Greetings all-
Was gonna use the IPD flame trap kit on mine awhile back and my mechanic said don't bother, that on my car ('93) I could just take the trap out altogether. I get the idea that the trap makes a difference on the earlier 240's but on my '93 is it just worth leaving it out? I've never had any backfire problems and my car is running really great right now. Makes me wonder since Volvo ditched the design just a few years later... correct?

if the flame trap perforated plastic thingy was an essential feature then why are they absent on the more recent volvo's? you won't find them on a v70 to cite merely one example.

other than an extra cylinder and aluminum instead of iron for a block someone tell me why they don't have a plastic perorated thiny in the flametrap?

have backfires become extinct in the newer fuel injected volvo engines?
if they have someone tell me how they have accomplished this that is actually different than the b230 engine?

True. The last year for flame trap screens was the 98 S70/V70's. That, most likely, was the last year for the screens in any model Volvo.

Hi Delco,

Are you referring to IPD relocation kit?

http://www.ipdusa.com/products/5823/106506-flame-trap-relocation-kit-lh

FYI.

My 87 model had the flame trap located down below by the oil separator, I bought that kit and relocated the flame trap near the intake manifold for easy service. Your 93 model doesn't need that kit/upgrade at all. You already have it.

My car is MD right now (waiting for heater core) so I can't take pictures to show you but my flame trap does not clogged after putting lots of miles. I use Mobil 1 synthetic oil, change every 5000 miles with almost no oil loss. I don't need to fill up in between and the oil level looks good to me during that 5000 mile interval. I am planning to take it up to 7500 miles at some point. If you keep up with your oil change, I think you should be just fine.

I will take a picture + give you the exact miles later.

If they are removed, what happens to all the plumbing and oil recirc box on the side of the box?

They are talk about the actual perf plastic disc (formerly a brass screen) inside the holder. Designed to stop carb fires going into the crankcase...not really relevant anymore.

hi sages- not sure im following on the rationale here behind saying the flame trap can be eliminated due to crank case fires possibly being caused by carbs which cars dont have any more. crankcases need ventilation to reduce pressure built up by oil fumes and blow by gases from the combustion chambers. most american cars either had an open pipe to the atmosphere to vent these gases but that was replaced by pcv systems which had a valve to sense the buildup of pressure in a running engine and route them back to the throttle plate on the carb to be burned in the cylinders . about 63-64 the pcv systems came in and prevented venting to the atmosphere(a no no with increasing concerns for emissions). if you eliminated the frame trap in the volvo 240 which my 92 has you would still have to route the crankcase gases to the combustion chambers or the pressures would cause seals to leak oil correct? thanks tons oldduke

The flame trap itself is just a piece of plastic with some holes in it (or a brass screen in earlier 240s) wedged in the PCV path. Removing that little piece of plastic will not affect the crankcase ventilation in any way (unless, of course, the thing is clogged, in which case it will improve ventilation).

Nobody has mentioned it, but supposedly Volvo themselves released a technical service bulletin suggesting that techs remove the flame trap and NOT replace it; the possibility of a fire is almost nil, but the possibility of a clogged flame trap blowing out oil seals fairly high.

Just for discussion -- I'm trying to understand this. What about fuel injection has made the flame trap irrelevant? The only difference I can think of is the float valve in a carb might be a little less resistant to the pressure wave and flame front from ignition when an intake valve happens to stick open, or ignition occurs at the wrong time. How does that affect the communication with the crankcase and its volatile mixture?

A rumor of a service bulletin removing the flame trap? That we should look into. Figuring Volvo to have a few lawyers around, I can't think they'd be more sympathetic to poor oil change habits at the expense of safety. I'm saying that with a rather fresh memory of EZK screwing up and hearing that pop through the carburetor - er - throttle body that causes me to cringe. Yes let's find that service bulletin...
--
Art Benstein near Baltimore

Milt Famie was a pitcher for the Cubs. Unfortunately, he had a great fondness for beer. After walking several successive batters in the 9th inning, the manager of the opposing team turned to one of the batters asking what that was all about. Said the batter "It was the beer that made Milt Famie walk us."

Art, here is a link to an old post by FitzFitzgerald, whose advice I always trusted; it may be the source of my belief in that TSB: http://www.brickboard.com/RWD/index.htm?id=1107930

The pertinent bit is right at the end: "...don't ever install the little screens in the flame traps. There's a Volvo Technical Service Bulletin that advises discontinuing their use. Their purpose was to keep a backfire from going from the intake manifold backwards into the crankcase and igniting the oil vapors, but when was the last time you heard a fuel injected engine backfire? The screen is only useful on the carb'd engines which we didn't get in the US markets."

A search turns up many posts referencing the Technical Service Bulletin from Volvo, but I have not yet found actual proof. Could this be another forum rumor that has been repeated so many times it is considered fact?

Good discussion, and I've had many with Fitz in the old days. But he doesn't explain why a malfunctioning carb'd engine is more likely to ignite fuel in the intake manifold than one fuel injected. And I've heard them do exactly that, cringing while imagining that fragile platinum wire. Nor does anyone say why the flame trap's plumbing -- specific to the fuel injected configuration -- wouldn't have deleted the insert in those many years since FI was introduced. Not buying it until I see it, and yes there are plenty such myths created on these boards and propagated ad infinitum. Some ARE created by Volvo Tech Pubs.
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Art Benstein near Baltimore


A thief broke into the local police station and stole all the toilets and urinals, leaving no clues. A spokesperson was quoted as saying, "We have absolutely nothing to go on."

