EGR Cleaning

[Tim Rogers]

Mark wrote:
>>I don't know how expensive it would be to replace the whole EGR tubing,
the
big and the little tubes are connected and no way to separate them. It's the
little one that runs to the BPT that gets blocked by carbon build up... you
can't just take that one off. At any rate, in order to replace it with a
whole new system, you'd still have to get the old one off... huge PITA.<<

You should never have to replace the tubing, but you very well may have to
remove it to unclog the small tube.
Here is the general procedure:
Remove the distributor, valve cover breather hose and the PAIR valve
assembly if so equipped.  Removing the coil might also make things a bit
easier.
Spray the flare nut at the manifold / EGR tube junction with PBlaster or
other Liquid Wrench type penetrating oil.
Remove the BPT hose.
Undo the two (10mm?) bolts that attach the large tube to the intake
manifold.
Using a 24mm wrench, undo the flare nut at the manifold.
Now you can take off the tube and see that the pinhole (yes, it really is a
pinhole) that leads into the BPT tube is blocked up.  You might be able to
open it up with a dentist's pick. You can use a very small drill bit and
drill the hole open just a little so that the hole will be less likely to
clog in the future.
If you drill the hole too large, too much of the exhaust heat will get up
the tube and may lead to damage of your BPT valve.
When replacing the tube, put the flare nut on first, but do not tighten
until you get the other end's bolts started
I know the removal procedure pretty well as I did it Friday night while
taking off my head.
The broken timing chain that I caused resulted in both the cylinder #2
exhaust valves being bent, so I am porting, polishing and port matching a
new head to take its place, should be on in time for the convention....

Tim Rogers
-93 NX T-top -needs motor work
-91 NX - Racecar-to-be
-75 Silverado - Rusty Beast
-01 Astro - Work Van, Tow Beast