Thermal intake gasket?

[AdamB]

its idle control based on coolant temp. the stat controls the amount of air the idle control valve passes as it pulses

Thought it was something to do with the idle control valve, thanks mate

 

[Texx]

the stat controls the amount of air the idle control valve passes as it pulses

The wax stat is separate to the idle control valve. A cold fast idle is only required for the first few minutes after the engine has been started, the wax stat provides the additional air required for this fast idle which allows the idle control valve to flow less air and be more accurate in how it controls normal warm engine idle.

Basically there is a small air orifice just in front of the inlet to the throttle plate, this feeds down into the base of the throttle body to supply air to the wax stat, the air flows through the wax stat back up into the throttle body to the manifold side of the throttle plate. When the coolant temperature is cold the wax stat is open allowing additional air to bypass the throttle plate, as the engine coolant warms up the wax stat closes and blocks off this additional air.

 

[dac69er]

The stat has an air pipe off it that goes to the pipe that runs round the back of the manifold to the idle control valve does it not? Does the stat not then regulate the amount of air that the idle control valve is supplied with when its cold?

 

[Texx]

The stat has an air pipe off it that goes to the pipe that runs round the back of the manifold to the idle control valve does it not? Does the stat not then regulate the amount of air that the idle control valve is supplied with when its cold?

The hose that runs to the air manifold that feeds various valves including the idle control valve, is fed via the same orifice that feeds the wax stat, the outlet of the wax stat feeds straight to the other side of the throttle plate. I've got a throttle body stripped down, give me 5 minutes and I'll get some photos.

 

[Texx]

 

[Tim@TBDevelopments]

thanks texx thats a good bit of information thankyou, learning all the time

the 3sgte ones just have it going in and out with no extra thermostat or anything

Tim

 

[Texx]

I'm not so sure how the later 3S-GTE with speed density works, but the earlier 3S (Rev1 & 2 SW20) have an additional cold start fuel injector and an idle-up VSV do they not? That would in affect do the same job as the wax stat on the 4E only the 3S ECU would control the additional fuel through the cold start injector whereas the 4E ECU adds cold start fuel enrichment compensation to the injection duration of the regular fuel injectors.

 

[Tim@TBDevelopments]

yes thats correct. its all ecu controller on the 3sgte all versions and models. Only difference is the earlier rev 1+2 has a cold start injector in place where the later just had enrichment done through the normal 4 injectors. All had idle controlled with a throttle body mounted idle control valve, but no wax system just a basic solenoid again ecu control.

there is another Idle-up vsv valve on all models but this is for the aircon system

Tim

 

[AdamB]

Texx, from those pics, if you were to block off the coolant connections to the throttle body, would that then make the idle control valve redundant since the outlet from the wax stat to the icv would always be closed since it would never get hot enough to open?

 

[Texx]

The idle control valve will get air from the throttle body regardless as to whether the coolant lines are connected or not, it's not affected by the position of the stat. The wax stat is naturally open allowing air to bypass the throttle plate and enter the inlet manifold. As the coolant temperature increases the heat expands the wax in the stat closing the valve and blocking off the air passage between the wax stat and inlet manifold side of the throttle plate.

If you were to remove the coolant feed to the throttle body the idle control valve would still do it's job, however the engine would also have a high idle due to the wax stat bleeding air past the throttle plate and into the inlet manifold. The idle control valve does not specifically need to take it's air feed from the throttle body, it just requires air that has passed through an air filter (as the air is going to enter the inlet manifold). You could simply remove that air hose from the throttle body and attach a small air filter to the end of it and the idle control valve will still function perfectly well.

If you want to remove the coolant feed to the throttle body and retain a normal idle control system, the obvious answer is to remove the throttle body from the inlet manifold, remove the wax stat from the throttle body, fill the area shaded in red (below photo) with some 2 part epoxy resin (Araldite, JB Weld, Super Steel etc...), apply a thin line of liquid gasket to where the blue line is (below photo), reinstall the wax stat to the throttle body, reinstall the throttle body to the inlet manifold (a new gasket would be a good idea) and reconnect the air feed to the idle control valve as normal.

The only problem I see with doing this is that the engine may suffer some idle/stalling issues during the first few minutes of a cold start(maybe 5°C and below). However this wouldn't be much of a problem if the car isn't a daily driver that's used most days of the year.

 

[AdamB]

Thanks for that Texx! Makes perfect sense now. I wasn't sure if the wax stat would always be open or closed if the heated coolant was removed.

 

[rid1ridz14]

Here is a gasket I made from oil resistant paper(made for gasket) for the waxstat. It’s not perfect but it does the job.

 

[SKINY]

Reminds me of corn flake box in the field for the scramblers kinda fix proper stuff will last a brave while

 

[gorganl2000]

as an alternative, i recall using silicone gasket maker ages ago...just make sure both surfaces are clean

PS - only a modest amount of silicone is required,,,i.e. do not paste on excessive amounts

 

[rid1ridz14]

my waxstat works, put in a boiling water and I can see the pin moving (opening and closing)
but still idle is not so well