Our 2000 Civic recently started overheating. I took it into Firestone who replaced the thermostat, radiator cap, temperature sensor and something else I can't recall (it was a plug that went in near the thermostat I think it was the fan switch not 100% though). They also flushed out the radiator/system. Then they told me it appeared to be a cracked head gasket.

I took it to another mechanic who replaced the head gasket for me. (Firestone wouldn't do it because I have 150k miles on it)

My radiator is only a year and a half old, my water pump is only about a year old.

It is still overheating. When around town at lower speeds it takes a long time (2-3 hours) to actually overheat, though having the air conditioner on can speed this up to an hour and a half to two hours.

On the interstate (speeds 65mph and up) it overheats much quicker. The fan doesn't kick on until it is close to 3/4 of the way up. It stays on only briefly (5-10 seconds) and turns off again.

If when the heat goes up I turn the heater on the car cools down very very quickly. (back to normal within 15-25 seconds).

I'm thinking at this point the issue lies within the fan but I'm not sure what exactly to have replaced or worked on. Any help would be appreciated.

 

At highway speed, the fan doesn't matter much. You get plenty of air forced through the radiator by the motion of the car. In order to make the fan run all the time, unplug the fan switch on the thermostat housing and jumper the pins in the plug on the car side. The fan should now start immediately when you turn the key on. Test drive like that and see if it helps any.

Most likely it's still the head gasket, your new one could have blown again. Park on level ground (or facing uphill, so the radiator is the highest point). Wait until the engine is cold then take the radiator cap off. The radiator should be full to the top. If it isn't, that's a problem, add coolant to fill it. Then start the engine (cold) with the cap off and rev it. If bubbles of air and/or coolant blow out of the radiator, the head gasket is bad.

 

Eww...I hope not. I'll be pretty mad if a head gasket I had replaced next week blew already. I'll try out the test you gave tomorrow though and see what happens.

 

I just did what you said.

Coolant was up to the top. When I reved it, no bubbles appears and it didn't blow out. It just kinda "overflowed" the level raised and some of the antifreeze ran out.

 

What is wrong with this picture? It looks to me like Firestone folks threw everything they had at the problem without first checking to see what the real problem was. There's NO way that all of those things were bad and since none of them were bad, you should NOT have to pay for them. Threaten them with small claims court if you have to, but don't let them get away with charging you for that stuff.

Is this how ASE-certified mechanics are being trained? I hope not.

If combustion gases are being injected into the coolant, they should've discovered that before replacing everything else.

Did they check to make sure the car's coolant temp gauge is accurate? It is possible that air in the coolant was not bled properly but you may have the last mechanic give his opinion, since he replaced the head gasket and most likely charged you a good amount of money.

 

I actually didn't pay Firestone anything. The manager apologized to me they hadn't done a block test early on and waived all the charges.

The mechanic who replaced by head gasket I'm shying away from a bit. He's been talking about how "a car this old, we should just replace the engine" and wanting to do that.

I even said to him "If the fan isn't coming on when it should, if we replace the engine would it still be overheating".

His response was "Yeah". He didn't expand on it or say "I'll can check out the fan" or anything. Why I'm trying to get other opinions so I can see what steps I should take as I go forward.

 

The radiator could be clogged. Also if the brass fins corrode and fall off of the outside of the radiator core, that kills the radiator's performance.