i have a 1999 VW Jetta GL 2.0. When im driving on the highway and doing about 110KM/Hr in 5th gear the RPM is at 3000, that seems too high! And also what I have noticed is that the engine cools down, the gauge for the engine where it shows if the car is warm or cold, drops significantly when on the highway! Please help me understand why this is happening? Thank you.
There's nothing you can do about the RPMs if it is a standard transmission... the gear ratios in the transmission & Differential determine
engine rpm. Keep in mind that this is a 4 cylinder engine, so they are geared for higher rpm as opposed to a V6 or 8 cylinder engine
that has more grunt (so to speak).
The Temperature drops because of a faulty Coolant Thermostat... I have a video on how to replace the thermostat. It is from a 1.8T
New Beetle, but the location of your Thermostat & removal steps are the same.