Air in coolant lines? & overheats
12-11-2011, 11:31 AM
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Air in coolant lines? & overheats
I recently bought a '97 Scab, 4.6, with 221500 miles on it. This weekend, I decided to swap the coolant out. Before I did, the heat only went from lukwarm (city driving) to warm (highway). The coolant tested to 1/4 effectiveness, so the flush was scheduled.
I decided against cutting into the heater hose with a transfer kit, and opted to pull the drain plug and just keep the engine running with water flowing from a hose in the resevior. I drained the radiator and added two bottles of Prestone flush. Then, I drove it for about a half hour. Came home and pulled the drain plug and kept water flowing in the resevior. I did the drain flush for about 20 minutes, then drained the radiator again.
After adding two gallons of straight antifreeze, and two gallons of distilled water, I drove the truck again. This time, it overheated within a quarter mile. I turned off the truck for only one minute, turned it back on, and drove home. The temp gauge went back to normal and I drove home. I noticed the resevior was almost empty, so I added a 50/50 solution to fill it back up. This time, I was able to drive it about a mile or so, before overheating and spewing. Again, I turned it off for about a minute. When I turned it back on, the temp gauge returned to normal and I was able to drive back home. On the ride home, however, it did creep up into the red again. I simply turned it off and coasted for a bit, turned it back on, and made it home. Did that a couple of times.
When I got home, there was AF all over the quarter section of the engine compartment in the resevior area. So, one last-ditch effort was to change the t-stat. Cheap part, and not knowing the maintenance history, I thought it was a good idea. End result? Same problems. I gave up for the evening as it got below freezing.
One thing I noticed when I returned home were that the upper radiator hose had pressure in it when I checked it. It wasn't hot, either.
My question is: Do I have air in my coolant system, and if so, how do i bleed the air out?
Also, my heater no longer blows warm air, and I suspect that it is because of air in the lines.
Prior to all this, it never overheated for the six days I've owned it, and I did have some working heat.
Any suggestions? Thanks!
I decided against cutting into the heater hose with a transfer kit, and opted to pull the drain plug and just keep the engine running with water flowing from a hose in the resevior. I drained the radiator and added two bottles of Prestone flush. Then, I drove it for about a half hour. Came home and pulled the drain plug and kept water flowing in the resevior. I did the drain flush for about 20 minutes, then drained the radiator again.
After adding two gallons of straight antifreeze, and two gallons of distilled water, I drove the truck again. This time, it overheated within a quarter mile. I turned off the truck for only one minute, turned it back on, and drove home. The temp gauge went back to normal and I drove home. I noticed the resevior was almost empty, so I added a 50/50 solution to fill it back up. This time, I was able to drive it about a mile or so, before overheating and spewing. Again, I turned it off for about a minute. When I turned it back on, the temp gauge returned to normal and I was able to drive back home. On the ride home, however, it did creep up into the red again. I simply turned it off and coasted for a bit, turned it back on, and made it home. Did that a couple of times.
When I got home, there was AF all over the quarter section of the engine compartment in the resevior area. So, one last-ditch effort was to change the t-stat. Cheap part, and not knowing the maintenance history, I thought it was a good idea. End result? Same problems. I gave up for the evening as it got below freezing.
One thing I noticed when I returned home were that the upper radiator hose had pressure in it when I checked it. It wasn't hot, either.
My question is: Do I have air in my coolant system, and if so, how do i bleed the air out?
Also, my heater no longer blows warm air, and I suspect that it is because of air in the lines.
Prior to all this, it never overheated for the six days I've owned it, and I did have some working heat.
Any suggestions? Thanks!
