Right Amount Of Coolant

[AR_Cobra]

I was having an issue with my car and decided to replace the thermostat. After replacing the stat and putting everything back together I researched on here how to properly add the coolant. I have burped the system in other cars but didn't know if that works on these due to the cap being on the expansion tank. I read one post that stated to loosen the temp bulb for the water gauge on the manifold and fill the car until coolant leaks from there. I did exactly that, took the car around the block and am having the same problem as before. I normally turn the fans on when the gauge gets to 90'C. When the fans come on it usually drops and stays right around 80'. The other day after driving around for about an hour, as I was heading home I got on the car a bit on a curvy road near my house. I noticed the gauge reading 110' and panicked. While babying the car home I watched the gauge drop back to 80'. Pulled in the garage, lifted the hood and noticed antifreeze every where. After my test drive today (with replaced stat) I monitored the car. When the gauge reads just over 100' coolant rises in the overflow tank and spews out the cap. Once the fans come on the level falls in the overflow tank. At 100'C on the gauge I am only getting a digital reading at the thermostat housing around 148'F, plus the radiator cap on the expansion tank doesn't even feel hot. Minutes after shutting the car off I can remove the cap and the expansion tank is empty. I'm starting to think I am not running enough fluid but need some advice. This has happened a few times before but it seems only after I had a friend's shop replace the cam. Maybe they didn't properly fill the coolant either?

[RICK LAKE]

AR_Cobra Did you add a couple of 1/8" air bleed holes in the thermostat before installing? Some guys raise the front ends of the cars to get all the sir to the front of the motor. 50/50 mix of antifreeze and disstilled water, and 1 bottle of water wetter. depending on what part of the country you are in. You could try and vacuum the system down first and then refill again. The other issue I have is did this problem just start??
Other possiblitys for problem are impeller spinning free on shaft, when cold you have enough flow, when hot impeller may slip. This is a long shot.
Head gaskets starting to fail. Small pin hole leak causing compression into system. How long ago was motor built? How hard do you drive the car?? What was the oil temp on the motor? Check the oil and look at it for a discolor of brown. I will stop here and hope it's just air bound and will take a couple of cycles to remove the air from the system. You did check the thermostat housing for the same temp reading on it?? Have seen them boxed wrong unless bubble wrapped. This will make the motor run hotter or colder. The missing coolant is a different thing. Start with redoing thermostat and recheck numbers and follow beginning of ideas, then write back. Take readings all around the motor and radiator also. Simple check is to boil water and make sure the thermostat is opening on the correct temp. Rick L. Ps if these idea don't work, this could get ugly. Question left out, Are you hard driving of the car??Miss shifts? Racing C.S.? or other friends? You may have lifted a head with a missed shift. Car will normally over heat after 1/2 -1 hour of running. Last thing is to check pressure in coolant system during ride. You will have to rig up a gauge of coolant pressure tester to see reading. Good luck.

[AR_Cobra]

Rick, I can answer some of your questions. I did notice that the old stat had a small hole in the flange and the new one did not. I added a gallon of 50/50 mix yesterday, nothing else. Here in Arkansas the weather is fairly mild. I don't drive the car unless it is at least 45-50 degrees outside. The motor was built back in 98 when the car was done (SP328). I purchased the car 2 years ago. Shortly after I owned it the distributor gear sheared some teeth and took some cam gears with it. A shop I know and trust pulled the cam and we had a custom one made from Comp Cams. I don't remember having this issue before that all happened. During that time it seemed like the fans were taking longer and longer to kick on. Instead of messing with the fan stat we installed an override switch on the dash. Since then I have replaced the water temp gauge with another Smith unit. The car has always run fine if I turned the fans on when the gauge reads 90'. A couple of times I forgot and the gauge got to 100', that's when it burps fluid from the overflow. I don't drive the car very hard, maybe a few hits of the throttle on a straight away (nothing like how I drive my Mustang)! The other day it was the same as always, gauge got to 90', turned on the fans, gauge dropped to 80'. After getting on the car a bit (nothing extreme) was the first time I had ever seen the gauge go to 110', but after maybe less than a minute it dropped right back to 80'. I figured the stat stuck shut so I decided to replace it. I have burped the radiator on my Mustang but didn't think I could do that on the Cobra since you don't directly fill the radiator, but the expansion tank. Is this correct or can you burp it through the expansion tank? I did take several readings yesterday and the temps I read were about 50'F lower from what the Celsius temps were on the gauge. Even took temps right at the manifold where the gauge probe inserts.

[Blas]

You should also verify that you have the thermostat installed in the correct direction, with the small drilled hole(s) in the thermostat flange at the top to allow trapped air to pass. The final coolant level in the expansion tank should be right around where the expansion tanks internal plate is (it has a hole you can feel and see inside) I should automatically adjust itself after a few heating & cooling cycles with the excess coolant being passed to the overflow tank (if you have one) Many of the overflow tanks are not the recycling design, and when they overfill, coolant sprays out of the little breather hole on the top making a mess of the engine compartment. Most overflow tanks have a valve on the bottom to empty them.
Now, regarding the temperature swings; the fans are controlled by a temperature switch located on the radiator on the driver’s side, lower, inside corner. It has two wires (grounds) that trigger a relay behind the dash that activate the fans. To check this switches operation just remove the two wires, connect them, and both fans should operate. (The car can be on or off). If your fans are not turning on or coming on at a higher temperature than in the past, this switch could be the problem.
Another thing; Since you mentioned that you had work done on your car that may have required the fans or the entire fan shroud assembly being removed...The first thing I would do is be sure both fans are operating; and that the fans are both turning in the correct direction. They both should be PULLING air into the engine compartment THRU the radiator. This is a very common problem.
Feel free to contact me if you have a problem with the fans electrics. Send me a phone number offline.

