Engine overheating

Hi eagle ed,

You need to check for a faulty fan relay or open in its wiring circuit.

You have a problem within the engine management system pull the code/s from the computer and comeback with it this is where we start. Also check the thermostat

Now it won't start. It turns but doesn't start.

Get a starting fluid/ether/better off gas in a spray bottle and spray into the carb or the throttle body on an EFI. Did it start and die? If not disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, distributor pick-up coil, ignition control module, ECM, Ignitor cam and crank sensors- Note: If it doesn't apply disregard it

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems with compression and valves opening and closing at the wrong time/broken or jumped timing belt/chain

Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following: Thermostat, Pressure test the Rad. Cap, Clogged radiator, Fan clutch, Radiator electrical fan, collaspe hoses, water pump.

Hi lj8451,

Does the fans operate when the temp increases?

The radiator fan sensor is faulty if they don't work

Hi lj8451,

If the fans are working continuosly when overheating, the radiator might be clogged or water pump is weak.

Turning on heater reduces the temp, so I guess a clogged radiator is more likely as the blower from the heater is helping to cool the system.

Hi bignick126,

Get a pressure test done to locate the leak.

Ensure the surfaces are clean and old gasket had been scraped off failing which the new gasket is not going to be seated evenly.

HI there,

If the system tests ok for external leaks, its time to get a head check done to check for a head gasket problem, most work shops can do this test, it is a chemical test that detects exhaust gasses in the cooling system, get this done next.

Mark (mhpautos)