JX td engine diverter valve.

[escovedo]

Does anyone know if the JX td engine diverter/blow off valve
is necessary on these engines.

[davidoft1]

I imagine that’s why it was designed and installed

[escovedo]

I imagine that’s why it was designed and installed

How strange, it seems to have been deleted
on the later td engines.

[ZsZ]

All early VW diesels had them and as you say, it was ditched from later ones.
Either it was for some security element for rare occasions, or for emission reasons. It releases the boost when you suddenly let.off the pedal after full throttle.
1.9 TD injection pumps had a damper on the throttle lever so boost spike could not happen if you quickly let off the pedal.
I ran my 1.9 mTDI without it for around 15 years without pronlems