Technical 1.2 69 horse air filter housing breather attachment

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Technical 1.2 69 horse air filter housing breather attachment

Haddock123

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One of the first things I did upon purchase was some maintanance. And yes, when removing the air filter housing I broke off the small hose attachment on the end of the cranckcase breather hose receiver.
I’ll try to add some pics.

searched the forum, found this thread: https://www.fiatforum.com/threads/air-filter-change.464385/

and specially the post by @jrkitching that quotes: The 60HP engines have air filters that can be changed in about a minute, without tools. Later 69HP engines are not only secured by fiddly screws which are stupidly easy to cross thread, they also have a fragile breather attachment on the back of the airbox which will break in an instant if you are not careful.

my question is: this tiny hose is a breather, but from where?

I left the hose to breathe into the great wide open and blocked the hole in the plastic housing with a screw.
 

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The larger hose comes of the cam over and is the crankcase breather. This is way your throttle body is all oily and mucky.

The smaller hose (to the broken barb), comes from the bottom of the throttle body and is some sort of air bypass hose.
It bypasses the butterfly and idle control valve in the throttle body.

If you run your hand down the pipe, it just pushes on to the lower right side of the TB (right side as you stand in front of the car).

As you have found the barb under the airbox is very brittle, a bit too late for you now but when taking the airbox off, reach around and pull the end off the TB first before doing anything else.

I've broken one in the past.
I just bunged up the hole and used a longer pipe and fed it into the air intake trumpet.
 
The smaller hose (to the broken barb), comes from the bottom of the throttle body
Correct
It bypasses the butterfly and idle control valve in the throttle body.
no idle control valve on the 1.2 The pipe just moves the crankcase gasses from above the throttle body to below via engine vacuum when the butterfly is almost closed

When they get blocked or the vacuum isn’t correct you get all sorts of trouble with oil on the MAP sensor

Here’s mine blocked being cleaned


And Fiats view

  • with small throttle openings (and, in particular, with the engine idling or in deceleration conditions) the gases are drawn in downstream of the throttle
E24988BD-4D6A-4AB8-BC9F-C468B2722CFB.jpeg
 
This now means I’ve got to block the small hose. It will take in unfiltered air.
In the long run no problem. I will redirect the breather hose via a catch can and filter.
 
If you are going to vent to atmosphere, yes you can just plumb the crankcase breather in to that and block off everything else.

But if you are routing the crankcase breather through a can and back into the air intake via the airbox, you are going to have to work out how to bypass the crank gases to under the throttle body after the can as there will be no escape for crank gases when you close the throttle.

You would be best sticking a T piece joiner into the return from the can to the airbox and run a small pipe from that to the bypass port under the throttle body.

You'd have to measure the ID of all the pipes to get the right size, but something like this.

You could also use this as a cheap fix for the broken barb (cheaper than a new airbox).
Splice the T piece into the larger breather pipe that is already there from the cam cover to under the airbox.
Then use the smaller T to connect to the smaller bypass port under the throttle body.
Then just block up the hole left by the broken barb under the airbox.

This is pretty much the same set up as the 60hp system.
The crank breather hose has the smaller bypass pipe branching off it like this.
 
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Looking at you original photos

photo one it looks like the LHD is a slightly different design to mine. Not that it makes any difference to our answers. Might just be a year change though

Photo one there appears to be some build up of gunk on the edge of the butterfly valve. This will be adjusted for electronically. The throttle closed angle will not be where it normally would be. When it gets too far out it will start to affect the cars running

Photo two. Looks like an easy repair. As per @The Panda Nut

I’d use original slow cure JB weld just because I happen to have some. The part stuck in the tube should pull out with a large self tapping screw


In my opinion it would be best to keep the pipe as Fiat intended.
 
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