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Does a 3.9 V8 need any breathers


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Breathers to protect against water ingress when wading, that is.

Yes I know I mentioned wading and v8's but it can be done. I'm not planning anything fancy, but breathers are cheap and easy protection.

Are there any as standard ?

Is it worth adding any ?

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There's that little mushroom vent thing at the back of the left hand rocker cover - seems to be blocked as standard anyway, though. Can't think of anything else.
there's a breather on the back of the right hand rocker cover

Of course which of us is right depends on which way you're looking at the engine ;)

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Depends on the age of the engine and your definition... :huh:

The rockers can both have breathers (out) that go to the carbs to dispose of nasty gases and keep internal pressure as low as possible.

As already mentioned, the RH bank (looking from front) can have a little breather (in) at the back end. I've also seen fuel filter type setups on the other side as well though.

Then there can be the sneaky little one on the block at the back of the left hand bank, just below the valley gasket face. More often than not it has a blanking plug but sometimes it has a T piece that either has a filter on it or feeds back into the bottom of the air filter.


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carb v8 have an open engine breathing system. air is drawn into the block via a small tube at the rear of the even cyclinder back. other end is connected to the air box; I don't have hence the mini K&N at the back below:

Natrually you can raise the height of this and it is a good idea to have filtered air drawn in.

And as mentioned gases are drawn out of the engine via the rocker covers and connected to the carbs - there a small cylinders - flame traps plumbed in between.


I dunno how much of this remains with efi engines and that the crankcse breater is blocked off, hmmm.... dunno sabout that either.

notice the stainless steel clutch hose, and yes, those rockers are polished! (someone with dremel and too much time :)

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The mushroom thing has a tiny pinhole through it, god knows why. My vote would be remove & tap the hole for a raised breather pipe. A small fuel filter inline would prevent major debris from being sucked in.

The flame trap for the big breathing on the front rocker cover should breathe directly into the plenum anyway so naturally sealed.

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Andy - you could wrap the whole engine in a plastic bag and ask a nice man with a diesel to pull you through? Ive got a tow rope? :D

[tin hat now used as cricket box]

I thought that was only on ye oldy worldly carb engines the EFI plenum chamber collects all the breathers from the engine to be re-burned.

even the drain on the rear of the block.

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On the EFI there’s the flame trap with breathes straight back into the plenum …. so you can forget that. The mushroom on the rear of the left hand bank (odd numbered cylinders) should have a compressed foam filter with a plastic cap. That is breathing out ……… mine has been under water a few times with no issues……….. :blink:

Don’t forget to bung up the oil drains in the bottom of the dizzy (or extend with axle breather pipe) ……….although I would be surprised if the engine was still running in that depth of water ………. with careful planning and a LOT of luck, the dizzy will run submerged.

However, still beats the hell out of a stinkin 4 pot oil burning stove. :lol::lol::lol:


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