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RaRo 3.5 efi Breathers

It appears that the majority of my valley gaske leaks are down to blocked breathers. I've disconnected the rubber pipe which runs from the left side (viewed from the front) rocker cover to the front of the plenum chamber, and the oil leak has slowed from a flood to an occasional drip.

However, i think the blockage is not in the plastic filter thing screwed onto the rocker cover (new one fitted) or in the rubber pipe (can blow through) but is at the plenum.

The rubber pipe connects onto a metal tube on the plenum, about 10 mm diameter and about 30 mm long. If I connect the rubber tube to this pipe and suck, no air flows. I had assumed this pipe was drilled straight through into the plenum (up stream of the butterfly) but when I disconnect the air intake hose from the plenum (to the air flow meter), I can see no corresponding drilling inside the plenum.

So questions?

Should I be able to suck through the metal tube?

What does it connect to?

Any hints on unblocking it?

Also, the breather at the back of the right hand rocker cover looks odd. There is a part which looks like a drawing pin (ERC3933) which I think should have a plastic filter clipped over it? However, this also seems to be blocked, and I think I can see something metallic down the middle of the shaft which I think should be an airway. Is this a known or recognised bodge for something? Does the "drawing pin" unscrew from the rocker cover?

1986 3.5efi

Thanks

David

Reply to
rads
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On my '87 3.5 EFi, the breather system blocked in the plenum, blowing the valley gasket - I heard it go 'boing'!

The inlet into the plenum is DOWNSTREAM of the throttle plate - ie the engine side.

The passages are a 'dogleg' from where the breather tube connects to the plenum. If you look at the plenum, there will be two small 'core plug' type blanking plugs (at 90 deg. to each other) where the holes have been drilled in the plenum casting to create the dogleg. You need to prise these out and I used a twist drill of appropriate dia. to 'ream' out the accumulated crap. You can buy replacement plugs from your local parts emporium for peanuts (they may want real money, but it's worth trying with peanuts...sorry, crap joke)

BTW, I believe that on 3.9's they modified the plenum so that the CCV went straight into the 'hole' rather than use the 'dogleg' - less likely to block?

You are correct that the 'drawing pin' thing should have a foam filter/plastic clip on housing thing. And yes, there should be a small (2mm?) dia hole through it.

AFAIK, the 'drawing pin' is pressed into the rocker cover, and is not supposed to come out.

BTW, you will have to replace the valley gasket, 'cos the leask will only reduce, not stop when you've fixed the breather! Use the 'composite' replacement, not the original tin one.

Also, whilst you've got the intake manifold off, check the condition of the heater pipes that are bolted to the bottom of the manifold - they tend to rust, and if they're anything like mine, when you have the thing back together and try to reconnect the heater, they'll decide to collapse into rusty heaps. Grrr.

Good luck :)

Regards,

Horse

Reply to
horse

Thanks for the reply.

This sounds like a major PITA. The bodger in me feels tempted to "upgrade" my plenum to 3.9 spec. by drillind straight through the breather pipe into the air intake. Anyone strongly object?

David

Reply to
rads

Nope, the later 3.5's have the straight drilling anyway. Common mod (bodge?). Badger.

Reply to
Badger

Righty-ho, Black and Deckers at dawn it is. Thanks to horse, Badger and any other of our fluffy cousins I have missed for their input!

David

Reply to
rads

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