[Vwdiesel] Running a little hot, Radiator a little cool.

[Will Taygan]

I'm hoping this is straightforward.

Guessing a thermostat.  Anything else I'm missing?

1994 1.6TD FrankenJetta (gas to diesel conversion)

Jetta is running one tick hot, occasionally getting down to normal.

Radiator is warm, but cool enough to touch.

Standard flow out the little hose on the coolant reservoir.  No bubbles.

Aftermarket radiator has 3 years on it.

Can I assume the water pump is fine if I see good flow out the little
return hose on the coolant reservoir?

Anything else I'm missing?

Thanks,

Will in Alaska.