2005 Dodge Caravan-Only overheating on highway

ironman14

Hi, recently bought a 2005 Dodge Caravan 2.8 Diesel cargo edition (Ram Van) in the Netherlands. 245 K on it. Running around town it runs fine but driving 120km or more on the highway the temp runs up slowly to close to the red. when I slow down to 90 or 100km temp drops back but still over the mid position. Stop and go traffic is no problem, temp does not run up. Coolant level is as it should be, the reservoir looks rather rusty brown though. Looking for some advice on how to fix this..... need to make a few long distance trips soon! Thanks in advance for your comments!

thecardoc3

Overheating under a load like that is usually a coolant flow issue. You are going to have to find out whether the radiator or engine block has debris causing poor flow or if the impeller in the water pump has eroded away.

In some rare occasions there are cases where there is an airflow issue at higher speeds and that cannot be ruled out at this point but would be very unlikely with a Caravan unless someone has put something in between the AC condenser and the radiator.