Well, I certainly agree that a FI car is capable of a backfire, and not being very familiar with carburetors, I couldn't speak to the likelihood being less (or not).

I admit to taking some long-time forum members at their word, mentally recording the Brickboard gospel, especially when I was just starting out with my 240s. For instance, until recently, I still held tightly to the lore that says the coolant draincock is always seized, and you better not use it.

Even in the event that we find a TSB confirming Volvo's exhortation to toss out the flame trap screen, I think it is, as you say, a personal choice. But I would like to find that TSB.

The service bulletin, or link to it, was posted here a long time ago. Maybe even 10 years ago??

Volvo suggests removing the screen only as mentioned. Not the entire plumbing. FWIW - I tossed the screens on both 240 and 850 years ago with no ill effects...

I just now re-read your post and have a question.

"The service bulletin, or link to it, was posted here a long time ago. Maybe even 10 years ago??"

Can you find it? Are you sure? You sound sure.

"I tossed the screens on both 240 and 850 years ago with no ill effects... "

I'm not surprised. Conversely I've kept mine in place also with no ill effect.

Sounds a lot like this is a debate much like the personal choice to wear your seat belt or motorcycle helmet -- either side can drum up a plausible argument. Many have ridden bareheaded with "no ill effects."

But I really don't care if you choose not to use the device, I'm interested in this rumor of some Volvo TSB suggesting its removal.
--
Art Benstein near Baltimore


2. Evidence has been found that William Tell and his family were avid bowlers. Unfortunately, all the Swiss league records were destroyed in a fire, ...and so we'll never know for whom the Tells bowled.

The plastic screen that is. I did so to decrease crank case pressure, seems to have worked. My leaking rear main has slowed to a barely perceptible weep from a dime sized spot on the ground overnight previously. No ill effects.

hi sages- read the recent posts hereto. lets think this out a little more. crank case ventilation is cessary in all internal combustion engines i think b/c the pressure generated must be relieved to avoid pushing oil through the oil seals. dont think this has anything to do with whether engine is diesel, carbed or fuel injected. venting to the atmosphere is out so that leaves a pcv valve or direct venting(volvo 240)to the intake manifoldto burn these fumes.if you remove the screen venting would beimproved... still have to keep the orifice clean which allows these fumes to enter the intake manifold for burning. the screen would seem to be detrimental since its one more thing to clog up and if it does, to wit- no crankcase ventilation to reduce pressure. old fuds here like me ought to remember the road draft tubes on pre 63 american cars which vented directly to the air. once had a 53 ford flathead v8 which burned oil until i rebuilt it. coppers used to stop me for too much smoking from under the car. one called me a public nuisance. would like to hear from any old fuds here regarding my analysis. thanks tons oldduke

Welp,

The combination of a fully leaking fuel rail pressure regulator into the air intake. Or a leaking cold start injector. Or really faulty conditions that may induce back fire into the air intake. What if the valve timing or ignition timing is off causing pre-ignition (I may have that backwards).

On an engine without the flame trap sieve (screen) ...

No, I'll keep that PCV flame trap right where it is. I may relocate it if an early LH-Jetronic 240/740. But I'll always inspect that PCV flame trap that it breathes freely regularly.

That sieve, or screen, breaks up the flame body and may prevent what could be a really disastrous of a back fire into the air intake that travels into the sump (oil) chamber.

Consider the oil condition if dirty, full of moisture, or filled with unburnt accumulated gas. Marry that condition with a full flame back fire through the air intake port, and you may have more than a mess.

Yeah, I'll always keep that PCV flame trape sieve right where it is and always breathing freely.

Of course, it does beg the question why the turbos went without a PCV flame trap sieve, considering how fuel to air ratio rich the first turbo redblocks were tuned to perform. I'd imagine turbo+K-jet would be more likely to back fire into the sump with some unpleasant outcomes.

Any of you ever look at the PCV systems on other autos? They use different solution for a flame trap, yet they can all get clogged somehow. Certainly if using mineral engine oil and driving it for short runs almost daily.

I'm just spectulatin'.

cheers.

Onward MacDuff.
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Happy Friday Everybody! I love kitty-kats!

Being that Volvo uses a "fixed orifice" system as opposed to a "variable flow" system, there is no "retractable pintle". Isn't it this pintle which effectively closes off any return pressure in case of a backfire? The open nature(lacking a hard mechanical stopping mechanism) would seem ill suited to anything but regulation of crank case pressure. I am no engineer but that plastic screen would seem unlikely to buffer the back pressure significantly compared to a pintle being forced back into its seat. Just thinking aloud here...

"When the engine is off or it backfires, spring tension closes the valve completely preventing the release of blowby into the intake manifold. The valve closes during a backfire to prevent the flame from traveling into the crankcase where it could ignite the enclosed fuel vapors"

Source: http://www.autoshop101.com/forms/h63.pdf

Knowing nothing about Volvo-post-Ford, are those motors (that don't have flame traps) designed by the same company? Are they designed with the same plumbing but minus the screen? I doubt it.

Clogged PCV valves seem part and parcel to the recollection of my pre-Volvo days, speaking of pintles. Isn't that what everyone else uses?
--
Art Benstein near Baltimore

Back in the 1800's the Tate's Watch Company of Massachusetts wanted to produce other products, and since they already made the cases for watches, they used them to produce compasses. The new compasses were so bad that people often ended up in Canada or Mexico rather than California . This, of course, is the origin of the expression,..."He who has a Tate's is lost!"

invariably i remove all flame traps on 240/940 cars i run across. fuel injected cars don't really need them