Still Running Hot

You can't check coolant level with the cap removed as the system is designed to be closed with a 16 psi pressure relief cap. So, fill the rad and the overflow bottle (actually it's called a degas bottle by Ford). Bring the engine up to operating temperature. Any trapped air (now steam) should be expelled into the degas bottle. Just make certain that as the engine cools the degas bottle isn't emptied thus allowing air to be drawn back into the system. If after you have done this and there is still concern there may be an air pocket repeat but this time raise the driver's front of the car as high as the jack will allow. This will assist in bringing any trapped air/steam to the highest point where it can be bled off into the degas bottle.

ry94stang50 said:

Yeah I rarely go fast enough for 5th gear as all the roads are 35-45 mph roads..how would a 180º stat make the temp higher I think the oem is 192 right? So shiuldnt it runa little cooler on the gauge...I hhaven't done anything when the sending unit yet os it a possibility that's the prob...and also I notice that whenever I use any power accessories like light wipers blinkers anything that draws power from the battery the gauge will slightly move...example when my foot is on the brake at a light or something it will make it hotter and when I take foot off it bounces back down not a hugh bounce but I can notice it on the gauge...could that mean its a bad groundbor something of rhat nature?

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Yes, okay, two things. Yes, the factory thermostat is a 192. A 180 can actually make the coolant temp hotter because it opens before the coolant in the radiator has had the proper amount of time for its heat to be dissipated by the fan, incoming airflow, and radiator itself. Thus, the coolant which is in the rad, which is too warm, goes into the already hot block, and the hot coolant that was in the block replaces it in the rad only to continue the cycle. In many cases a 180 is not good for the car.

Furthermore, the Ford engineers and software programmers spent millions of dollars and countless hours designing the cooling system to work, well, as a system. For example the cooling fans come on at about 190 degrees. The ECM also relies on a certain engine temp for open/closed loop operation. Throwing a 180 stat in changes those variables. Also, even with under drive pullies your car should not need a 180 stat if all other cooling system components are working properly. If it does need it, then you are most likely band aiding another issue that will eventually catch up to you.

You outta think about a Motorcraft 192 stat. Trust me, no Mr Gasket, no aftermarket, a Motorcraft stat. Also get a Motorcraft radiator cap and your two sensors from Motorcraft. This way you KNOW you are not getting dud or cheapo products out of the box. Somethings need to be OEM and those items are the somethings.

Secondly, check your grounds. If they are bad you cannot trust your gauges. However, your coolant bubbling over while idling is a separate issue from the possible ground issue.

My suggested fix is this:

1) pressure test the radiator. If it holds pressure, then make sure its flushed. If its old or has had rusty or tap water buy a factory replacement from autozone or pep boys for about $90 and fill it with premixed 50/50. Also get a catch container in case you need to dump your new antifreeze for further repairs (see step 6). Consider getting Motorcraft upper and lower hoses if getting a new rad. The Motorcraft lower will have the correct spring in it to prevent collapse.

2) install a Ford OEM 192 thermostat. You can get one on Amazon for $10.

3) toss your aftermarket rad cap and get a Motorcraft one from Amazon for $12.

4) make certain that the car can idle without overflowing out of the uncapped radiator while the car is parked nose inclined, vent on, a/c dial on full heat, and blower motor on high. If it cannot, check for signs of head gasket leaks (I.e., water in oil, oil in rad, compression bubbles in rad). If head gaskets are fine...

5) make sure that HEAT is coming out of the vents. If there is none and your heater isn't leaking then you still have an air bubble in the system. You need to properly bleed it out. These cars are notorious for trapping air and being hard to bleed. If you need to do this I will gladly walk you through it on the phone. If you have had the lower rad hose off this process can take hours. If all is well here...

6) check your water pump. Is it leaking? Is it making a whistling noise? If it is, replace it with a Motorcraft unit. Again, Amazon has it, even LMS has it, but get Motorcraft. If it is not leaking, nor making noise then by now the issue will be fixed.

I really suspect a failing stat, or a bad rad, or improper bleeding of the system, but not so much a water pump. After you have addressed the overheating you need to check out the 6 or 7 grounds on the car so that you get correct readings even when using power accessories. Sorry for the length of the reply. I'm willing to walk you through this if you need help.

Very informative. Thanks Joe.

What is the proper way to bleed the system?

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chaos254 said:

What is the proper way to bleed the system?

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1) The proper way to bleed the system is to have the car idling with the cap off, car's nose on an incline, ac/heat dial on full heat, and vent on high.

2) When the vehicle reaches the "R" in "NORMAL" the fan will kick on and the stock temp thermostat will be moving toward fully open shortly there after UNLESS there is an air bubble in the system. If an air bubble exists the stat will fail to open and the fan may fail to click on at the proper time because the pocket(s) of air are not what the sensors are built to measure. Thus, they will not ascertain the actual temp of the engine and overheating will occur.

3) If you have your vehicle as #1 describes and the coolant volcanoes out of the radiator then your problem (assuming parts are working properly) is an air pocket. You bleed this pocket out over the course of a few hours with the cap off. Trying to bleed it with the cap on through the degas bottle can get you a blown head gasket or worse.

Our cooling systems are a pain to bleed because the air can only move through the tiny hole at the top of the stat. Furthermore, the coolant entering the block at temps less than the stat opening have to share that same hole. This is the reason Ford engineers put a hole at the top of the stat; to allow transfer of air/fluid for bleeding purposes.

