Technical Newbie: Crankcase Breather Hose

[FIAT40]

Greetings…and my humble thank you for letting me into this Forum.

I am a new owner 1975 Spider 124…this is an awesome junkyard find and my favorite car of all time…everyone stops me to admire. Great patina too.

We have been sorting out all issues, starting with the engine, replaced the old carburetor and air filter with a new Weber…she runs mighty fine.

However, what to do about the leaking Crankcase Breather Hose…we capped it with a KN Filter and she still spews oil.

Any advice is welcome…I have heard about using a Catch Can, but don’t know best model, there are so many choices.

Reconnecting to the new Weber Carb doesn’t sound reasonable ?

Many thanks for your advice.

Dan

 

[bugsymike]

Greetings…and my humble thank you for letting me into this Forum.

I am a new owner 1975 Spider 124…this is an awesome junkyard find and my favorite car of all time…everyone stops me to admire. Great patina too.

We have been sorting out all issues, starting with the engine, replaced the old carburetor and air filter with a new Weber…she runs mighty fine.

However, what to do about the leaking Crankcase Breather Hose…we capped it with a KN Filter and she still spews oil.

Any advice is welcome…I have heard about using a Catch Can, but don’t know best model, there are so many choices.

Reconnecting to the new Weber Carb doesn’t sound reasonable ?

Many thanks for your advice.

Dan

Many people advocate catch cans, my thoughts are having worked on cars in the motor trade since 1969, they never needed them when they were new!
Hence I believe in many cases the problem is more to do with wear on pistons and cylinder bores causing excessive "blow by" so an easy check when engine is warmed up and idling, undo the oil filler cap then assuming the cam doesn't flick loads of oil in your face what you are checking is if you can feel fumes blowing out of the engine, often making a drumming noise and smelling of engine fumes.
If you have those symptoms in my opinion apart from checking that the engine breather isn't restricted the only re cure is a "good" engine rebuild so not cheap.
Having said that if you can do the work yourself and the engine isn't too badly worn, simply honing the cylinder bores and correctly fitting a good set of new piston rings may be all that is needed. Obviously new bearings and gaskets along with grinding in the valves, cambelt, etc. it doesn't have to cost a fortune, but does take a fair bit of time and attention to details.
Another small detail, engines have a correct running temperature, at that point pistons have expanded and form a better seal and the engine actually runs quieter. So I always make sure the thermostat works correctly (roughly 90 degrees Centigrade in centre of the gauge) if you only do short journeys oil quickly contaminates and builds up condensation causing more wear.

 

[s130]

You need to consider how the breather hose feed into the air filter housing. On most designs the breather for a downdraught carb enters the housing right next to the carb. inlet choke/venturi/barrel. The oil vapour is immediately sucked into into the carb and has no time to condensate. Unlike a diesel engine with dirty EGR soot petrol carbs remain very clean.

With this said on our Strada Abarth with sidedraught carbs there is a big airbox and the breather used to enter at the bottom some 4 inches below the 4 intakes and between the two middle ones. The oil vapour would condense on it's way to the carbs and collect in the boot of the airbox and over time seep out covering the front of the engine block in oil. Very messy.

I considered a catch can but in the end just routed a new breather hose down to below the engine. I get the odd drip of oil, far less than some engines leak oil.

If you engine has large amounts of "blow by" as mention by @bugsymike then "free venting" or "catching" may prove to be more of a challenge. Often engine performance and compression are not really affected by blow by as the excess oil forms a compression seal.

I would consider sticking with the orignal setup. Clean everything up and monitor. You may find that everyting is perfectly acceptible.

Lastly and importable check that the breather hose / path has a flame trap. This may need cleaning as they can gum up with emulsion but it is important to have one. On Fiats the flame trap is a wire spiral gause inserted into the breather hose or the tube to which the hose attaches.

 

[bugsymike]

As @s130 mentions "Lastly and importable check that the breather hose / path has a flame trap. This may need cleaning as they can gum up with emulsion but it is important to have one. On Fiats the flame trap is a wire spiral gause inserted into the breather hose or the tube to which the hose attaches."
In the mid 70s I worked at a Lada Dealership (Fiat 124 under licence) and in every service we used to clean out that spiral gauze filter/flame trap at the same time as replacing the air filter element, if filter dirty blocked it can encourage oil fumes to be sucked from the breather rather than fresh air.
In the late 60s emulsion was a common issue when adjusting the tappets the rocker covers were often full of "mayonaise" I suspect thick oils and colder engines largely aggravated it.
Engines run much hotter, efficiently and use thinner high quality oils these days so less of an problem if used regularly.
Many classics only do occasional longer trips so more likely to cause oil contamination issues.

 

[FIAT40]

This is truly a great group of FIAT enthusiasts- thank you for your comments…I will try all suggestions soon and report back.

I have owned many sports cars and the Spider absolutely gets the most interest from everyone, despite their age. I call it the Poor Man’s Ferrari

 

[s130]

I have owned many sports cars and the Spider absolutely gets the most interest from everyone, despite their age. I call it the Poor Man’s Ferrari

Then there is the Fiat Dino

Fiat Dino

or Lancia Thema 8.32

Lancia Thema 8.32