Abarth oil consumption
OK; so I think I'm at a point where I'm ready to share this now...
It's well known that Abarths like a good drink of oil and regularly so. It's also known that Fiat no longer produce the rocker cover breather valve, so it's not like you can replace the valve to help with this.
It's long been my feeling that the design seems to lead to the motor putting quite a bit of vacuum in to the rocker cover, which might be one source of oil consumption.
Fiat suggest that the Abarth is likely to use around 500ml per 1,000 miles driving; which pretty much matches up with my Abarth's drinking habits.
I have of course been considering ways to reduce the consumption and doing a fair bit of research before arriving at a possible conclusion and testing it out.
Blocking the breather up and venting to atmosphere was one option; however venting to atmosphere is no longer legal, hence the sealed system the cars have. It also risks filling the engine bay with oil vapor too, which could get dangerous and messy.
You could, therefore, fit an oil catch can. Personally I'm yet to be convinced these are efficient at what they do, so could still lead to venting fumes to atmosphere, plus there is also the risk that these add further resistance to the system and actually generate positive pressure in the crank case, which you don't want! Practically speaking there is also very limited room in the Abarth engine bay to appropriately install one of these. So it's probably a no-go.
That kind of leaves you trying to work with what you have and make the existing system more efficient. I figured it probably needs a bit of restriction added to the system to prevent too much vacuum across the crank.
I decided first to inspect the breather valve to see what sort of state this could possibly be in. It honestly didn't look so bad but I gave it a clean up anyway, but I was surprised at just how slack it felt, like it must be allowing a lot of gas passed it.
Figured this might be a good place to try and introduce a little bit of control and see what happens.
What I did was fitted a small rubber o-ring at the bottom of the valve, underneath the spring. I had a couple of spare MAP sensors from previous cars sat around, as you do, and the little green o-rings off them are the perfect size to fit in the valve body nicely.
It sits below the spring; so o-ring goes in, followed by spring, followed by the white plastic valve.
That should have the effect of narrowing the passage between the white plastic valve and the o-ring very slightly, which will form more of a restriction under greater vacuum and also has the effect of shortening the spring by a few mm, introducing a bit more resistance to movement by pre-loading the spring. Meaning the valve is more inclined to stay shut.
So I fitted this about 3 weeks ago now and have been quite busy with work and have done a lot of driving.
Initial results seem very positive. I would normally have expected to have to add oil with the amount of driving I've done, but so far oil levels don't seem to have moved far at all.
I've done no scientific measurements but have been keeping an eye on dip-stick and around the engine bay just in case I've caused a pressure lock somewhere but so far no ill effects have been identified.
Thought I'd share but remember, any modifications you do are done so at your own risk!
OK; so I think I'm at a point where I'm ready to share this now...
It's well known that Abarths like a good drink of oil and regularly so. It's also known that Fiat no longer produce the rocker cover breather valve, so it's not like you can replace the valve to help with this.
It's long been my feeling that the design seems to lead to the motor putting quite a bit of vacuum in to the rocker cover, which might be one source of oil consumption.
Fiat suggest that the Abarth is likely to use around 500ml per 1,000 miles driving; which pretty much matches up with my Abarth's drinking habits.
I have of course been considering ways to reduce the consumption and doing a fair bit of research before arriving at a possible conclusion and testing it out.
Blocking the breather up and venting to atmosphere was one option; however venting to atmosphere is no longer legal, hence the sealed system the cars have. It also risks filling the engine bay with oil vapor too, which could get dangerous and messy.
You could, therefore, fit an oil catch can. Personally I'm yet to be convinced these are efficient at what they do, so could still lead to venting fumes to atmosphere, plus there is also the risk that these add further resistance to the system and actually generate positive pressure in the crank case, which you don't want! Practically speaking there is also very limited room in the Abarth engine bay to appropriately install one of these. So it's probably a no-go.
That kind of leaves you trying to work with what you have and make the existing system more efficient. I figured it probably needs a bit of restriction added to the system to prevent too much vacuum across the crank.
I decided first to inspect the breather valve to see what sort of state this could possibly be in. It honestly didn't look so bad but I gave it a clean up anyway, but I was surprised at just how slack it felt, like it must be allowing a lot of gas passed it.
Figured this might be a good place to try and introduce a little bit of control and see what happens.
What I did was fitted a small rubber o-ring at the bottom of the valve, underneath the spring. I had a couple of spare MAP sensors from previous cars sat around, as you do, and the little green o-rings off them are the perfect size to fit in the valve body nicely.
It sits below the spring; so o-ring goes in, followed by spring, followed by the white plastic valve.
That should have the effect of narrowing the passage between the white plastic valve and the o-ring very slightly, which will form more of a restriction under greater vacuum and also has the effect of shortening the spring by a few mm, introducing a bit more resistance to movement by pre-loading the spring. Meaning the valve is more inclined to stay shut.
So I fitted this about 3 weeks ago now and have been quite busy with work and have done a lot of driving.
Initial results seem very positive. I would normally have expected to have to add oil with the amount of driving I've done, but so far oil levels don't seem to have moved far at all.
I've done no scientific measurements but have been keeping an eye on dip-stick and around the engine bay just in case I've caused a pressure lock somewhere but so far no ill effects have been identified.
Thought I'd share but remember, any modifications you do are done so at your own risk!