With the nose on an incline (because it puts the radiator at the highest point for the air bubbles to float to), watch the car and see if the fan comes on at the "R," and if the water begins to flow about the same time. The water flowing into the block will be indicated by a corresponding drop in the radiator. If this does not happen shut the car off immediately because it is not going to get any better (some over flowing will happen once shut off so have a catch pan or fat wallet ready). If all works well then keep the car running and continue pouring coolant as needed into the radiator (make sure the degas bottle is filled to the "HOT" level or a little higher). If the air pockets are gone, which is what proper functioning of the cooling system indicates then just let the vehicle cycle through a few times while checking the fluid (i.e., colder to "R," and back again). The vehicle will not overheat with the cap off so long as air pockets are gone and parts are working; the car is only idling this isn't hard to cool off. If the vehicle does not work properly...

4) After having shut the car off, fill the radiator up to the top (i.e., just before syphon hole to degas bottle). Wait 5-10 minutes. During this time, assuming the nose is up, small amounts of air will exit the block and small amounts of waters will enter it. At times you can even hear this happening (e.g., running water sound). After waiting fill the radiator up again, it may only be a small amount, but if it is burping, it will nonetheless require several small amounts of water. Keep doing this routine with the vehicle off until the fluid level does not change. When the fluid does not go down any further that is indicative of a proper air bleed down. Both the block and radiator will be full of fluid. At this point....

5) Return to step #1. Let the vehicle cycle at least two times to ensure proper fluid levels with nose up, cap off, vent on high, and heat on high. You may see a drop in fluid at this juncture because an air bubble could also be in the heater core (natural highest point on a level car). The heat and vent on high ensures that the coolant reaches and fills the heater core. When the air coming out of the vents goes from ambient to convection oven hot then you know that the heater core is purged of air. This will most likely cause a drop in radiator fluid levels since air has been evacuated and fluid has entered the core. Fill it up. Watch for two more cycles adding any necessary fluid. If all is well for those 2-3 cycles, congratulations! Your system is purged of the evil air pocket monster. Put the cap on and drive till your heart is content.

The degas bottle works up to a point, but one cannot hope to bleed their system of air for the first time after repairs through it. Follow these instructions I learned from a Ford 302 guru and your system will work perfectly the 1st time.

ry94stang50 said:

Also thw new cap I have is an aftermarket with a safty lock lwver thing on it should I ditch that pos? I bought it because it looked cool haha

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Ditch it immediately! Those are worse than the regular ones. Please save yourself headaches, and cooling gremlin chases -get a Motorcraft cap off of Amazon or somewhere else that sells them. Unlike many aftermarket caps they are not duds out of the box.

ry94stang50 said:

Also one more thing when I changed the stat I noticed the prwvios owner had it in backwards (idiot) and I don't know how long it was like that I know drove it about 600 miles before the upper hose blew. Do u think that could have damaged anything in the cooling system?

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Its always possible. The 1st items I would inspect would be the head gaskets. Again, I'm happy to talk you through the bleeding process via phone if you need help.

ry94stang50 said:

Only thing I'm worried about having my car runfor a few hours. So the car won't overheat with the cap off? Damn that sounds like a pain in the ass lol...I forhot to mention when I was attempting to bleed it the temp gauge never moved from fully cold. It actually disnt move untill I drove it what does that mean is that normal?

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If you have the proper parts on the car and if they are working fine, and if you follow my directions in order then your car will not over heat with the cap off. Remember, if the water starts to gush out wildly, regardless of the gauge readings, shut the car off. This indicates an air pocket and needed bleeding.

These cars are indeed pains to get it right,. So do it right once my friend.

The temp gauge will not read accurately if either of the sensors are shot (that's why I suggested earlier that you replace both sensor & sender), or if there is too much air in the system. The reason it moved when you drove it is because you created MUCH more heat in the system by the increased internal combustion process and possibly rising fluid levels. Chances are that the block way MUCH more hot than the meter indicated. This is normal, not safe, when driving a car that has not been bleed properly. Know what else is normal under those conditions? Blown head gaskets. Don't drive it until you've addressed the issue.

ry94stang50 said:

Also what is a cycle and how can u tell when it has ran a full cycle? Sorry guys apperently I don't **** about this cooling system my jeep and camaro were easy to rid of air matter of minuetes...and this mustang can take hours? I'm beggining to get nervous hahaha

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A cycle is at its peak when the fan kicks on at the "R" in "NORMAL," and the fluid from block to radiator exchanges shortly thereafter, indicated by the temp meter returning to a cooler position.

Since one cannot trust the gauges until the air is bled out you will be relying on the temperature coming out of the vents and the coolant level. If the level is low, fill it. If the coolant begins gushing, not steadily flowing out, turn it off.

ry94stang50 said:

And joe its gonna be hard to do this over the phone since your in cali and I'm in hersey damn time zones ill prob be working on it while its the middle of the night there

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no problem because im 3 hours behind you. Your 12 midnight is my 9pm. I'm willing to help if you need it.

ry94stang50 said:

Ok guys I'm going to attemt to bleed the sytem tomorow. Hopefully I can get it right.actually ill just wait untill I can get all the morcraft stuff.

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Motorcraft stuff works right every time. Good deal man. Take the junk parts variable out of the equation.