When traveling at high speeds you have the best of all engine cooling conditions; a high flow rate of coolant through your system and a high rate of cool air passing over your heat exchanger.
Occasionally we have an inquiry from someone who describes overheating at high speed conditions. We walk through the possible causes:
- Is the temperature reading confirmed in multiple way to rule out a gauge failure
- Is the return hose or suction has not collapsed due to greater draw at higher rpm choking flow?
- Is the flow restriction caused by too few or too small a tube
- Is the radiator core clogged with sediment or lined with scale which impedes heat exchange
- Is the water passage in the jacket blocked
- Is the pump impeller cavitating
- Are there any obstacles to the air flow in front of the radiator?
- Grill opening, winches and jacks etc.
- External transmission coolers
- Turbo air charger
- Air conditioner condensers
- Pusher fan
- Is the fan shroud depth permitting air to escape
- Is the impeller intact and secure on the shaft?
- Is air exiting the engine compartment?
- Is the radiator surface area and face area adequate for the engine demands?
- Is the thermostat functioning or stuck or restricted?
If we can rule these out then we would suggest they look at the engine and why its generating the excessive heat.