Crimsonnaire

iTrader: (1)

Hey, guys.

I recently had my 50/50 Prestone green antifreeze boil after some revving when I got home from work. I popped off the radiator cap shortly after and a lot of it spewed out with a ton of steam. When I asked a technician, I was told that, 9 out of 10 times, when this happens, it's due to the antifreeze having too much water mixed in and that what I need is a radiator flush. However, because the antifreeze was poured in earlier this year when I installed a bypass hose in place of the heater hose, the only way for water to have gotten in is through condensation and I really can't see that being the case because the car's only seen cold weather in the recent weeks. For this reason, I'm inclined to believe that it was the actual antifreeze that was boiling. Yet, at the same time, I'm confounded by the fact that, while I was revving, the temperature gauge was right at the 210 mark and the clutch fan never turned on. So, if the antifreeze was boiling and not water, it would mean that both my thermostat and temperature sensor are faulty...

Just for clarification, I did encounter odd moments of overheating from the temperature gauge where the clutch fan kicked on for less than a minute before having the gauge returning to around the 210 mark and the fan going off. Once, I drove under completely normal condition and, after parking, I started up the car to reposition it, and the clutch fan kicked on with the temp gauge at around 230 as soon as I turned on the engine--yet, it never overheated while I was driving.

Can someone please provide speculation as to the problem?

Also, if the antifreeze reaches boiling, does that immediately put the head gaskets on the verge of blowing?

Any input is greatly appreciated.

RPM WS6

iTrader: (3)

Clutch fan? This must be something other than a 4th gen F-body.

Regardless, you may have a combo of issues here. The boiling point of water is raised under pressure, but if the radiator cap is faulty then the system may not be holding proper pressure (thus boiling will occur at a lower temp.) In addition, even though you added a 50/50 mix, perhaps the mixture in the rest of the system was already weak/heavy on water, so the ratio might be less than 50/50 (favoring water.) Have you used a coolant tester to check the mix?

Not sure on the accuracy of the temp gauge in question, because you haven't specified the vehicle. Again, I assume this is not a 4th gen as they didn't use a clutch/crank powered fan.

Zmg00camaross

iTrader: (11)

I would make sure your radiator is not block, change the thermostat and change radiator cap. Also must purge all air out of the system otherwise you will get air pockets and can cause a random overheating issue!

kingtal0n

iTrader: (1)

1. water is better than coolant at controlling temperature, i.e. preferable for race cars
2. track rules state that cooling systems must use 100% water (coolant is not a necessity nor a requirement for effective cooling)
3. always use distilled water in cooling systems


now, on to overheating issues,
A. ensure water is flowing (water pump is working, and no clogs)
B. remove all air from coolant system (many have a highest point/ bleed valve) you may need to bleed then re-bleed some cars
C. ensure the fan systems are operating properly
D. check radiator for blockages of airflow (debris like leaves)

other info:
street cars need at least a 165*F Thermostat, 180* is recommended for many applications. Best economy is often achieves around 212*F. Low water temperatures (sub 150*F) are associated with pre-mature engine wear.

wssix99

iTrader: (5)

Time Out!




How do you know it was "boiling"? Did you hear a noise? If so, how could you hear that noise when the engine was revving? Are you saying that you heard the "boiling" noise in the compartment after revving the car but the temperature gauge was normal and the fans were off?


Don't do this. If you do, coolant will spew out with a ton of steam. As mentioned above, the system is a pressurized one, so anytime you open the radiator hot - the pressure will escape and water will turn to steam once it hits (lower) atmospheric pressure.


This is bull ****. 10 out of 10 times, the technician tells you this so they can sell you an unnecessary service and steal your money.


You shouldn't do this, either. No good can come from it and you shouldn't be hanging out with the type of women who are turned on by it, anyway.


If the car is reading a normal temperature, the fan won't come on - so I'd think this normal.


Testing your temperature sensor is easy to do with an electrical tester, some (real) boiling water, and instructions you can search for on the internet.

I'd be open to the possibility that your coolant was the proper temperature and not "boiling." I'd also think your radiator cap is good because if it wasn't - the pressure and steam would have escaped before you opened it up.

Are you running a stock thermostat?

LLave

iTrader: (3)

Lol... you took a radiator cap off a hot car and it boiled, and this is out of the ordinary how? The reason cooling systems don't boil is because they are pressurized, if you open the system it will flash boil. This is pretty normal.

Crimsonnaire

iTrader: (1)

Thank you all for chiming in. Sorry I wasn't fully clear to begin with.

I heard gurgling sounds and felt vibrations after I turned off the engine, so it must've started to boil while I was revving. Yet, the temperature gauge was around 210 the whole time, and the radiator fan never kicked on. This is a stock LS1 in a '99 F-body.

I didn't go crazy with it. I only revved it for about 2 minutes at 1800 RPM. I do this occasionally to monitor the status of my lifter tap which I've had for a few years.

