Flame trap/breather
Discussion
Ian...Do yourself a favour and buy a new one mate..Diverting the crankcase breather will cost you probably more than a new flame trap ..Wire wool might not be up to the job as they would of used this if it was...Also its all well and good diverting the oily air but what about the coating thats already in there?..You will need to thoroughly clean the plenum internally to make a difference so please just buy a new one...Cheers ...Ziga
http://www.ebay.co.uk/itm/Rocker-Cover-Flame-Trap-...
http://www.ebay.co.uk/itm/Rocker-Cover-Flame-Trap-...
Edited by mrzigazaga on Wednesday 29th January 13:10
You may well see a small power improvement by diverting - how much depends on how much wear the engine is suffering from. The coating in the plenum isn't really a problem so much as actual oil vapour/exhaust gases in the air being drawn in with the fuel charge. But even if you divert the gasses away from the intake, as Mr Z says, you should still use a flame trap.
Clean air is best, clean dense air is even better!
Clean air is best, clean dense air is even better!
maston said:
Question, will a grubby (just had a look and it is really really oily !!!) effect the running and cause a misfire at high revs ???
I doubt it. What will cause a misfire at high revs, assuming everything else is in order, is a spark jumping from the high tension leads to an earth. Run the car in the dark at night with the bonnet up and rev the engine and look out for jumping sparks. Keep leads well away from each other and from engine block and any earth. (or possibly an arc line inside the distributor cap running down to distributor body) Good luck.Tony. TCB.
adam quantrill said:
I pull the gauze out of mine, dunk it in petrol, wash the crud off and stick it back in. Takes about 10 minutes and saves 17 quid for better uses...
That is the best solution, by far.Under normal circumstances with a sound engine, crankcase pressure is pretty much neutral.
The breather from the plenum spigot is under constant mild suction so the crankcase gasses are continually being withdrawn. The crank case pressure is compensated by the 40 thou hole in the small breather at the rear of the LH rocker cover.
The coarse mesh oil catcher in the flame trap, is best kept clean because the gasses pass right through allowing any oil mist from the crankcase to condense (sort of) on the CLEAN metal mesh and drip right back into the crankcase via the rocker drain holes.
The foul air carrying small particulate impurities including any unburned fuel that does get into the crankcase is routed back through the intake to be re-burned.
Obviously that also takes care of any environmental issues too.
The amount of oil deposited in the intake tract is therefore relatively small.
HOWEVER, with an unsound engine, much more carbon contaminated blow-by is likely to occur, the coarse wire filter will need cleaning more often to do it's job properly and there will be an increase in muck deposited in the intake channels.
Either way, with a good or a less-good engine the proper solution, IMHO, is to routinely remove the air intake hose for visual inspection and/or cleaning of any grot on the throttle plate and in the tunnel thereabouts, along with cleaning the coarse mesh filter.
I guess it goes without saying that a routine inspection of the 40 thou breather hole is also needed.
The frequency of the breather inspection/cleaning program is determined by the soundness of the engine, but because it is so easy to do, annually would be a good idea.
Thinking about it, as most owners hardly ever/never do it, the causes only come to light when the engine starts to misbehave due to blocked breathers plus a ton of carbon crud deposits inside the plenum chamber along with idle speed hang-up and enriched idle mixture due to the loss of breather air.
Worst of all. A totally blocked breather leads to build up of crankcase pressure, oil squirting from bearing and gasket seals and eventually - I guess, engine damage.
YKIMS.
Whilst this is being discussed, would this being dirty/blocked cause (or make worse?) a positive pressure in the crank case?
I'm still not convinced all my breather pipes are in the right places.
I have a slighty positive crank pressure which seems to get worse with higher temps or "pushing" the engine. (Runway runs at Dunsfold for example) On occasions it is enough to push the dip stick up slightly (just enough to break the "seal" between the dipstick and the tube) and occasionally I get a dribble of oil from the top of the dipstick as well.
Car seems to run fine other than this in normal use, but it does seem to "run out of steam" at higher revs in higher gears
I must have an inspection soon as suggested above.
I'm still not convinced all my breather pipes are in the right places.
I have a slighty positive crank pressure which seems to get worse with higher temps or "pushing" the engine. (Runway runs at Dunsfold for example) On occasions it is enough to push the dip stick up slightly (just enough to break the "seal" between the dipstick and the tube) and occasionally I get a dribble of oil from the top of the dipstick as well.
Car seems to run fine other than this in normal use, but it does seem to "run out of steam" at higher revs in higher gears
I must have an inspection soon as suggested above.
wedgeinald said:
Whilst this is being discussed, would this being dirty/blocked cause (or make worse?) a positive pressure in the crank case?
