I have what appears to be oily film in coolant reservoir in Holden (Chevy) Cruze 2010 automatic

Question

Car runs fine for 30 mins in driveway with no overheating but does overheat when driving upwards of 80kph sometimes. Not game to drive it much as if it is not the head gasket, then driving and overheating etc could lead to it blowing.

Have recently had water pump replaced following visible leak under car and this appeared to help but following a drive on a hot day, the car overheated again and coolant level went down.

I have also changed the coil pack and spark plus and also drained and refilled transmission as I was having other issue with the Cruze (lemon)!

There does not appear to be any coolant in the oil which is clear and level remains the same.

Have previously noted the crumpling of the large radiator hose, which goes back to normal once cool.

Mechanic said that it could be oil cooler/thermostat etc. A second mechanic said that the head gasket is blown, although no bubbling of coolant and no white smoke or sweet smell from exhaust!

Any thoughts? Head gasket or other likely causes. Any help much appreciated.

Answer 1

HandyHowie is spot on here ... you need to change out the collapsing radiator hose as the first step to solving your issue. Your symptoms point to this as being the reason for it overheating at speed. This, however, will only be a "first step", because more than likely you are going to find more issues with it.

When the coolant heats up the coolant hoses also heat up, which makes them more pliable. When the system is flowing (after the thermostat opens), the coolant pump can cause enough suction to collapse the hose which is feeding it if the hose does not have the integrity (firmness) to stay normal. When the hose collapses, the coolant flow is GREATLY reduced which causes the engine to overheat. Once the engine is back to normal speeds, the hose will un-collapse, allowing proper coolant flow again, cooling the engine as it's supposed to.

Changing the collapsing hose out with a new one should solve that issue, but like I said, you'll most likely find other issues due to the overheating in the first place.