I must also agree with wssix99 that the radiator cap is most probably good, because while I was observing the engine bay at first, there was no steam coming out from anywhere, but there was obviously hell going on inside because the coolant reservoir was shaking.

I'm currently running the stock thermostat and plan to change to a 160 degree aftermarket as soon as possible.

Right now, I'm more worried about the head gaskets more than anything because the engine is presumably a high mileage and a this will be the thing that will require me to take a major overhaul of the engine or possibly swap engines altogether if I find it's more economic. Do the stock head gaskets necessarily rupture shortly upon exposure to boiling antifreeze?

The way I see it is that it was either the antifreeze that was boiling hot or it was an overabundance of water, and I doubt the latter because I've ran just distilled water in the past without any problems. So I'm going to start troubleshooting in the direction of the former since that is the more reasonable and threatening possibility...

_JB_

iTrader: (33)

Sounds to me you either have air in the lines, missing air dam, too high ratio of coolant, or blocked radiator. Oh and don't bother with the 160* thermo just get a failsafe stock temp. And be careful around hot liquids (including steam).

wssix99

iTrader: (5)

I'm pretty sure nothing is boiling, so you can sleep easy tonight. Boiling is fluid turning in to gas. If that was really happening, you'd just get steam out of the car when you opened the radiator cap and you'd also get a pressure spike, which would release to your overflow and that would make a big unmistakable sound.

I'd try the following:
- Try to make it happen again with and then without the A/C running. Sometimes the A/C will make gurgling sounds...
- Recreate the sounds, let the car cool, and then see what the radiator looks like. Do you see air space?
- Try doing a pressure test of the cooling system.

If the sound is really coming from the radiator and not the A/C evaporator, maybe you are getting some exhaust or other gasses in the system and they are separating out when the pump stops and the system looses some pressure? The pressure test may point to something like this.

Crimsonnaire

iTrader: (1)

Yeah. I've thought it over and realized I should stick with the 180 degree thermostat so the engine can boil off moisture from the oil more efficiently in the winter.

Believe me, I wish my antifreeze wasn't boiling, but the sound and vibrations I experienced is rather unmistakable. And as I initially said, there was a ton of steam that came out when I popped off the radiator cap.

But I recently picked up a crucial piece of information: 50/50 antifreeze boils over at 265 degrees Fahrenheit, and it's a little hard for me to believe that my temperature sensor was off by that much. So if it was excessive water that was boiling, it would've had to reach a temperature for it to be able to do that, which would've had to be considerably higher than 210, since I've ran mostly distilled water in the past without it ever boiling. So my question now is: just how much water and how high a temperature does it require for it to boil? Morever, if water boils inside, is the pressure equivalent to the pressure that exists when 50/50 antifreeze reaches around 260? (Again, I'm mostly concerned about my head gaskets and trying to ascertain their likely condition at the moment.)

Since refilling the antifreeze, everything seems to be normal as before, but I haven't revved it at a still like before. When checking the oil, I saw a bit of moisture sludge at the tip of the dipstick, but I don't know if that came from a leaking head gasket or from rapid condensation from when I let the radiator cap off and the hood open 'til the engine was cold. I plan to get the thermostat and temperature sensor changed ASAP.

1 FMF

iTrader: (1)

see attached pic showing coolant boiling points in relation to pressure and antifreeze concentration.

the oem radiator cap is supposed to hold pressure up to 16 psi.

the coolant reservoir which is under the battery, is connected to the radiator neck by a little hose to where the radiator cap is. nothing will flow into this coolant reservoir until the pressure of the radiator cap is exceeded, which should be around 16 psi.

one possibility is coolant boiling within the radiator, and once the pressure rating of the radiator cap is exceeded will allow this boiling coolant to flow out into the reservoir. but the boiling would stop and just be very hot coolant in the reservoir.

coolant won't boil in the coolant reservoir, just like pouring rapidly boiling water out of a teapot into a cup, it does not boil in the cup because there's no longer a heat source.

other possibility is coolant is not boiling, but pressure from cylinder combustion (100+ psi) is leaking into the coolant system and raising pressure of the cooling system greater than the radiator cap can hold. When this happens you would get a garden hose type of flow into the reservoir... possibly causing the reservoir to shake and give the impression coolant was boiling in it... or as combustion gasses are forced into the cooling system they are making their way into the coolant reservoir where those gases are escaping rapidly and giving the impression of boiling in the reservoir.

to diagnose this you would need a radiator cap pressure tester, having a pressure gauge on it. reproduce the condition and observe coolant system pressure exceed 16 psi while coolant is less than 220°F.
The electric radiator fans do not turn on at low speed until coolant temperature is 226°F, and not high speed until 234°F.

the only ways combustion gasses could raise coolant system pressure on the LS1 (someone correct me if i'm wrong) are
- head gasket failure, and this would be best case scenario
- cracked cylinder head
- cracked cylinder liner

before you jump to these conclusions, replace your radiator cap.
and if you want put a new thermostat in they are not expensive.
just drain the radiator, do not flush, do not add chemicals or garden hose water.
refill with 50/50 antifreeze & clean or distilled water.
you need to make sure to get all air out of the coolant system and the easiest and cheapest way is to drive car normally getting it to full operating temperature (180° - 220°F). next morning after it's cooled before you start engine remove radiator cap and top off radiator. do this for 2 to 3 more days, as air makes it's way out of the engine into the top of the radiator.
the morning you pull the radiator cap and coolant is right there at the top then you're done all air is out of coolant system; you need a properly functioning radiator cap, and coolant reservoir and hose that does not leak, to accomplish this; this is how the coolant system should normally function.

