Overheating - radiator cap is cool

[Atreus21]

Yesterday I was doing some stressful driving (traffic in hot weather) and she started inching higher and higher on the thermometer, until I started seeing steam coming from the hood, and the smell of something. It smelled literally like burning coolant. I could smell the sweet coolant smell, and something burning with it.

Pulled over, popped hood. Steam was being forced from something near the front of the engine. (This is a 98 3800II camaro by the way.) The light was bad, so I couldn't quite tell if the steam was coming from the hose leading to the thermostat or not. I was able to remove the radiator cap with no trouble. She's not leaking coolant, or at least, I don't think lack of coolant caused this.

Additionally, when I hit the brakes, or otherwise wasn't accelerating, I felt a severe rattling, like someone rattling a golf ball in a coffee can, coming from it felt like underneath the car.

Also, I recently replaced the thermostat, but failed to replace the circular gasket that fits around the thermostat in its housing, which I assume serves to force water through the thermostat and not around it. In other words, even if the thermostat was stuck, coolant could still get around it.

Pre-existing conditions:

- Water pump replaced a year ago.
- Thermostat replaced about 6 months ago.
- Crack in manifold repaired (not replaced) about 3 months ago.

Symptoms:

Overheating
No loss of coolant apart from the steam forced from the engine
Rattle under car

I fear the worst. Any ideas?

[lil' jon]

Re: Overheating - radiator cap is cool

I was able to remove the radiator cap with no trouble.

You took the radiator cap off while the car was overheated? That doesn't sound safe. Are you sure there's coolant in it? Wouldn't you get a face full of scaulding hot antifreeze if there was indeed coolant in it?

[ssms5411]

Re: Overheating - radiator cap is cool

You took the radiator cap off while the car was overheated? That doesn't sound safe. Are you sure there's coolant in it? Wouldn't you get a face full of scaulding hot antifreeze if there was indeed coolant in it?

X2 , if the car was even at 160 degrees coolant would spray out of the cap since there is 18 PSI of pressure. I'm thinking no water/coolant in the radiator or resivor.

[ne0hisda0ne]

Re: Overheating - radiator cap is cool

You took the radiator cap off while the car was overheated? That doesn't sound safe. Are you sure there's coolant in it? Wouldn't you get a face full of scaulding hot antifreeze if there was indeed coolant in it?

If that's true, then he has no pressure built up in the system...water and heat create steam which creates pressure. The steam you were seeing was prolly the engine letting pressure escape from somewhere. I think you might want to fear the worst on this one. Don't quote me though.

How long were you driving it before you started seeing steam?

If it was pretty quick after you had just started her up from sitting cold for a while. Then it would make more sense why you didn't have a geyser shooting out of your radiator when removing the cap while under pressure. Like lil' jon has stated...

[ssms5411]

Re: Overheating - radiator cap is cool

Stressful driving in hot weather and steam from engine with no coolant= engine or heads warped and toasted rattling sound is probably the engine taking a dump, my guess rod bearing or something like that from over heating.

[Atreus21]

Re: Overheating - radiator cap is cool

That's what's so weird about this. The engine didn't really get that hot, and it's gotten hotter than this without shooting steam. It got to just about the 210 mark when the steam started. I was driving about an hour before then.

When the manifold was leaking coolant awhile back, it got very near to the red mark without giving off steam. And that happened a few times.

It just occurred to me that I never actually made sure that I had coolant. I just added 4 liters (two 2 liters bottles) of water into the radiator. Something tells me that's a lot. The car starts fine, and that implies to me that there's nothing horribly wrong with the car.

I'm beginning to wonder if the seal on that manifold repair held.

Fellas, if this turns out to be something as stupid as what I'm afraid it might be, I apologize for wasting your time and effort, not to mention bandwidth.

[ne0hisda0ne]

Re: Overheating - radiator cap is cool

That's what's so weird about this. The engine didn't really get that hot, and it's gotten hotter than this without shooting steam. It got to just about the 210 mark when the steam started. I was driving about an hour before then.

When the manifold was leaking coolant awhile back, it got very near to the red mark without giving off steam. And that happened a few times.

It just occurred to me that I never actually made sure that I had coolant. I just added 4 liters (two 2 liters bottles) of water into the radiator. Something tells me that's a lot. The car starts fine, and that implies to me that there's nothing horribly wrong with the car.

I'm beginning to wonder if the seal on that manifold repair held.

Fellas, if this turns out to be something as stupid as what I'm afraid it might be, I apologize for wasting your time and effort, not to mention bandwidth.

I am willing to bet your right with the intake manifold leaking or valve cover gaskets. Check your oil to see if it's dark brown or light brown...

