Not cooling,has new impeller and thermostate - Cars & Trucks

Steve, there's many causes of overheating. You say you have a new water pump and thermostat, so it's obviously not those at fault.

Just a question ... you say your car is not cooling, but is it actually overheating? A faulty temperature sender unit (it screws into the engine block, usually..) can give an incorrect reading on your gauge.

If it is overheating - steam/you can feel the excess heat - is your radiator fan kicking in? Is your car overheating as soon as you drive it? Or overheating when stuck in traffic .. and the fan isn't kicking in..?

Other things that cause overheating which spring to mind include a blocked radiator and/or a collapsed radiator hose.

Hot coolant enters your radiator via the TOP hose and cools as it goes down the radiator, then back into the engine via the bottom hose. Check both top and bottom hose after the engine has warmed - sometimes a hose can become 'flat' and blocked.

Another thing that causes overheating is a burnt head gasket/cylinder head problem.

Switch the engine on and look at your coolant bottle - a continuous 'bubbling' indicates that exhaust gases are finding their way (via a burnt head gasket) into the cooling system.

Any oil in the coolant bottle also indicates cylinder head problems. Also check the oil dipstick. If coolant (because of a defective head gasket/head) has found its way into the oil system the oil on your dipstick may appear a creamy/greyish sludge.