Scv Valves

[rambler]

Hi folks

Yes......i know,another scv valve question..........

When i had mine renewed recently (after they failed on me on the A1) ,i asked to keep the old ones.

Looking at them,i cant see any moving parts at all ( do they go in & out like a piston,or turn at all...), or is it all done electronicaly?

Can they be stripped down ?,as most here say,they still look almost new

Why do they 'stick ',as i cant find any moving parts ?

Be good to find out

[anchorman]

There are moving parts rambs, they are just not easy to see what moves and what doesn't. Electrical signals to the plugs open a plunger inside which regulates the fuel flow.

[igormus]

Hi folks

Yes......i know,another scv valve question..........

When i had mine renewed recently (after they failed on me on the A1) ,i asked to keep the old ones.

Looking at them,i cant see any moving parts at all ( do they go in & out like a piston,or turn at all...), or is it all done electronicaly?

Can they be stripped down ?,as most here say,they still look almost new

Why do they 'stick ',as i cant find any moving parts ?

Be good to find out

hi mate

the main meanings of the SCV are:

- admit diesel to be sucked into the pump;

- cut off diesel to stop the engine.

Each one is fed by 12V when turned the key in ON position -- > each SCV has been designed as normally closed valve --> this means when mounted this valve closes respective seat under ---> once your key is in ON -- the 12V signal excites solenoid coil and the SCV stem is being lifted up enabling diesel to be sucked and furthermore starting the engine. When you need to stop the engine -- it is understood you turn the key in OFF position -- this means 12V signal is removed from solenoid and the return spring inside returns the stem down closing suction hole and the engine stops.

The main issue with SCVs is burning out of their solenoid coils when the valve stem either plays or just cut off diesel. Thats is why it is necessary to check with that coil resistance to be sure all wings are in order and can create lifting force for valve stem. The electricity leak on the SCV body is other issue that is an equivalent to possible coil burning out. Cheers/Igor

[Big Kev]

Hi folks

Yes......i know,another scv valve question..........

When i had mine renewed recently (after they failed on me on the A1) ,i asked to keep the old ones.

Looking at them,i cant see any moving parts at all ( do they go in & out like a piston,or turn at all...), or is it all done electronicaly?

Can they be stripped down ?,as most here say,they still look almost new

Why do they 'stick ',as i cant find any moving parts ?

Be good to find out

hi mate

the main meanings of the SCV are:

- admit diesel to be sucked into the pump;

- cut off diesel to stop the engine.

Each one is fed by 12V when turned the key in ON position -- > each SCV has been designed as normally closed valve --> this means when mounted this valve closes respective seat under ---> once your key is in ON -- the 12V signal excites solenoid coil and the SCV stem is being lifted up enabling diesel to be sucked and furthermore starting the engine. When you need to stop the engine -- it is understood you turn the key in OFF position -- this means 12V signal is removed from solenoid and the return spring inside returns the stem down closing suction hole and the engine stops.

The main issue with SCVs is burning out of their solenoid coils when the valve stem either plays or just cut off diesel. Thats is why it is necessary to check with that coil resistance to be sure all wings are in order and can create lifting force for valve stem. The electricity leak on the SCV body is other issue that is an equivalent to possible coil burning out. Cheers/Igor

Once again, Big Chap....superb explanation and educational for us learners. Thanks.

Big Kev

[Jamesbelfast]

Denso refer to these as Surge Control Valves. They are simple solenoid motor operated devices a bit unlike the older stop solenoids fitted to ancient diesel engines. They work a bit more subtly though and instead of just permitting or stopping fuel flow they can actually vary the flow depending on engine demand. They not only control how much fuel the pump can suck in but also regulate the maximum pressure the pump is allowed to deliver. As both these aspects can vary quite quickly it is possible the control meachanism can begin to surge - that's why Denso refer to them as Surge Control Valves.

[rambler]

Hi folks

Yes......i know,another scv valve question..........

When i had mine renewed recently (after they failed on me on the A1) ,i asked to keep the old ones.

Looking at them,i cant see any moving parts at all ( do they go in & out like a piston,or turn at all...), or is it all done electronicaly?

Can they be stripped down ?,as most here say,they still look almost new

Why do they 'stick ',as i cant find any moving parts ?

Be good to find out

hi mate

the main meanings of the SCV are:

- admit diesel to be sucked into the pump;

- cut off diesel to stop the engine.

Each one is fed by 12V when turned the key in ON position -- > each SCV has been designed as normally closed valve --> this means when mounted this valve closes respective seat under ---> once your key is in ON -- the 12V signal excites solenoid coil and the SCV stem is being lifted up enabling diesel to be sucked and furthermore starting the engine. When you need to stop the engine -- it is understood you turn the key in OFF position -- this means 12V signal is removed from solenoid and the return spring inside returns the stem down closing suction hole and the engine stops.

The main issue with SCVs is burning out of their solenoid coils when the valve stem either plays or just cut off diesel. Thats is why it is necessary to check with that coil resistance to be sure all wings are in order and can create lifting force for valve stem. The electricity leak on the SCV body is other issue that is an equivalent to possible coil burning out. Cheers/Igor

Ah........A kind of solenoid valve...... can only be opened via electronic current / pulse ,very similar to set up used in gas valves in most boilers in this country,a thermocouple sends a small electrical pulse generated by the pilot light just inside the sight glass,the electrical pulse activates the magnet and holds the solenoid valve open....thus gas goes through it.

My city & guilds in plumbing & heating ,knew it would come in handy one day

When fuel is lost ( gas or electric) the valve closes,thus the engine / boiler wont fire up.

Cheers Igor / Anchorman