Why did my car overheat?

[Pundit]

Tonight, I got stuck in traffic for 1/2 hour. I'm driving in 1st and I notice smoke rising from under the hood. The temp is at max. So I pull over on the shoulder and take a look. What looked like coolant (it was dark) was pouring onto the ground. So I waited for 1/2 hour until the temp dropped and by that time the traffic had cleared. I drove home and the temperature started dropping because I was going fast. Of course, my mother (who I was supposed to pick up) decided to take the bus home.

I just got this car recently and I know that the previous owner didn't like to mix water in with the coolant as you're supposed to. Could this be the cause of the overheating?

 

[fastz28]

thermostat may be stuck. did you see any leak in the radiator?

 

[dirtboy]

There's nothing wrong with running 100% coolant. As far as overheating when idle, could be a couple of things like the thermostat or a fan. If coolant was pouring all over the place, you may want to check all the hoses as one may be worn. Definitely have your car looked at by a radiator shop.

 

[notfred]

Coolant is suppsoed to be mixed with water, it works better that way. However, I doubt that jsut running pure coolant would cause a car to overheat when idling.

Could be anything from a bad thermostat ($7) to head gaskets (over $1000)

Maybe air in the cooling system, clogged up or worn out radiator, blocked coolant line, bad water pump, etc....

edit: does your car have an electric fan? maybe it's dead.

 

[Zenmervolt]

Since the engine cooled down again when you were moving more quickly, it points to either a fan or a thermostat. Anything more than that and you would overheat all the time. Pure anti-freeze will actually perform better than pure water, so I don't think that's the reason. If it ever happens again, turn the heater on full blast. The heater gets its heat from the coolant, so if the heater is on it will reduce the coolant temperature.

ZV

 

[d33pt]

NO, pure water performs better than pure antifreeze/coolant.. the reason why you mix in the coolant is for its anticorrosive/antifreezing properties.. if you didn't blow your head gasket, just do a 50/50 mix and you should be ok...

 

[Zenmervolt]

<<the reason why you mix in the coolant is for its anticorrosive/antifreezing properties..>>

Actually, anti-freeze also increases the boiling point. Look here, and note that higher percentages of anti-freeze have higher boiling points than pure water.

ZV

 

[Pundit]

<< thermostat may be stuck. did you see any leak in the radiator? >>


Couldn't really see, it was dark. I'll check again in the morning.



<< Coolant is suppsoed to be mixed with water, it works better that way. However, I doubt that jsut running pure coolant would cause a car to overheat when idling.

Could be anything from a bad thermostat ($7) to head gaskets (over $1000)

Maybe air in the cooling system, clogged up or worn out radiator, blocked coolant line, bad water pump, etc....

edit: does your car have an electric fan? maybe it's dead.
>>


I was only driving for 1/2 hour, so I think it is more than just a bad thermostat. This car (V6 Mustang) has a problem with the head gasket, but from what I understand, the previous owner had it replaced recently.



<< NO, pure water performs better than pure antifreeze/coolant.. the reason why you mix in the coolant is for its anticorrosive/antifreezing properties.. if you didn't blow your head gasket, just do a 50/50 mix and you should be ok... >>


I'll do a mix and check the fan. The guy even warned me to watch carefully for overheating.

 

[ElFenix]

<< Actually, anti-freeze also increases the boiling point. Look here, and note that higher percentages of anti-freeze have higher boiling points than pure water. >>

that only really helps if the coollant can hold more heat/degree than water, otherwise water still cools better.


if its hot out you can turn the heater on in the car and roll down the windows to blow more heat off.

 

[Zenmervolt]

<<I was only driving for 1/2 hour, so I think it is more than just a bad thermostat.>>

A half-hour is more than enough time for an engine to overheat if it's above freezing. My car is generally at operating temperature within ten minutes. It can overheat in fifteen minutes or less from a cold start. I'll say it again, if the problem was something other than a dead fan or a stuck thermostat the chances of things getting better with speed are virtually nill. Everything points to a dead auxiliary fan or a dead thermostat.

