Wastegate and BOV
 

Help to understand the function of the element so my turbo that I am rebuilding. I ahve a Garrett turbo, dont know what T4, T25, T28? I assume the wastegate is attached to a rod and controled by some type of presssure accuator in that when the actuator gets more pressure than the spring, it begins to open. Now there is another valve attached to the side of the intake manifold that appears to dump excess intake pressure into the exhaust manifold. Is this like a BOV? It looks to be controled by vacume maybe? Is this maybe a overboost protection or surge?

Thanks for your help guys.

no BOV on a diesel


the valve on the intake is probably the EGR

The valve on the compressor is an ARV. Air Recirculation Valve. It's only reason for existence is to reduce the intake pressure under certain engine conditions for higher EGR (Exhaust) flowrate into the intake manifold.

The turbo you have is a Garrett (AirResearch) TA031, aka T3.

Thanks for helping the new kid! I'll keep lurking...

I dont think I have a ARV. Thats on the turbo itself on some models I think. There are two on the intake, one is the EGR valve. But there is another on the intake accross from it connected to a vacuum or pressure line that has a butterfly valve in the intake. What is the function of this valve?

It works as a throttle to restrict the airflow and force more EGR gasses into the intake manifold.

SO hypothetically, IF the EGR is gone there is not need for this part? What is it called?

Intake butterfly. With the EGR disabled, the ARV and butterfly are of no more use.