EGR tube has a plastic ball in it - Why?
 

I have a 1989 Chevrolet K2500, 5.7L, TH400 AT, 8600 GVW pickup. The EGR tube running from the EGR valve to the EGR solenoid was just replaced due to a vacuum leak. I was able to find a NOS (GM 14102066) replacement tube.

It was discovered that the old tube had a plastic ball inserted in the soft rubber connector at the EGR valve end of the tube. One cannot blow air through the tube with this ball installed. I decided to insert the plastic ball in the replacement tube. I started the truck and after a couple of sputters the engine ran very smoothly. Good fix?!

What is the purpose of this small plastic ball? Essentially, it blocked off the tube. Thanks for your time and interest.

Back in the day, such a thing was done so that he EGR valve didn't work. I cant think of any vehicle that came stock with a plastic ball in the EGR tube. What would be the use besides making the EGR inoperable?

Thanks for the reply oilcanhenry!

I might have come up with a viable reason as to why the plastic ball was installed at the factory after performing a little bit more research. You are correct in that the installed plastic ball made inoperable or "deleted" the EGR system. A couple of things seem to indicate that this was definitely intentional.

1) Remember, the K2500 truck has a 350cid engine, 3-speed automatic transmission, and the one-ton chassis (8600 GVW - C6P option). The truck is/was considered a "heavy-duty, 3/4-ton" truck. In addition, the truck is also equipped with the towing package. It is my understanding that people opt to install an "EGR delete kit" that removes the EGR system thereby allowing the vehicle's engine to run at cooler temperatures. The installation of the small plastic ball into the EGR vacuum tube basically makes up an "EGR delete kit".
2) In the State of Colorado's vehicle emissions program, the 8600 GVW rating places the truck under different, perhaps less-stringent emissions performance standards. The test is pretty quick. Emissions testing for this truck consists of inserting a testing probe into the tailpipe and running the engine at idle and about 2500 rpm for a period of time. This is unlike other tests for trucks under 8600 GVW where the truck is run on a dynamometer through a test program.

So, does this make sense?

removing egr gases would do the opposite...make combustion temps hotter...the entire purpose of egr is to cool high temps that cause nox formation.

Thanks for the reply tech2! Very much appreciated.

I bought the truck new in 1989, I am the single owner. The truck currently has 221,685 miles on: original motor, third transmission. It runs great, and I have never had any problems passing emissions testing. A few past SES lights were attributed to other things, not the EGR system.

Regardless, would you recommend removing this small plastic ball from the EGR tube? Thanks for your input.