Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

equipped, the EGR valve is now “exposed”, behind and to the right of where the IAC was.
It is connected to the inlet manifold via a steel tube that connects to the side of the valve.
There is another steel tube connected to the end of the valve, that runs around the back
of the block, to the exhaust manifold. Remove it and the EGR valve bracket on top of the
base of the breather box Remove the two 12mm hex bolts that attach the breather box to
the block. These can be removed with a box wrench or a socket and there is now plenty
of space under the manifold to get at them directly. There is a bracket supporting a wiring
harness clip in front of the block at this location. Remove two 10mm hex bolts attaching
the bracket to the wiring clip. One is front and center relative to the breather box, the
other is to the right of the breather box. Pry the bracket away from the wiring clip and it
will pop off. Now is the time to wipe dirt away from the area surrounding the box. Use
brake cleaner spray and a rag or brush and remove as much as you can so that when the
box is removed, you don't push dirt down into the crankcase through the opening.Lift the
breather box up away from the block. Rotate it forward slightly when it raised ½ inch or
so, so that it clears the heater hose (this is connected to the block slightly above the
breather box) and it will come free and can be maneuvered out easily. Caution: there is
a hose inside the block into which is fitted a 3/4 inch long lip on the bottom of the
box. This hose goes back down to the sump, and is held in place with clips. When
removing the box, be careful to NOT disturb or yank this hose: gently pull the lip
out of the hose. There's an O-ring where the box fits against the block -remove this
carefully as it may be brittle.Cleaning the box. Use a solvent or degreaser that won't
attack plastic, such as Gunk Motor Flush, citrus-based solvent, non-chlorinated brake
cleaner. [Paul Seminara:] Soak it in Naptha thinner for a day. Follow with a soak and
scrub with Simple Green (straight), hot water rinse and dry. [John Sargent/Randy
Starkie] Air will flow quite freely through a clean oil trap. If you want to clean it up instead
of buying a new one, try probing inside with a piece of wire to break up the deposits. I
have found that a lot of deposit build up occurs around the top opening. An initial reaming
out by hand with a 5/16 or 1/8" drill bit will remove a lot of the crud. There are no check
valves inside the oil trap, just a baffle or two. Carefully clean the bottom surface and oring
groove with rag and cleaner. Install new O-ring (which will be green and fit nicely).
Smear some general purpose grease on the o-ring to hold it in place while re-installing
the box. Before beginning to re-install parts, clean up the exposed surface on the block
where the breather box sits. This area is usually something of a dirt trap. Be careful not to
knock any crud into the openings into the crankcase. Also, while you are doing this, take
care not to disturb the oil return hose (front opening). Carefully wipe around the larger
opening, and then (even more carefully) around the smaller opening that has the oil
return hose inside it. Then spray a little throttle-body cleaner onto a clean rag and wipe
the surfaces again. This is the sealing surface for the breather box o-ring, so it is
important not to leave any dirt.
2. The rest of the re-installation process is (as they say) a reverse of the removal process.
Apply a little dielectric grease to the contacts of the IAC solenoid and EGR before reconnecting
them.