ZV

EDIT: <<that only really helps if the coollant can hold more heat/degree than water, otherwise water still cools better.>>

Wouldn't it be kind of pointless to use anti-freeze that had a lower specific heat than water? I mean, adding something that has a lower specific heat would reduce the cooling properties of the mixture, wouldn't it? The entire reason for mixing ethylene glycol with water is to get a mixture with a higher specific heat, thereby lowering the freezing point and raising the boiling point. Why would anyone put something in the mixture that would be less effective than pure (distilled) water? It doesn't make sense. I could be completely wrong in my reasoning, but I can't think of another logical explanation.

 

[notfred]

<< (V6 Mustang) >>



It's a 94 or 95 car, right? One of your head gaskets is toast. Jsut wait till next week when you're driving w/ the heat on. The heat will start blowing cold air, and 5 minutes later you'll be on the side of the road w/ the hood open.

I know, I've had it happen, I used to have one of those cars.

Ford will cover the replacement head gaskets if it's within 7 years of manufacture, after that, you've got to pay it. if your car was a very late '95 model, you still might get it fixed for free. Take it to ford tomorrow.

 

[notfred]

[/i] >>

that only really helps if the coollant can hold more heat/degree than water, otherwise water still cools better.[/i] >>



Yeah, but antifreeze cools better than steam.

 

[Pundit]

<<

<< (V6 Mustang) >>



It's a 94 or 95 car, right? One of your head gaskets is toast. Jsut wait till next week when you're driving w/ the heat on. The heat will start blowing cold air, and 5 minutes later you'll be on the side of the road w/ the hood open.

I know, I've had it happen, I used to have one of those cars.

Ford will cover the replacement head gaskets if it's within 7 years of manufacture, after that, you've got to pay it. if your car was a very late '95 model, you still might get it fixed for free. Take it to ford tomorrow. >>


Well, it's a '94 so I guess I'm fvcked. And I bet it's pretty expensive to replace. I thought the previous owner had replaced it

BTW, since I'm not too car savvy I was wondering: how many head gaskets are there? (I assume two) Could they both go kaput?

 

[etech]

I'm not advertising or recomending the product. I had seen this the other day about the heat transfer of water vs. water/ethelyene glycol mix.

WaterWetter®
Water has twice the heat transfer capability when compared to 50% glycol antifreeze/coolant in water. Most passenger automobiles have a cooling system designed to reject sufficient heat under normal operating conditions using a 50/50 glycol solution in water. However, in racing applications, the use of water and WaterWetter® will enable the use of smaller radiator systems, which means less frontal drag, and it will also reduce cylinder head temperatures, even when compared to water alone, which means more spark advance may be used to improve engine torque.



When your car is getting hot when stuck in traffic, turn the heater and fan on full. It will help cool it down some.

If it is the head gasket, it won't help much but I thought I'd throw it out there anyway.

 

[Aceman]

I'd check the headlight fluid level immediately tomorrow

 

[Pundit]

<< I'd check the headlight fluid level immediately tomorrow >>


lol, and since my lighter is missing (it really is) I'll go get one installed for $80

Well, I just called the previous owner's daughter (my gf) and it turns out he did have the head gasket replaced. I'm guessing he got a used part and was damaged. I'm taking it back to him who will take it back to the garage and get it replaced since it is still under warranty So, I'm stuck with my gf's Thunderbird until it's fixed

 

[Aceman]

<< lol, and since my lighter is missing (it really is) I'll go get one installed for $80 >>



don't waste your money on that foolish repair. Just buy a 12V Bic for a $1.99 at the 7-11 and stick it in the cigarette lighter charging unit.

 

[Chaotic42]

<< Well, it's a '94 so I guess I'm fvcked. And I bet it's pretty expensive to replace. I thought the previous owner had replaced it

BTW, since I'm not too car savvy I was wondering: how many head gaskets are there? (I assume two) Could they both go kaput? >>



Head gaskets are cheap (mine was like $10). If you know what you are doing, you can replace it in like 30 minutes.

Heads are expensive and difficult to replace. I think a head gasket would just leak oil, but I'm not 100%.

 

[Linux23]

pardon my ignorance, but what is a head gasket used for?

 

[Pundit]

<< pardon my ignorance, but what is a head gasket used for? >>


I'm glad I'm not the only one that's ignorant. Time for me to learn about auto mechanics.

 

[Aceman]

It forms a seal between the head (top half of the engine ) and the bottom half of the engine. A bad head gasket will lead to water and oil leaking. If that water leaks and doesn't cool down the head, your head will crack or warp. Cracked or warped head means big $$$$ to replace for machine back to a perfect fit again.

