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Thread: This is getting bloody annoying...

  1. #31
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    Quote Originally Posted by Tins View Post
    Hmm. Let's look at a hypothetical. A 2.5 litre engine, doing say 1800 RPM, might be drawing maybe 200-250 CFM, ( Hypothetical guys ) . That is air, dust, smog, smoke insects, and, importantly, water, per minute.

    Now, said diesel could be driving the cart at 100 km/h. The engine is hungry for air, and draws it in rapidly. There is probably a measurable vacuum in the intake tubes ( not the manifold, I know that ) Let's now say that it is raining, heavily, like North Qld in the wet.

    We have a car driving into this rain at 100 km/h. The engine is drawing it's air in through this:
    Attachment 159098

    but all the water ejected is exiting through this?:
    Attachment 159099

    It's a nice theory, but I don't buy it. Those slots are for installation purposes.
    I have 4! yes four slots. You could be right. It would be interesting to see how much water enters the intake. Litres per minute and how quickly water exits through the slots. In heavy rainfall. How many drops per cubic metre? volume. Any numbers? 1%? 3%? at 100kph or 27.8 m per second, you are looking at 0.108 cubic metres per second, swept by the intake. With 10% of the air occupied by rain drops, you have 0.0108 cubic metres of water per second. Which works out at 0.0000108 Litres per second., about 1 500th of a teaspoon per second. So the amount is close to nothing. 250 CFM is about 0.12 cubic metres per second, slightly more than is being rammed into the air intake.
    Or is it 10L per second?
    It is late and I have 2 vastly different numbers. I need to sleep. Back tomorrow. Further research is required.
    D2a Td5 Manual, Chawton White. aka "Daisy"
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  2. #32
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    Quote Originally Posted by Tins View Post
    All good in theory. I'm aware that the snorkel manufacturers say that in their blurbs. But it doesn't explain why I find all the contaminants I mentioned, including water, in my airbox.

    But this is now way OT. Could the air filter have become wet enough to do what it did by the car idling in a car wash is the question.
    Yes and no.

    The airfilter will rupture for a couple reasons.

    due to age, being blocked, and the very poor design of the airbox, the use of inferior quality filters ( Mahle,Mann, and genuine seem ok) .

    I have also seen td5 filters that in my opinion were very close to letting go due to excess moisture getting on them.

    If the filter pictured got wet at the car wash with the engine idling, (and water being directed indiscriminately) it would be fine....until highway speeds are introduced, by which time the combination of the water soaking in and softening it, and then with increased air draw from the motor, it could easily do what is pictured.

    Cheers
    James

  3. #33
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    Ok. I had a safari snorkel on mine for years. Belted through torrential rain at +100kph and drove through smaller creeks without slowing, i.e. slight aquaplane with that sound like the underside is a hull on a river. Never had an issue with water into the air filter. I did sometimes reverse the head in scrub as it would collect leaves and at speed the grill gets broken. I do believe the slots let the water out as the water is not filling the intake by any means, and being denser hits the rear of the head and is forced out the slots. Sure, there could be a mist that gets down but never enough to destroy the filter.
    I did have my intake thoroughly siliconed with all the breathers piped back to it for wading. IE on installation took it all apart for this.
    Have you sealed up the duck-billed valve in the mudguard? It allows water to drain in the standard system but can get damaged and allow ingress.

  4. #34
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    Have you sealed up the duck-billed valve in the mudguard? It allows water to drain in the standard system but can get damaged and allow ingress
    The duckbill is designed to close with the slight vacuum of the intake while the engine is running and open while stopped to let any water out. You can test it by sucking on it.

    I bought a new one recently as they are still available.

    There is another hole in the bottom of the filter housing that should be closed IMHO.
    Regards PhilipA

  5. #35
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    I got a forward facing snorkel inlet, never had a problem with water, in the 4 years I've had the car.
    Only issue I see is lots of bugs collect in the air box.

    Brother did have a slightly damp air filter on one change tho(in his D2 TD5). No reason for it. Can't remember rain for any period before the service either, but maybe it did.
    His is also a forward facing inlet, but it's moulded as the entire unit, not changeable like the Safari type. So no option to make it rear facing unless the snorkel tube is 'cut and shut'
    I think it's a TJM branded snorkel, so you'd think that the company would be confident that rain/water wouldn't be an issue with forward facing vents.
    Arthur.

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  6. #36
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    I can't find a scientific explanation what's going on in the snorkel but i recorded live data on a friend's Td5 with snorkel turned both ways and the MAF - MAP relation was slightly better at high speeds with it turned backwards that's for sure
    Discovery Td5 (2000), manual, tuned

  7. #37
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    Quote Originally Posted by Tins View Post
    Hmm. Let's look at a hypothetical. A 2.5 litre engine, doing say 1800 RPM, might be drawing maybe 200-250 CFM, ( Hypothetical guys ) . That is air, dust, smog, smoke insects, and, importantly, water, per minute.

    Now, said diesel could be driving the cart at 100 km/h. The engine is hungry for air, and draws it in rapidly. There is probably a measurable vacuum in the intake tubes ( not the manifold, I know that ) Let's now say that it is raining, heavily, like North Qld in the wet.

    We have a car driving into this rain at 100 km/h. The engine is drawing it's air in through this:
    Attachment 159098

    but all the water ejected is exiting through this?:
    Attachment 159099

    It's a nice theory, but I don't buy it. Those slots are for installation purposes.
    Nope. Those slots are for drainage.

    Rain filled air is not 100% water. Not even 10%.

    On both defenders, my D1, my D2 and our D4 we have never had a wet air filter.

    That includes hours in torrential rain, massive puddles splashing over the front of the roof... or car washes when I would use them.

    To get the volume of water to do that you’d need someone spraying water directly into the intake for a couple of minutes.

  8. #38
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    Quote Originally Posted by sierrafery View Post
    I can't find a scientific explanation what's going on in the snorkel but i recorded live data on a friend's Td5 with snorkel turned both ways and the MAF - MAP relation was slightly better at high speeds with it turned backwards that's for sure
    When you say better, what metric are you referring to?

  9. #39
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    Seriously guys Old mate has a stuffed air filter element So Simply replace it with a "Quality" air filter and enjoy the D2 experience
    Many of us do a "Pre Start" on our 16/20 year old Disco's AND that includes replacing the air filter at a regular interval along with servicing and regular maintenance, **** happens if you drop the ball
    You only get one shot at life, Aim well

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  10. #40
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    Quote Originally Posted by Tombie View Post
    When you say better, what metric are you referring to?
    I mean the MAF - MAP readings relation for example if we consider a good relation under load to be MAF=600 -> MAP = 230 with snorkel backwards and with it the other way at the same load MAF = 610 -> MAP = 220 and so on along the whole reading range, these are not exact figures i just remember the behaviour ... i'll dig if i can find those logs but quite unlikely as it was years ago and i didnt give them a name ... the conclusion is that the way the snokel head is turned has a slight effect on the air flow and IMO it's better to be turned backwards
    Discovery Td5 (2000), manual, tuned

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