[AR_Cobra]

Thanks for your reply, Blas. I'm confident the stat is in the right direction, but I do know it doesn't have the air holes drilled. I always thought those had to do with the heater and not for letting air bypass. I drove the car yesterday to get it warmed up and watched it in the driveway. When the gauge gets to around 95' you can see fluid starting to rise in the overflow tank. Once it hits around 100-105' fluid will start out of the cap like you described. As soon as I turn on the fans with the dash switch the fluid level will drop all the way down on the overflow level indicator. The gauge will then read about 80'. What I don't get is that at 100'C is around 212'F. With my digital temp shooter I am not reading anything near that high around the engine compartment so I don't think the car is over heating.
I started noticing that it took longer and longer for the fans to kick in with the thermostat. I figured the switch was going bad and I planned to replace it. I did a little research and read that this switch can be a real pain to access and replace. Several people suggested to wire in an override switch so I installed one on the dash.
When my friend's shop replaced the cam the motor was lifted just enough to clear the cam going in. The radiator stayed in place. I'm assuming that they drained the coolant and replaced it when they finished, thinking maybe they didn't put enough in but I'm not certain about that.
Every time I take of the radiator cap on the expansion tank there is never fluid in the tank, maybe just a bit sitting in the lower portions of the ribs in the tank but nothing more. Is that an indication of not enough fluid in the system? I would think that not enough fluid would cause some erratic behavior?

[menace1]

If all else fails after checking the conditions listed on these posts, try pulling the thermo and open it far enough to slip a asprin on each side of the valve then reinstall the stat. Fill the expansion tank and that should purge the system and solve your problem. The expansion tank should always be 1/2 full.
Good luck,

Glenn

[RICK LAKE]

AR-_cobra Any chance of a first name?? It sounds like you are still air bound. Try this, remove the stat and but 2, 1/8" holes in the thermostat housing, about 180 degrees apart. Make sure and check the temp on the stat for when it opens. It said on the bottom of most stats. I am guessing you are going with a 180F stat. Install stat with 1 hole at the top of the opening. Refill the motor slow. Jack the front end off the ground as high as you can go without hitting rearend. This will take some time. Fill and let sit. When the level drops no more, cap it and put car down. Have a good size catch can for over fill hose in it. Run car until you see thermstat open and temp drop on gauge. With out fans unless temp gets into the 210F range then turn on fans. Let motor cool off and repeat this a couple of times. After 3 times make sure the level is 1/3 up from bottom of tank. Go for a drive and see what happens with motor temp. Side note, does your car have a heater?? This could also be the problem of air trapped inside causing over heating?? As far as the fans and when they come on, let fix or fine out what's going on with motor first. You get no white smoke from exhaust pipes?? after 20-30 seconds of running? If this doesn't fix the problem you are going to start looking at other things like a partially restricted radiator, fins clogged with debrie, or worse possible seeping head gasket that compression gas gets into the system ONLY when the motor is hot.
Does this motor warm up quick? like in 2 minutes or less? Mine is like 45 seconds for outside temp to 180F, It's all aluminum 482 with everything done to control temps. Lets stay with the basic first. Thermostat, burp system couple of times, same for heater if car runs one. See what happens. Getting a new fan switch wouldn't hurt with it beening 14 years old. Rick L. Ps I like Glens idea with asprin, couldn't hurt.

[AR_Cobra]

Hey Rick, the name is DJ. I will try this stuff this weekend. It takes a while for the car to get up to temp, sometimes up to 10 minutes of driving around before I hit the fans. The car had a 180 stat and that is what I put back in it. The only difference I noticed was that the old one was very easy for me to push it open. The new one is very stiff. Yes it does have a heater. I never use it and thought about taking it out, but will probably just leave it alone. I have heard that replacing the fan stat is a pain in the rear, that is why I decided to put the fans on a switch.

[RICK LAKE]

AR_Cobra DJ It's not a head gasket problem. You said the thermostat opens easier than the new open. Do the boiling water test on the stove, (when the other half is not around). Heat the water and watch the temp of it. See at what temp the themostat opens. If the spring is weak it could open at 160F. Issue with this is the motor doesn't get enough heat in it. New stat will fix this, the temps may read higher but as long as it doesn't go over 200F you are not going to hurt anything. You should see a 10-20f degree down when the new thermostat opens on the temp gauge. It will close and open a couple of times until it balances out the motor temp. After that it should be steady. Hard driving or long idles will raise the temps slowly but driving at over 30 mph will bring them down again.
Heater core lines, leave them hooked up but check for flow on them with heat going in one side and the other side a little cooler. Your gun should be able to check this. Listen or feel the hole for any wierd or funny noises. This could be air stuck in the system and causing the coolant level issues. This is why it might be worth the money to have a place vacuum the system down and fill. Try the other things first and check thermo. Good luck. Rick L. Ps more side notes Does your radiator stand straight up and down in the nose of the car or is it at an angle like ERAs? Straight up no changes on angle, ERA installs a splitter to help get more air to the top of the radiator. I run those 2 small fans in the frontend and look cool but block air to the radiator. Splitter works better for racing. The other thing is Aluminum or Copper? I went from Copper to Aluminum for weight in the nose of the car. Saved 20 pounds, Almost Some of the pro's can tell you which one works better in heat removal of the coolant. Later