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How to check EGR Valve?

T

t78

Guest
Took the EGR off last night because I noticed that the valve was frozen (Hopefully this is my idle problem... trying everything....)

I was able to free it up some with WD40 and some other penetrating fluid. How would I check this thing to see if it still works? (before I put it back on) Should the valve stay up if I push it in and hold my finger over the vacuum hose connector and then let go of the valve?

Also, would it benefit to just block this thing off?

Thanks,

t78
 

Camtwister

Member
Joined
Sep 5, 2001
Messages
17
Location
Clovis, CA
Corvette
1971 Onterio Orange BB Covert
If your EGR valve was stuck in the open position it will certainly make your car idle rough. If you have a hand vacuum pump, apply vaccum to the valve and verify that it opens, and that it does not leak down. I do not know if it will stay open by blocking off the vacuum tube after manual opening. Your local smog laws may prevent you from leaving it off.
 
Joined
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Messages
2,231
Location
Northern Virginia
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71 Conv. (Sold) / 98 Pewter Coupe (Sold)
The WD40 is a good start. Just because it's freed up doesn't mean it's clean and will probably get all carbon gummed up again. You should use a wire brush to get it free of all carbon buildup and spotless where it meets the manifold but be careful, many of the original EGRs are no longer produced and as a result have become expensive and very hard to find. If the vacuum test that camtwister mentioned works, you should be good to go and not need to even mess with trying to block it off. If the vacuum test fails, head out to your nearest junkyard cause those things are high dollar if you want original.
 
1

1976C3

Guest
Push it in, if it is stuck or requires alot of force to move replace it.

I replaced mine cause it was stuck and when I tested it by pushing it open it has a little resistance which is correct (spring loaded resistance).

Once I put it on and hooked up the hoses, I removed the air cleaner and watched the rod in the EGR diaphram while I goosed the throttle linkage.

It was clearly moving as throttle increased. It does affect idle drasticly when its on vs off. I live in a emissions area so a properly working EGR is required. Keeping the egr working properly if installed is as important as having coolant, oil, good plugs etc to the performance of the car. If it has to be on it needs to be working properly.

You could always install it and plug the hoses from the intake valve to the cab & egr and remove the hose plugs for emission inspections. All it requires is setting the curb idle to run it this way.


The following places can get you a egr valve:http://www.smogfree.com/
http://www.americanauto.com/view/auto/parts/Chevy/Corvette

Good Luck
 
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Messages
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Location
Northern Virginia
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71 Conv. (Sold) / 98 Pewter Coupe (Sold)
T

t78

Guest
Perfect - I know what to look for now

Thanks for the quick replies guys.

I have been having the hardest time trying to get my engine to run under 1300 RPM by itself. I have replaced and tuned almost everything except for the EGR. I saw in my Haynes that a broken/stuck EGR would cause stalling, so I went ahead and checked it last night, and it was stuck in the up position.

I have gotten it to move freely using my fingers, and I can hear the sucking sound when I do it (while it's off the car). But if I put my finger over the vacuum hose connecter and push it up, there is no change in resistance. -Is this a bad sign, or do I need to have it on the engine for a better test?

Thanks so much for your help ! I've had this thing for over 2 months, and have only been able to drive it once because of this idle problem :( I'm dyin' to drive :) :D :cool

-T78
 
1

1976C3

Guest
hmm

This is what I would try myself. Place the egr system back together on the car (what 5 mins tops time) ensure all your hoses are free flowing and get some tape. Yup tape any kind will do you only need a little strip or this.

Tear off a little piece of tape and place it near the middle of the egr dvalve rod (rod piece in the middle that is exposed).

Cut your engine on and move out to the throttle linkage. Goose the throttle while watching the tape.

It should rise as the rpm's rise and lower as rpm lowers. If it does this then it is probablly functioning good enuff for government work.

I had to adjust the fast idle screw once I got my egr working properly. I had a couple of rough idles also and switched the egr hoses around some and found:

1. Ran best when the hoses ran from the intake fitting (piece with 2 ends, dont know name of it) like such.

1. front vaccum fitting on carb to top of intake air fitting.
2. EGR diaphram hose to lower intake fitting.

*shrug* I do not know if this how it should be, but once I did that and adjusted carb idle I see a big improvement in idle at 700rpm. It is not as erratic and will idle with AC on now rather than die like b4.

If the egr moves like it should then its usually just a matter of tweeking the fast idle screw.
 

Tom Bryant

Well-known member
Administrator
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Nov 9, 2000
Messages
7,197
Location
Edgerton, Ohio, United States
Corvette
1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
This may be Bubba talking but..............

if you don't have emissions inspections here is what I did to one. It was sticking open and causing rough idle. I forced it completely closed and the idle smoothed out. I then inserted a small, tight fitting ball bearing in the vacuum hose so it wouldn't be tempted to open again. Problem solved/ no visual modifications. Never acted up again.

Tom
 
Joined
Jun 5, 2001
Messages
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Re: This may be Bubba talking but..............

59Tom said:
This may be Bubba talking but..............
Stop it Tom, your killing me:L

Eric
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
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1969 Killer Shark
EGR

In the past, I have replaced EGR valves with the cheap aftermarket ones. One way to know this is if it comes with a washer kit with different sized center holes for different applications. In other words, a one size fits all with different washers.

I have not had good luck with these long term.

In the end, I find getting the OEM equipment is a huge plus.
 
T

t78

Guest
IT Worked !!!!!

It worked. After cleaning/freeing up the EGR, my L82 runs like a charm :) :D I couldn't believe it. After two months of troubleshooting, (and replacing lots of other parts), my problem was the EGR sticking open. It will now idle in gear with no problems.

I even checked it to make sure. I started it up, then pulled the EGR open with my fingers, and the engine started to cough/stall - once I let it close, it ran right back up.

I finally got to drive it down the street and back ! What a rush :) Now I know that all of the small headaches were worth it.
I've really got VetteFever now:)

Thank you guys for all of your help! :) :D :cool
 
Joined
Jun 5, 2001
Messages
2,231
Location
Northern Virginia
Corvette
71 Conv. (Sold) / 98 Pewter Coupe (Sold)
Re: IT Worked !!!!!

t78 said:
Yeaaaah!!!...I finally got to drive it down the street and back ! What a rush :) Now I know that all of the small headaches were worth it. I've really got VetteFever now:)

Congrats! Watch out Florida, here he comes!
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
T78,

Excellent. Now maybe you can drive it on over. I would love to see the car and maybe talk you into doing some wet sanding for me.

:)
 

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