Missing oil Mystery
Discussion
When a conventional engine is not running, the majority of the oil will be contained in the sump below the crankshaft.
What is the comparable situation with the V8 Vantage engine? Presumably there is not much space at the bottom of the engine for oil to rest. We are familiar with the stainless steel tank containing the dipstick, but is there another bigger oil tank somewhere?
Jon39 said:
When a conventional engine is not running, the majority of the oil will be contained in the sump below the crankshaft.
What is the comparable situation with the V8 Vantage engine? Presumably there is not much space at the bottom of the engine for oil to rest. We are familiar with the stainless steel tank containing the dipstick, but is there another bigger oil tank somewhere?
This is the oil tank removed from the car....probably holds around 8 litres or so... The remaining oil would be in the engine, pipes, oil cooler and the shallow sump.What is the comparable situation with the V8 Vantage engine? Presumably there is not much space at the bottom of the engine for oil to rest. We are familiar with the stainless steel tank containing the dipstick, but is there another bigger oil tank somewhere?
Thank you Quinny.
I can see now that the header tank, which is clearly visible under the bonnet, is just the top part of a much bigger tank.
There presumably is a valve of some sort, which only allows oil in the header tank to drain downwards very slowly (ie. it seems to take about a month for the header tank to empty if the car remains unused).
Jon39 said:
Thank you Quinny.
I can see now that the header tank, which is clearly visible under the bonnet, is just the top part of a much bigger tank.
There presumably is a valve of some sort, which only allows oil in the header tank to drain downwards very slowly (ie. it seems to take about a month for the header tank to empty if the car remains unused).
I don't think the tank empties itself, even after long periods of layup, it just goes lower than the bottom of the dipstick..I can see now that the header tank, which is clearly visible under the bonnet, is just the top part of a much bigger tank.
There presumably is a valve of some sort, which only allows oil in the header tank to drain downwards very slowly (ie. it seems to take about a month for the header tank to empty if the car remains unused).
The rest of the oil is in the engine galleries and the sump
The V8 is not a true dry sump system
My understanding is because the engine is so low a normal sump would not fit
So it has a shallows sump, the header tank and a recirc system
That's why the dipstick is in the header tank and the engine needs to be run to confirm the correct reading
The V8 is not a true dry sump system
My understanding is because the engine is so low a normal sump would not fit
So it has a shallows sump, the header tank and a recirc system
That's why the dipstick is in the header tank and the engine needs to be run to confirm the correct reading
DAMIT said:
But doesn't running the engine actually lower the level on the dipstick? So if no oil shows before running
Don't over think it.....there's over 10 litres of oil in the system, the AMV8 isn't known for using loads of oil.... Unless there is something seriously wrong, so even the most inattentive mechanical numpty would notice it, there is little chance of that engine, ever NOT having enough oil to keep it adequately lubricated..... The most I ever put in mine between services was a measly 250cc or so....and even that wasn't needed, it was just that I prefered to see the level at the top mark than just below it...
Quinny said:
DAMIT said:
But doesn't running the engine actually lower the level on the dipstick? So if no oil shows before running
Don't over think it.....there's over 10 litres of oil in the system, the AMV8 isn't known for using loads of oil.... Unless there is something seriously wrong, so even the most inattentive mechanical numpty would notice it, there is little chance of that engine, ever NOT having enough oil to keep it adequately lubricated..... The most I ever put in mine between services was a measly 250cc or so....and even that wasn't needed, it was just that I prefered to see the level at the top mark than just below it...
Jon39 said:
Thank you Quinny.
I can see now that the header tank, which is clearly visible under the bonnet, is just the top part of a much bigger tank.
There presumably is a valve of some sort, which only allows oil in the header tank to drain downwards very slowly (ie. it seems to take about a month for the header tank to empty if the car remains unused).
There is no check valve, since the bottom of the tank feeds the pressure side of the engine oil pump. The tank drains slowly over time, not because of any leaky check valve, but simply by passing through the clearances of the pressure pump as a result of gravity. The oil pools at the bottom of the engine 'dry' sump and slowly rises over time. I can see now that the header tank, which is clearly visible under the bonnet, is just the top part of a much bigger tank.
There presumably is a valve of some sort, which only allows oil in the header tank to drain downwards very slowly (ie. it seems to take about a month for the header tank to empty if the car remains unused).
