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vacuum leak at EGR?; seems to leak a tad when tested
Topic Started: Jan 29 2013, 07:41 PM (711 Views)
rjsdotorg
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I was testing in general just now, and was concerned about an idle vacuum reading of 17" when warm - idle was ~900.
So, I sprayed around hoses and TB with ether. The only place I saw any effect was the diaphragm of the EGR near the center. It opens and closes and all, and when opened at all at idle it dies, so that's normal.
Does the EGR always leak a tad, or should it be air tight?

BTW, I took the air inlet diverter hose off of the EGR line and put it on the canister purge line.

I also then recalled I'm at 4000' and so normal vacuum is lower; according to this nice vacuum diagnosis link: http://www.gregsengine.com/using-a-vacuum-gauge.html it should be 15"-19".
Edited by rjsdotorg, Jan 29 2013, 10:07 PM.
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Waldo
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The EGR valves job is designed to "produce" a leak. It routes a small amount of the exhaust gas into the intake. However, it should not leak "outside" air into the intake. From what you describe, it sounds like the EGR diaphram may have a small leak. Someone may correct me if I'm wrong here, but that's my 2 cents.
:popcorn
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rjsdotorg
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I pulled the valve off at lunch - still reasonably clean.
I suspected the hole where the steel pin goes into the valve body from the diaphragm, so I put a dab of syn grease there and worked it in. If that leaks (there is no real seal) outside air will get in.
I re-did a worn hose at the diaphragm, and wiped some RTV over the diaphragm with a Q-tip. I then did a light pressure test (toy pump) under water - no bubbles.

I might also try the modulator bypass elsewhere suggested (mwebb?) and see how it runs for me.
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