[Mad Max]

Re: Overheating - radiator cap is cool

Probably the first thing to do is wait until the engine is stone cold. Open the radiator cap and make sure your radiator is totally full. Next, check the overflow and fill to the correct line. BTW - use a 50/50 mix of antifreeze, preferably long life coolant. Don't mix different colors - there is orange, green, yellow etc. Each has a different use. Some are for aluminum blocks/heads, a combination of aluminum and iron, etc. Read the label for your specific application.
Once you are sure the cooling system is full, drive the car to operating temperature. Return home and let the car idle. Watch the temp guage to make sure it doesn't run hot. You should hear your cooling fan come on. If it doesn't, and the engine runs hot at idle, you need to find out why your fan isn't working. Also, if the fan is working, check under the car for antifreeze leaks. Find a spot that is clean and dry to park. The intake manifold - as you know - is a problem. Have it repaired correctly. There are aftermarket improved intake gaskets that usually solve this problem. It's alot cheaper to fix a small problem like an intake leak than it is to replace a toasted engine.
Hope this helps a little.

[steddy]

Re: Overheating - radiator cap is cool

Sounds like the intake gaskets to me also, or, maybe the heater core has a blockage. If the cap is cool, the coolant's not making it to it. Somewhere after the radiator, there is some sort of blockage, or it's escaping through the intake. I wouldn't run the motor till you find it, even when it's cold. That ratling you heard sounds like the heat was breaking down the oil, making the bearings very susceptable to being destroyed. It really doesn't take much. Take a look and see if you may be able to see signs of steam cleaning on either the right or left side of the top of the motor.

[Atreus21]

Re: Overheating - radiator cap is cool

Okay, I'm an idiot.

Whatever hose that leads to the thermostat housing has a leak, a big one. Once I started adding water to the radiator, the leak became quite apparent. Is that the lower hose or the upper hose?

[ssms5411]

Re: Overheating - radiator cap is cool

Okay, I'm an idiot.

Whatever hose that leads to the thermostat housing has a leak, a big one. Once I started adding water to the radiator, the leak became quite apparent. Is that the lower hose or the upper hose?

Thats the upper hose which when your thermo opens it lets the coolant into the engine to cool it off, the bottom hose going into the radiator is the return hose that goes back into the radiator with the hot coolant waiting to be cooled bt the radiator. You might have damaged something if the engine wasn't getting cool coolant so after you fix it and fill the radiator and coolant resivor up and hear a knocking sound you might have messed something up like previosly stated. So be ready for it, make sure there is no coolant in your oil and vise versa.

[Atreus21]

Re: Overheating - radiator cap is cool

Thats the upper hose which when your thermo opens it lets the coolant into the engine to cool it off, the bottom hose going into the radiator is the return hose that goes back into the radiator with the hot coolant waiting to be cooled bt the radiator. You might have damaged something if the engine wasn't getting cool coolant so after you fix it and fill the radiator and coolant resivor up and hear a knocking sound you might have messed something up like previosly stated. So be ready for it, make sure there is no coolant in your oil and vise versa.

Just to be clear, the hose I mean is the hose to the right of the radiator (when facing the engine). That's the upper hose?

[steddy]

Re: Overheating - radiator cap is cool

Thats the upper hose which when your thermo opens it lets the coolant into the engine to cool it off, the bottom hose going into the radiator is the return hose that goes back into the radiator with the hot coolant waiting to be cooled bt the radiator. You might have damaged something if the engine wasn't getting cool coolant so after you fix it and fill the radiator and coolant resivor up and hear a knocking sound you might have messed something up like previosly stated. So be ready for it, make sure there is no coolant in your oil and vise versa.

ssms is right on the money. Replace the upper hose going to the T-stat. Change the oil to be sure there's no coolant in it. Fill the radiator, bleed the system and be sure there are no more knocks. Good luck and hope it works out for you

[landj]

Re: Overheating - radiator cap is cool

Also, I recently replaced the thermostat, but failed to replace the circular gasket that fits around the thermostat in its housing, which I assume serves to force water through the thermostat and not around it. In other words, even if the thermostat was stuck, coolant could still get around it.

Some water may trickle by. But what's sealing the housing to the block if that rubber gasket isn't there?

[Mad Max]

Re: Overheating - radiator cap is cool

It you're putting on an upper hose - the one to the t stat housing, then make sure you put the correct gasket and seal for the t stat. Mix a 50/50 or prediluted anti freeze and fill to top. Check your oil on the stick. If it looks like a thick coffee shake, you have problems. Most likely this will not be the case. Don't run the engine if the oil looks strange. If it looks ok, run until it reaches operating temp, at idle, then shut it off. Check coolant level after the engine is stone cold and fill if needed.
Good suggestion to change the oil anyway (with the filter) and I suggest that Lucas additive. That stuff is good crap. You may be lucky and have no more problems. :cool: