the reason it was 3 bar on restart is because it had only been running a few minutes between ons and offs and didn't get warmed up.

If it's the guage, that means the cluster has to be replaced. I've seen the back side of that guage at the junk yard and it's part of the whole thing.

That sending unit is in a tight spot and not much room to swing a wrench. I'm thinking of putting a "t" in there and adding a real pressure gauge so I wont panic at 70 mph when this thing shows 0 bar.