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Technically no, but you do have what is known as a "flame trap". The following article will tell you eveything you need to know about it.
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.
Now both you and your engine can breath a sigh of relief!
Tony Giverin CVC/VCOA
March, 2001
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