to fail. If this is the case, you will not be able to draw a vac above the diaphragm.
My 91 300TE has this problem. The car runs fine without a functioning EGR and blew away the last emissions test, so it is low on my to do list. I saw new EGRs on Fastlane for about $140, a good bit below most others' prices.

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Old 04-08-2001, 09:01 AM
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Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 11,234
here you go

You need to put negative pressure on the vacuum port of the EGR valve and then try to blow into one of the other ports - if air comes out the other side then the EGR valve is working. If the valve is working then you want to check for pluggage in the EGR pipe from the valve to the intake manifold.

With the engine warm - at operating temp - put your vacuum pump on the vacuum port of the EGR valve and put some negative pressure on it. The engine should lower in idle speed and/or near about stall. If this does NOT happen then you need to "rod" out the EGR pipe from the EGR valve to the intake manifold. You will need a piece of old speedometer cable that is flexible all the way to the end. You may have to modify the speedo cable because most of them have a rigid end that will not make the 90 degree bend through the EGR pipe at the intake manifold (you do not need to ask me how I know this). Anyway, shove the speedo cable through the EGR pipe, hook a drill motor to it and spin it inside the pipe. I found that the last 1 to 2 inches of the pipe at the intake manifold was where the most severe pluggage was.

'85 300D, no check engine light here
'95 E320
'97 CRV
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Old 04-08-2001, 09:13 AM
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Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,768
An easy test for an operating EGR system with the
vac. pump is to pull vac on egr when car is at idle.
The valve should open and make the idle very rough. Release the vac and it shoud even out.
However, It should be noted that some engine are prone to a blockage at the intake pipe from the egr valve. This will
diagnose as a bad [ non-opening] egr. [104 engine is a common case in point. [see SB's article in DIYer section]
That can be diagnosed by opening line at egr [ pipe running from egr to intake], and feeling for vac with thumb at idle, No vac= plugged pipe.
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