Spyder 4G64 Overheating Issue

[Clawless]

Hey guys,

I realized a little too late that I was empty, and I mean EMPTY, on coolant on a drive back from work. I really don't know how it was empty because I ended up changing hoses and doing a flush in June.

Noticed the temp gauge about 3/4 of the way full so I pull over to check. In the moment, my mind didn't think of a logical solution like buying coolant and just filling it up before the situation got worse so I do a very dumb thing. I was in a rush to get home (1.5-2 hr drive) and I drive with the heat on blast and making sure I let the car cool down if it ever got past 3/4 on the temp gauge.

I make it home, let the car cool down until nighttime, add coolant and bleed it. There are no visible leaks, no air bubbles after bleeding, and the temp gauge is normal when idling. I drove it the last two days and the gauge still says its overheating (3/4 to Max line).

I don't think its a head gasket, there's no smoke out the back or anything obvious to me. My best guess was driving it with no coolant messed up the coolant temp sensor or even the thermostat but I won't be able to verify until the weekend.

Any advice, please and thank you!

 

[waltah]

Isn't the 4g64 one of those that can develop an air pocket and overheat if not bled properly when filled? Ah yes ...

Fill the radiator and overflow tank. Warm the engine at idle until the thermostat opens (top of radiator gets warm) then race the engine to 3000 RPM three times. Let the engine cool, remove the radiator cap, and check that the radiator is full. If it's not, repeat the whole process.

Hope this is your whole problem!

Now that's a 4g64 in an Expo LRV -- not guaranteed to be the same as that engine in an Eclipse Spyder but I don't have that manual.

Many but not all Eclipses have a warning light for low water in the overflow reservoir. That light can keep you from ever having to deal with a low radiator water situation and I was surprised to find that not all our cars got them.

Time was, checking the radiator was a regular thing. But with coolant recovery systems, glycol antifreezes that don't boil away (yeah, I'm old enough to have used alcohol antifreeze ...) and now with extended life coolants nobody much does it. That yellow light is useful.

There's a magnet in a float in the overflow tank, it operates a reed switch in there when the float gets low enough. Once it's low the float may stick down when you refill and leave the light on. Smack the reservoir with your palm to get it loose so the light goes off.

 

[DSMPT]

Make sure the radiator fan turns on as it should and the thermostat is smoothly functioning.
If it's burning that much coolant due to a blown head gasket, you may be able to see it at tail pipe, and you can probably see the coolant on piston top if you remove spark plugs after the engine gets cold. You should check it, too.

 

[randman2011]

Ensure that your thermostat still functions properly. Usually when they get stuck they get stuck OPEN, but perhaps it can't open all the way now. If you've got a way to log engine data, check that the ECU coolant temp value matches the gauge's 3/4 indication, because those sensors can get damaged by high heat. I know this from experience.

 

[Clawless]

Thanks everyone for all the replies! I believe the issue is the thermostat. I let the car get hot and noticed that the upper radiator hose was hot while the lower hose was cold. Going to swap out the thermostat this weekend.