RPM WS6

iTrader: (3)

Very good post by 1 FMF above. Good points, solid advice.

RixTrix

Air in the system. Todays cooling systems will not tolerate any air in them.

Today's low profile hoods all have the radiator mounted very low with the cap barely above the heads. If there is an air bubble under the cap there is likely an air bubble in the heads, this causes a hot spot and makes steam, the steam displaces more water(coolant) which in turn causes more steam.........

The radiator cap has 3 seals,
the main seal that sets the pressure
a check valve that allows it to suck coolant from the recovery bottle
and the seal around the top that blocks air from getting into the coolant recovery line.

If the motor is completely full of coolant cold it will expand some, this is the reason for a pressure cap.
as that coolant expands pressure builds in the system (pressure is good it raises the boiling point of the coolant)
However some lightness is needed so the cap limits pressure to keep from ballooning radiators and hoses.
As that pressure is released any air in the system is also purged into the recovery bottle.
The hose in the recovery bottle must go to the bottom of the bottle and always be submerged in coolant.
As the coolant temp returns to normal it contracts and causes a slight negative pressure in the cooling system,
this draws coolant back into the system from the recovery bottle.
It is critical that there is a good seal at the cap and rad and the hose is good and always submerged in the remaining coolant in the bottle so as to not allow any air into the motor.

If the filler neck on your radiator has any damage that prevents the cap from making that outside seal that keeps the air out of the recovery part of the cooling system, you will have cooling problems. The recovery bottle is not an accessory or to keep coolant off the floor, it is to keep air out of the system.

Do not run a cold thermostat in your motor, your motor is designed to run at a certain temp. A lower temp thermostat will not keep your motor from overheating, it will only delay the inevitable. A lower temp thermostat will not allow an overheated motor to recover any faster. When a motor is at an unsafe temp ANY thermostat (correctly functioning) will be wide open.

A motor that is overheated will have foamy coolant which does not carry heat as well. The foam will cause air pockets which cause steam pockets which cause more foam and bigger hot spots which make more steam.

You do not want ANY air in the motor for 2 reasons.
first is air pockets (foam) which turn into steam pockets when the motor is hot,
second is corrosion and formation of deposits, air contains free oxygen which promotes corrosion.

DO NOT take the cap off a hot motor!
First is the safety issue, I wish I had a camera years ago when Pete's chest was covered with 3rd degree burns! If he did not wear glasses his eyes would have been burned!
Secondly the release of pressure causes steam pockets to form in the motor which cause hot spots which create more steam which creates bigger hot spots.

Pour buckets of water over the radiator to drop the pressure until the upper hose goes soft, then you can open the cap.

Always use distilled water, you don't want to add any minerals or compounds that contribute to corrosion or sediment. On a system with no antifreeze you need a sacrificial anode so electrolysis does not eat on the valuable parts. Electrolysis also frees oxygen molecules that do even more dirty work.... Remember the old small block Chevy with the eaten away thermostat housing? That was a sacrificial anode!

wssix99

iTrader: (5)

+1

Great chart. This is why I don't think the antifreeze is actually boiling. In order for that to be happening, the coolant temp sensor would need to be bad and/or a weird thermodynamic situation where heat is being added to the radiator after the car is shut off. But I guess a combo of a bad temp sensor/bad cap could cause this - but it's highly unlikely.


This is what I fear is happening. We can also hope that the water pump is failing and pumping raw air in to the system instead of the more negative scenarios. (This happened to me and is easy to check for - just remove the cap off the radiator after the car has cooled. If there is air space, then there are external gasses coming in.)


IMO - I'd start with a pressure test because it's free. (I like free.)

Firebrian

A couple of times this summer on 90+ deg F days I also noticed some light coolant system gurgling coming from the engine after it was off. It lasted a couple of minutes. I assumed those were pockets of flashing coolant located nearest the cylinder walls. Without a pump running to keep pushing coolant into the radiator this seemed to be normal. Though I can't recall it happening in previous years. It didn't occur in the radiator and there was certainly no banging in the overflow reservoir. My coolant is 50/50 and fresh. No signs of any abnormal fluid color, floating oil, foam, bubbles, or anything else in the coolant. It's crystal clear. I rarely drive the car in peak summer heat (there are better things to do) so maybe this is something that has been happening all the time if it's hot enough out.