lol better off with a ford its not my van its my brothers (my van is the old 5cylinder type ) and yea compression test I recon would be a good way not sure if hes tried that , checked for air locks and alls fine , the heater blows really warm , not sure but I think he has changed the thermostat too , just thought I would see if anyone on here had came across it with this van as a guy from Mercedes said he has never seen a problem like this on one of these vans