Thread: LEAKY PUMA AIR BOX !

I like the logic of that test!!

Not sure if a plastic bag would be strong enough to stall the engine, as I suspect that with a perfect seal the bag would have holes sucked through it, but a good test idea.

Will be watching with interest!

Originally Posted by spudboy

I like the logic of that test!!

Not sure if a plastic bag would be strong enough to stall the engine, as I suspect that with a perfect seal the bag would have holes sucked through it, but a good test idea.

Will be watching with interest!

Just out of curiosity, I tried the plastic bag test over the snorkel of my 300tdi. I have heard of this method of testing before.

The bag was very quickly sucked onto the snorkel and formed a pretty good seal over it. It didn't make the engine stall BUT I'd confidently say mine is all sealed well, the exhaust started to show some carbon being spat out, and the intake air tubing from box to manifold got very well flattened together. No noises from air being sucked in from around the seal of the air box or any joins, I think it still just manages to get enough from around the snorkel head. Whilst it didn't suck holes into the plastic bag, I think if I'd left it a little longer it would have.

Also, mine is a Safari snorkel, and remember that the snorkel head has bits at the base of the head that allow water to flow out for when driving into heavy rain, a plastic bag won't seal that bit too well and hence why the engine probably won't stall.

The plastic bag is sucked hard around the top of the snorkel, with out doubt, but enough air still makes it way into the engine to run it.

The bag is definitely sealing. The ducting to the box is definitely sealing. It can only leave the air box lid ! or a least that is all that I can think of.

Originally Posted by Drover

The plastic bag is sucked hard around the top of the snorkel, with out doubt, but enough air still makes it way into the engine to run it.

The bag is definitely sealing. The ducting to the box is definitely sealing. It can only leave the air box lid ! or a least that is all that I can think of.

As mentioned above - were you doing these experiments with the (ram) snorkel head removed???

If you have some, try putting some vaseline or rubber grease on the air filter seal and see if that does the trick.

As mentioned about the ram.

Have you also closed of the drain hole in the bottom of the air filter box?

The airflow is via the base of the air box up through the filter and on to the engine. There's definitely at least one open drain hole and I'm not sure if the air box is a press fit or bolted to the front guard. The air filter box lid and top side of the filter stays incredibly clean I've found. In all honesty I find the amount of dust into the air box is incredibly minor after owning Disco's.

Btw - the plastic bag is a bad idea - better to use something solid which cannot be sucked in.

Have you considered air through the crankcase breather?

Just a thought

Drover did you ever complete your experiment?

If I disconnect the pipe going from the air box to the turbo and place a rubber mat over the end of the hose, whilst the engine is running, in order to seal it, the engine will stall within 5 seconds.

If I place the rubber mat over the top of the snorkle (with the ram head removed) the engine runs quite happily.

I have now completely uninstalled the Safari Snorkel, sealed the duckbill at the bottom of the air box, also sealed the drain plug that is inline in the ducting from the air box to the wing, reinstalled the Snorkel, sikaflexed all the joints (some where originally sealed by ARB, others where not at all !!!).

I waited for the sikaflex to cure and retested - no change, engine still runs happily with the top of the snorkel sealed.

So I have come to the same conclusion as you, the only place where air could now be getting into the system is the lid of the air box.

I came across this photo on the Discovery2 website, maybe that is the answer - add a strip of foam/rubber tape to the lid?