EGR should hold vacuum right?

[bfroe]

Sorry if this is a silly question...

PO put a new EGR just before I bought the truck so it is still very new.

While replacing all the vac lines, I sucked on the one connected to the EGR, and it wouldn't hold any vacuum. I could almost breath through the hose !

Is this normal? I feel like it's yet another vacuum leak...

Thanks!
Ben

[FallonJeeper]

Sounds like the EGR or vacuum line is bad.

[Tripwire]

yes and no - IIRC

the only way to test it is while on the engine and hooded up to a engine vac source as a mityvac cant pull enough suction and the valve requires some exhaust back pressure to function

be sure its clean and the passeges are clear, bolt it back in with the gasket and run a temp line directly to a ported vac source, rev the engine and you should be able to feel the diaphram move with engine rpms

i learned this the hard way and spent 65 for a replacement egr i did not need

at idle manualy depress the diaphram with your fingers and the engine should start to die

[bfroe]

yes and no - IIRC

the only way to test it is while on the engine and hooded up to a engine vac source as a mityvac cant pull enough suction and the valve requires some exhaust back pressure to function

be sure its clean and the passeges are clear, bolt it back in with the gasket and run a temp line directly to a ported vac source, rev the engine and you should be able to feel the diaphram move with engine rpms

i learned this the hard way and spent 65 for a replacement egr i did not need

at idle manualy depress the diaphram with your fingers and the engine should start to die

Will do. soon as i put all the new vac lines in, thanks!

[Chevelleguy]

It is not that a hand held vacuum pump can't make enough vacuum to open the egr valve, it is that there has to be exhaust pressure to make the internal valving operate correctly. So in order to test the valve, you have to have it on a running engine.

There are two types of valves, positive and negative. Positive valves operate this way. Negative valves can be tested with a vacuum pump and don't need to be on a running engine.

[Tripwire]

thank god i was half right theres hope for me yet ! i thought it had something to do with back pressure but was not sure

thanks for a little more enlightenment

[smogdredd]

Aftermarket egr warning

Almost all aftermarket EGR valves flow too much causing a misfire at 2500 RPM under no load. This can be a problem in some states because of the way the high speed portion of the smog test is done. Always use the smallest restrictor in the package. Try to cross the OEM part number to a new Delco unit if posssible. If Youre vehicle fails due to a high HC reading at 2500 rpm this is often the cause. Unfortunatly the part suppliers are completly un-regulated and don't have to answer to anyone. Even in California.

[smogdredd]

Loaded mode?

Sorry if this is a silly question...

PO put a new EGR just before I bought the truck so it is still very new.

While replacing all the vac lines, I sucked on the one connected to the EGR, and it wouldn't hold any vacuum. I could almost breath through the hose !

Is this normal? I feel like it's yet another vacuum leak...

Thanks!
Ben

I've never done a loaded mode test on a vehicle wiyh an aftermarket EGR, The problem I metioned may not be an issue under load but if You live in a basic area it's often a problem.