Just curious, I have read about the flametrap problems with this model car. After talking to my mechanic, he seems to recommend changing only the PCV valve. Not the Flame trap itself as it could be very costly.
Does the flame trap itself need to be replaced or just inspected?

96 850 N/A 185,000 KM

Had it since new and no major problems so far.

Thanks all for ellaborate responses. I will take the precautionary approach and service it. After having going through this board, I realize that the 850 seems trouble prone. I guess I have been lucky so far: only A/C (changed under VIP extended warranty and the ABS problem, again caught under the VIP extended) That's it in 7.5 years of ownership. I don't know if that makes a difference, but I have the plain "vanilla" 850 GLE 5 speed (10 valve), less things that could go wrong?

I think your ownership experience is probably along the lines
of what most people experience.

By the way, the flame trap is pretty easy to clean out yourself
(no new parts required) following the steps at this site:

http://volvospeed.com/Repair/ftrap.htm

Flame trap is a 60-cent item which takes about 15 minutes to replace.

My dealer refused to sell me a flame trap as Volvo recommends it be removed! If you check I believe you will find that there is NO PVC valve

When inspected, you might as well replace. The part is only a buck or two. Keep an eye on it though... I learned the hard way--- $1,100 rear main seal job.

Your car may well try to warn you on this issue. The check engine light on mine came on and the dealer said replace the flame trap. We'll see if this fixes it. I'm letting the dealer do it only because they're doing it free.

Flame trap itself IS cheap. I'm not really sure what it does tho.

Could someone clear up what the flame trap does
and how to replace it,

it sounds like the weak link of the car, among other things

I'm working from memory here . . .

. . . it's just a piece of Nylon, about an inch in diameter, about a half-inch thick, perforated with dozens of 1/16" diameter holes. On one side of the flame trap is the intake system (under vacuum) and on the other side of the flame trap is the crankcase. So, this passageway is obviously used for crankcase ventilation.

What happens is, over time, these 1/16" diameter holes clog up with burned oil, etc. So the flame trap ends up becoming a plug. Crankcase pressures go up and you blow out various seals. Because this 60-cent part becomes a plug, you end up blowing out your rear main seal, which will probably case $800+ to replace.

My guess is that the purpose of the flame trap is to "breaks up" a flame which may originate in the crankcase and prevents that flame from propogating into the intake system, or possibly, visa-versa.

Regardless, manufacturers don't include parts labeled "flame trap" just for the fun of it. It is likely, that during testing, Volvo determined that there was a certain risk of a fire propogating through various parts of the engine. To prevent this possibility, they included this flame trap.

Unfortunately, this flame trap has become a weak link in maintenance of the 850. And certain dealers probably think that the risk of a fire is so low, and the risk of pissing off customers, because of the failure of a 60-cent part, so high, that they simply remove the flame trap.

I think I would rather keep the flame trap in-place, to protect against the possibility of a fire, but make sure that I replace, or clean, the flame trap on a regular basis.

Within the engine crankcase (not the cylinders) there is air,oil and maybe a little blowby from the burning of gas. So as not to polute the atmosphere this can be retuned to be burned A small screen looking like a thimble with holes (a strainer) is placed in front of the throttle plate. Should this get clogged, pressure build up in the crankcase will cause the gases,oil to seek another way out (rear main seal) to releive the pressure.Should you also have a backfire the screen should prevent an internal burning of any unburned fumes.A PCV (if it had one)would return the same gases but would be located in the intake manifold.

Ken and Jot have this correct. I always have the flame trap serviced on my non-turbos (The turbo doesn't have one) and I've cleaned it myself a few times. When getting it serviced, some mechanics clean the little nylon screen, which really cannot "wear out". I just had my son's non-turbo serviced this week....bill says "Flame Trap Kit", $12.75. Having had this screen out myself, I have no idea what the "kit" is. The crankcase ventilation works fine without this little trap, and the risk of a backfire in a volvo seems minute. I've considered leaving the screen out. It seems that if you are not going to check it every 10,000 miles and clean it, the next best option is to take it out to avoid pressure build up.

I Already had my flame trap servied on my 97 850 however
my 93 850, I am planning to take out,


any thoughts or worries??