Since the amount of oil that drains from the tank varies with time, there cannot be an accurate measurement with the dip stick unless the system is 'reset', which means starting the motor and letting the scavenge elements of the oil pump suck dry the oil pan and pump the oil back into the top of the oil tank.
You wait a few minutes, then check the oil level, which has had time to settle, but not long enough for it to begin its inexorable drain to the engine sump.
J12KJR said:
I think we are both saying the same thing but in different ways.
With regard to the Porsche system the TVR Speed Six is exactly the same and as you say on the basis you aren't going to run your car with low oillevel shouldn't be a problem unless you slipped in the oil pool when entering the garage.
As with the AM system you have to check from cold I just tend to do this every few hundred miles or before a decent run out/hoon.
We are saying the same thing With regard to the Porsche system the TVR Speed Six is exactly the same and as you say on the basis you aren't going to run your car with low oillevel shouldn't be a problem unless you slipped in the oil pool when entering the garage.
As with the AM system you have to check from cold I just tend to do this every few hundred miles or before a decent run out/hoon.
Steve, very nice explanation.
Quinny, you may well be right about not "needing" to check the level on the V8V, but some 12 cylinder owners have learned the hard way that even with a large capacity (wet) sump, it can get too low and BAD things can happen. Yes, different engine and lube systems (and perhaps early "short" dipsticks), and the 12s seem to use more oil than the eights, but worth noting.
Mikey, I think the V8's "dry sump" is as close to a true dry sump as can be found on a road car. Quite willing to be shown I'm wrong, though.
Errrr.... I don't think I ever recommended that owners don't "need" to check their oil levels
In fact I did the "how to" check your oil video, to encourage owners whom may not be that confident to have a go....
The point I'm trying to make is, don't panic, if you get a spurious reading... As the chances of there being a real problem are slim..
In fact I did the "how to" check your oil video, to encourage owners whom may not be that confident to have a go....
The point I'm trying to make is, don't panic, if you get a spurious reading... As the chances of there being a real problem are slim..
Quinny said:
My view on the Aston lube system is that, it holds around 10 litres of oil... This is more than twice what an average car with a sump would carry.
So unless there's a massive pool of oil, or some sort of catastrophic engine failure that means it's burning it at an excessive rate, which even the most inattentive owner would notice, there should always be enough oil to in the tank to provide adequate lubrication...
Didn't mean to misinterpret you, but barring the big pool of oil on the floor or huge clouds of blue smoke, I thought this could be interpreted as "no real need to worry about it" rather than "don't panic." That's why I put "need" in quotes. Point now clear So unless there's a massive pool of oil, or some sort of catastrophic engine failure that means it's burning it at an excessive rate, which even the most inattentive owner would notice, there should always be enough oil to in the tank to provide adequate lubrication...
DB9VolanteDriver said:
There is no check valve, since the bottom of the tank feeds the pressure side of the engine oil pump. The tank drains slowly over time, not because of any leaky check valve, but simply by passing through the clearances of the pressure pump as a result of gravity. The oil pools at the bottom of the engine 'dry' sump and slowly rises over time.
Since the amount of oil that drains from the tank varies with time, there cannot be an accurate measurement with the dip stick unless the system is 'reset', which means starting the motor and letting the scavenge elements of the oil pump suck dry the oil pan and pump the oil back into the top of the oil tank.
You wait a few minutes, then check the oil level, which has had time to settle, but not long enough for it to begin its inexorable drain to the engine sump.
Thanks for that. A clear explanation. It's what I thought but just couldn't get my head round the DRY sump bit.Since the amount of oil that drains from the tank varies with time, there cannot be an accurate measurement with the dip stick unless the system is 'reset', which means starting the motor and letting the scavenge elements of the oil pump suck dry the oil pan and pump the oil back into the top of the oil tank.
You wait a few minutes, then check the oil level, which has had time to settle, but not long enough for it to begin its inexorable drain to the engine sump.
Quinny said:
Errrr.... I don't think I ever recommended that owners don't "need" to check their oil levels
In fact I did the "how to" check your oil video, to encourage owners whom may not be that confident to have a go....
The point I'm trying to make is, don't panic, if you get a spurious reading... As the chances of there being a real problem are slim..
Why not post the video again for the new owners. Picture is worth a thousand words and all that !!!!In fact I did the "how to" check your oil video, to encourage owners whom may not be that confident to have a go....
The point I'm trying to make is, don't panic, if you get a spurious reading... As the chances of there being a real problem are slim..
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