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

install the new valve, without the nuts. Attach the valve to the air-diverter post and
replace the lock piece. Next, replace the nuts on the new vacuum valve. You may
need to use some masking tape inside of the socket to hold the nuts in place to
prevent them from falling out. Be careful putting these nuts back on as the plastic
studs may break.
I am now going to assume that you have broken one or both plastic studs on the
vacuum valve. You will need to fabricate a bracket, as noted in picture #4. Bracket
material is the same material as used to mount car radios. This has multiple
perforations and is fairly easily bent. Tom Irwin experienced breaking both studs and
fabricated a bracket which held the valve on by going over the vacuum valve. The
bracket had a hole in the center, which was enlarged, to go over the center hole of the
vacuum valve. The bracket was attached to the air-box by using small screws. The
bracket I used had a small bolt going through the box. Make certain that wherever
you mount the screws that they cause no interference with the movement of the
diverter in the air-box.
Attach vacuum hoses. Start the car, and check that the valve works properly by
moving your heating-air-conditioning controls. If all is well, clean up the edges of the
flaps which were cut, bend them back into position, and use J-B Weld or a similar
product to hold in position. Next, use the black RTV-silicone sealant. Do not use too
much as it could interfere with inside air-flap movement! After the sealant is dry, you
may desire to put duct-tape over the entire incision. You will note in Picture #6 the
reassembled unit minus the duct-tape. This has worked well for us during the past