Please Post a Step -by-Step on How to Clean the Throttle Body [850][1995]... posted by Nathan  on Friday, 23 February 2001, at 3:18 a.m.

               If already posted somewhere- please provide a link.
               I would like to know how to remove ductwork; remove the TB and clean it
               thoroughly with carb cleaner.
               When the TB is removed, will I need new mounting gaskets to get back on?
               I do not believe Bay 13 has directions posted for this operation yet.
               Thanks

               I have never heard of removing the throttle body to clean it. I always just take
               off the throttle body cover and the two hoses and scrub it down with carb
               cleaner. If your car a turbo, or NA. If its NA you might as well replace the
               flame trap. Also the procedure is slightly different between the two cars.

               Nathan,
               If your engine is naturally aspirated, this article may help. It was just sent to the
               VCOA for publication....it includes cleaning the flame trap as well. If you have
               a turbo, ignore these instructions and maybe they will be useful to someone
               else!

            NATURALLY ASPIRATED MODELS...CLEAN YOUR FLAME TRAP!

               We all know that internal combustion engines require a mixture of air and fuel
               to carry on the job of igniting gases, creating mini explosions, and thus turning
               the crankcase that ultimately spins our drivetrain. Turbo engines go one step
               further and add compressed air, allowing for more fuel to the mixture thus
               creating more horsepower. Engines need to breath, and checking your air filter
               is one small item that while important, only begins to address the many items
               that an engine depends on for air.

               Naturally aspirated (non-turbo, or normally breathing) engines found on older
               Volvos including the 5cylinder engines on newer models all share a part, commonly known
               as the Flame Trap. Both my '82 240 and '94 850 share the same flame arrestor,
               and while this little $1.99 part goes largely ignored, it can wreak havoc on
               your engine if allowed to get fouled. Considered part of the crankcase
               ventilation (pollution control), the flame trap is a small part that includes two
               or more hoses, essentially passing gases originating from the crankcase through
               the flame arrestor and back into the intake manifold to be reburned. The
               arrestor is a small round plastic disk about the size of a nickel with many holes
               in it. Looking like an over sized thimble, it prevents gases from igniting in the
               crankcase in the event of a backfire. Earlier arrestors were made from brass,
               they are now replaced with the modern plastic type. My 240 has the newer
               plastic type with matching holder and is identical to the one found on the 850.

               If the flame trap is ignored over time and gets clogged, crankcase pressure will
               build resulting in the following consequences. With nowhere for the pressure to
               go, it will find it's most vulnerable and easiest exit. Seals and gaskets will fail
               resulting in major oil leaks. The oil dipstick has been known to pop right out of
               its holder due to back pressure and owners of 850s have had their rear engine
               seal fail, due to excess pressure. I try to check the flame trap once a year as
               preventative maintenance.

               So where does one find the trap? On the 240 B21A for example, with no tools
               needed, it is found under the intake manifold sitting on top of the oil trap, a
               plastic container like object that is connected to the engine block. The flame
               trap is in line between the oil trap and the intake duct from the air filter.
               Remove the main hose from the oil trap (just pull off) and further up the hose
               you will find a larger plastic housing which is the flame trap. Pull apart from
               the hose and disconnect a second smaller hose that returns to the intake
               manifold and you have the flame trap in your hand. It comes apart in two pieces
               with the flame arrestor sitting inside. Remove and clean using WD40, and a pin
               to poke the holes clear. If your trap has never been upgraded to the newer
               plastic type, this is the time to replace it. Another option to cleaning is the
               small price to replace with new. On the 850 for example, I replaced the holder,
               O-ring and trap (three parts) for less then $10! The local dealer had all parts in
               stock.

               On the 850 the same sort of thing is found, but this time you need tools!
            Remove the air duct that runs from the air box to the throttle body. This is done
               by loosening two straps on either end. At the throttle body you will find a
               plastic housing attached also by a strap. Leave attached, but on its side you
               will find the flame trap. Simply take hold of the round plastic holder (with
               attached hose) and turn counter clock a twist of the wrist and the holder will
               disconnect from the body. Take apart and clean. If you are going to this much
               trouble on your 850, now is a good time to clean the throttle body as well. A
               sticky gas peddle is a good indication that the throttle needs cleaning. To get at
               the throttle body, remove the top cover that is held in place by one #25 torx
               screw. This is the plastic cover where the throttle cable seems to disappear
               into. Now remove the plastic housing previously mentioned where the air duct
               attaches. It removes from the throttle body by loosening a strap. With the
               throttle now in full view, clean the body. With jobs complete, replace all parts
               in opposite order.

               Tony Giverin, 2001

               --
               Tony G, '94 850GLT, "82 240DL (mint) July '99 "Rolling" cover