I have a slighty positive crank pressure which seems to get worse with higher temps or "pushing" the engine. (Runway runs at Dunsfold for example) On occasions it is enough to push the dip stick up slightly (just enough to break the "seal" between the dipstick and the tube) and occasionally I get a dribble of oil from the top of the dipstick as well.
Hi Mate...Its always good for an engine to breathe properly, Have you checked the operation of the PCV on the O/S rocker cover...They can get a little gummed up and a clean out with some brake & clutch cleaner is good, The mesh inside the oil filler cap needs a clean from time to time.I have a slighty positive crank pressure which seems to get worse with higher temps or "pushing" the engine. (Runway runs at Dunsfold for example) On occasions it is enough to push the dip stick up slightly (just enough to break the "seal" between the dipstick and the tube) and occasionally I get a dribble of oil from the top of the dipstick as well.
Also mine used to push the dipstick up a little but that was due to an ill fitting dipstick..I found a Sierra one to be better sealing but did need to nip a little off the end and re-mark it....This happened pre-blower days but post was a different matter...The oil filler neck should pull in air which is being sucked through the plenum creating a directional flow...High Crank case pressure can blow crank seals, Especially the front one.
wedgeinald said:
I'm still not convinced all my breather pipes are in the right places.
Essentially there is only one pipe and that connects the plenum to the rocker cover via the PCV valve...The fitting on the plenum to which the pipe is connected is like a long tube that can also get gummed up so that is worth removing and checking also.Cheers...Ziga
The flame trap itself would take an immense amount of gunge before it blocks up. As Zig says - check the pipes themselves - I had the long one block. Easiest way to clean the long one is to cut in half then use a 15mm copper tube to join the two halves.
The gallery into the plenum is prone to blocking too and when this happens you'll get positive pressure. This is a right pig to clean out but I have had some success blowing a thread through it, then pull a string through. When you get thick string through tie a rag to the string and pull that back and forth with some petrol to clean the gunge out.
The gallery into the plenum is prone to blocking too and when this happens you'll get positive pressure. This is a right pig to clean out but I have had some success blowing a thread through it, then pull a string through. When you get thick string through tie a rag to the string and pull that back and forth with some petrol to clean the gunge out.
wedgeinald said:
Whilst this is being discussed, would this being dirty/blocked cause (or make worse?) a positive pressure in the crank case?
I'm still not convinced all my breather pipes are in the right places.
I have a slighty positive crank pressure which seems to get worse with higher temps or "pushing" the engine. (Runway runs at Dunsfold for example) On occasions it is enough to push the dip stick up slightly (just enough to break the "seal" between the dipstick and the tube) and occasionally I get a dribble of oil from the top of the dipstick as well.
Car seems to run fine other than this in normal use, but it does seem to "run out of steam" at higher revs in higher gears
I must have an inspection soon as suggested above.
Norman - worth checking all your pipes are in the right placeI'm still not convinced all my breather pipes are in the right places.
I have a slighty positive crank pressure which seems to get worse with higher temps or "pushing" the engine. (Runway runs at Dunsfold for example) On occasions it is enough to push the dip stick up slightly (just enough to break the "seal" between the dipstick and the tube) and occasionally I get a dribble of oil from the top of the dipstick as well.
Car seems to run fine other than this in normal use, but it does seem to "run out of steam" at higher revs in higher gears
I must have an inspection soon as suggested above.
Colin (Taff_o) was telling me that he has just had a lot of work on his car and engine
and Phil our mechanic (and SEAC owner) said some of his pipes were wrong
Cheers
Trickie
maston said:
what should I make sure is really clean and clear
- flame trap innards
- replace coarse wire bundle if it wont clean up shiny
- 40 thou hole and filter on LH rocker cover
- crossover pipe from flame trap to plenum breather inlet pipe
- plenum breather inlet pipe gallery to inlet tunnel (not easy - must be completely clear)
- inlet tunnel and throttle plate
- plenum chamber innards (if it is dirty inside)
(whilst at it, if/whenever plenum top is removed)
- be sure to clean idle air gallery and various air/vacuum pipes/stubs/holes
- throttle plate mechanism, bearings and spindle seals
- overrun valve plate/spring
- brake servo non-return valve on the trumpet base
- inspect for secure rubber pipe fittings
- check for split/damaged rubber pipes
- air rail metal pipes
“Look after your Plenum and your Plenum will look after you!”
Edited by honestjohntoo on Tuesday 4th February 13:50
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