[StarFire_MK2]

In attempting to track down a suspected exhaust leak, I discovered the following. While holding my hand near the egr valve with the engine running, I could feel warm air pressure pulses coming from underneath the egr valve. I assume these are exhaust pulses. The valve itself is 3 years old, and I am getting no error codes.

Is this normal behaviour for the EGR valve?

 

[Bob Lincoln]

No, it isn't. The leak is dangerous, since CO gas is deadly, invisible and odorless. It's important to fix it right away.

It could be leaking at the recirculation tube, which goes from the exhaust manifold back to the intake manifold. It also could be leaking at the valve stem. Or you might have a cracked exhaust manifold. Whichever it is, don't put off a repair.

 

[StarFire_MK2]

Thanks

 

[ImperialCrown]

If there is a plastic EGR transducer valve and rubber hose, check for melted plastic. Excessive back-pressure possibly from a plugging cat can push exhaust out wherever it can.
The diverter valve is a one-way valve that pushes fresh air into the exhaust manifold to help oxidize unburned fuel before it reaches the cat. If this valve allows exhaust to travel the other way, it can burn up plastic/rubber parts and leak exhaust.
A working smog pump is necessary for this system to work properly. Excessive unburned fuel or rich mixtures can overwork and overheat a cat and cause the ceramic to meltdown and plug the exhaust exit. It can also be a fire hazard.

 

[B10alia]

It could also be something as simple as a leaky EGR valve gasket.

 

[StarFire_MK2]

Upon further examination, I've got a dime-sized hole in the exhaust manifold, very close to the EGR valve. Sigh. Looks like I'm gonna have to pull a manifold the next time I'm at the junkyard. Did the manifold change on the 2.2/2.5 n/a during the 87-94 production run?

 

[Bob Lincoln]

They should all be the same. Are you sure the hole is in the manifold, and not in the EGR tube? The manifold is a very thick casting.

 

[StarFire_MK2]

Not sure, no...I can't see very well in that part of the vehical (hole is on the underside) and don't know where the tube ends and manifold begins. I'll take a look tomorrow.