 

[sten]

The first question is how much antifreeze was in it? When was the last time it was checked, and how much did it have after this happened? How much is in it now?

Sounds to me like the fan isn't pulling hard enough -- be sure to have the fan clutch and or electrical fans checked. Also, many cars overheat because the radiators are full of sludge and stopped up internally.

Also, a bunch of dead bugs blocking the airflow won't help it any. Don't ask how I know that.

I'm not convinced it is a blown head gasket. It seems to me that if the coolant was lost through a leaking gasket, the engine would have just kept getting hotter, as Zenmervolt pointed out. Also you would have noticed white smoke and possibly even liquid antifreeze coming out of the tailpipe. If the head gasket is leaking, coolant will be missing and it won't be in a puddle under the car.

If the thermostat stuck shut it would probably have blown something apart. It certainly wouldn't cool the engine when you started driving again, because cool water to the engine would be cut off.

In short, I don't think it's time to panic yet. I would check it to make sure it's full of coolant and that there are no visable leaks or blockages to air flow. Then I would let in run in the driveway and see if it overheats (or leaks). If it still overheats when you know that it is full of coolant, then it isn't the head gasket.


sten

 

[Chaotic42]

<< pardon my ignorance, but what is a head gasket used for? >>



I've learned quite a bit (I say this, still knowing nothing, relative to mechanic types, about cars) from
Edmunds.com Forums.

Lurk there, post a bit. It's a nice forum.

 

[Pundit]

<< The first question is how much antifreeze was in it? When was the last time it was checked, and how much did it have after this happened? How much is in it now?

Sounds to me like the fan isn't pulling hard enough -- be sure to have the fan clutch and or electrical fans checked. Also, many cars overheat because the radiators are full of sludge and stopped up internally.

Also, a bunch of dead bugs blocking the airflow won't help it any. Don't ask how I know that.

I'm not convinced it is a blown head gasket. It seems to me that if the coolant was lost through a leaking gasket, the engine would have just kept getting hotter, as Zenmervolt pointed out. Also you would have noticed white smoke and possibly even liquid antifreeze coming out of the tailpipe. If the head gasket is leaking, coolant will be missing and it won't be in a puddle under the car.

If the thermostat stuck shut it would probably have blown something apart. It certainly wouldn't cool the engine when you started driving again, because cool water to the engine would be cut off.

In short, I don't think it's time to panic yet. I would check it to make sure it's full of coolant and that there are no visable leaks or blockages to air flow. Then I would let in run in the driveway and see if it overheats (or leaks). If it still overheats when you know that it is full of coolant, then it isn't the head gasket.


sten >>


sten, now you have me wondering because the coolant reservoir was full. And I don't think I noticed anything but water coming from the tailpipe (as it should). I'm going to have them look at the fan. I noticed a few small pebbles scattered in the radiator, but never saw bugs.

Thank to all for your help and advice.

 

[Zenmervolt]

<<If the thermostat stuck shut it would probably have blown something apart. It certainly wouldn't cool the engine when you started driving again, because cool water to the engine would be cut off.>>

Thermostat also triggers the low speed auxiliary fan in some cases. The thermostat in my car failed and whenever I got below about 30 mph the temp drifted upwards quite quickly. As soon as I was moving at more than 45 mph things cooled down again. Replaced just the thermostat and everything was fine. The way I was able to check my fan was by turning on the A/C. The A/C overrides all settings and forces both the main and the auxiliary fan to run. When I switched on the A/C, both fans came on so I knew that the fans were fine. A failed thermostat can cause exactly the symptoms described. I agree that it does not sound like a head gasket because: 1) it got better with speed and 2) you didn't see any smoke/coolant coming out the tailpipe. Thermostats rarely fail completely shut, what probably happened is that it's not opening all the way so the coolant flow is restricted. Also, if it's not opening all the way, that means it's not triggering the low speed fan in some cases. I know that in my car the thermostat trips the switch for the low speed fan unless the A/C is on.

Since the coolant reservoir was full, you were probably losing coolant out of it and not out of the head. Remember that the reservoir is also the overflow tank and if the car overheats (causing the coolant to expand greatly) that the excess coolant is forced into the reservoir. Once things cool down, the excess returns to the system from the reservoir. If the reservior is completely full, then any excess from the system will overflow out of the reservoir.

ZV