12-11-2011, 12:27 PM
#2
It is possible your heater core is partialy or fully clogged. Many times it is not only clogged but leaking also. A heat gun shot on the return water line would tell you if heater hoses are perty close to same temperature. A good pair of gloves and a face shield and loosen the cap tiny will let out trapped steam and refil running outside the garage. A folded up Pepsi carton in front of the radiator will warm up the rig and you can fill bleed it until your ok. If you put the thermo in correctly getting the truck bled of trapped air will do the trick, as long as the system also holds pressure at time you will warm it up, let it cool add a qt. warm it and do it again 3/4 times. If you think you have it have the system tested to make sure it is up to psi specs when warmed to opperating temps. Removing the plugs on the sides of the engine block would have been a good way to drain the system better using teflon tape so threads will seal and plugs come out again next year. It seems fords have always been hard to refil and patience is a virtue. Heater blowing hot and cold depending on the RPM's of the motor usually means the system is low of coolant. But controls do fail. Continually running in the red zone will lead to damage. A psi test will alert you to a leaking water pump which can cause many headaches and be quite small. One never has his cooling system completely fixed until he has psi tested it. It's your simplest mistake and costliest. 
Have experienced the simple switching of the hoses at the heater can cause you fits and someone else switched them. You might look at another rig to compare. Stretch bolts in the heads do not like to be subjected to extreme overheating and head gaskets suffer the same because of it. The syphon system of your fill bottle won't work if the system isn't sealed or is too low of coolant.
Last edited by papa tiger; 12-11-2011 at 12:54 PM.
12-11-2011, 01:02 PM
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Thanks for the response, Papa Tiger.. 
I checked the water lines at the firewall and one was hot, while the other was cold. That is indicative of a blocked core. This is interesting since I didn't have this problem until I did the flush.
When say "if I put the thermo in correctly", I am assuming that there was only one way to put it in, with the spring side down, and the shorter side on top. Unless there is a different way by rotating it 180 degrees, but leaving the vertical orientation the same??
I will work on warming it up, releasing pressure, adding water.
I tried the freeze plugs, but couldn't get them loose.
Headed back outside!
I checked the water lines at the firewall and one was hot, while the other was cold. That is indicative of a blocked core. This is interesting since I didn't have this problem until I did the flush.
When say "if I put the thermo in correctly", I am assuming that there was only one way to put it in, with the spring side down, and the shorter side on top. Unless there is a different way by rotating it 180 degrees, but leaving the vertical orientation the same??
I will work on warming it up, releasing pressure, adding water.
I tried the freeze plugs, but couldn't get them loose.
Headed back outside!
12-11-2011, 05:06 PM
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take your 'stat out drill 3 small holes in it like where the one is remove that check ball thing so you have 4 hole just space them out. and you will never have air pockets again and it will run nice and cool..
12-11-2011, 05:39 PM
#6
Thanks for the response, Papa Tiger..
I checked the water lines at the firewall and one was hot, while the other was cold. That is indicative of a blocked core. This is interesting since I didn't have this problem until I did the flush.
When say "if I put the thermo in correctly", I am assuming that there was only one way to put it in, with the spring side down, and the shorter side on top. Unless there is a different way by rotating it 180 degrees, but leaving the vertical orientation the same??
I will work on warming it up, releasing pressure, adding water.
I tried the freeze plugs, but couldn't get them loose.
Headed back outside!
I checked the water lines at the firewall and one was hot, while the other was cold. That is indicative of a blocked core. This is interesting since I didn't have this problem until I did the flush.
When say "if I put the thermo in correctly", I am assuming that there was only one way to put it in, with the spring side down, and the shorter side on top. Unless there is a different way by rotating it 180 degrees, but leaving the vertical orientation the same??
I will work on warming it up, releasing pressure, adding water.
I tried the freeze plugs, but couldn't get them loose.
Headed back outside!
Dont forget to turn your heater on full heat full blast even defrost to make sure everything is on. I had a heater many years ago plug at about 12.000 miles and it was full of a gell material ran hot water thru it both ways and shook it up for probably a 1/2 hour and cleaned out. Just mine though and car was new. Should have went warranty but had time on my hands and trouble on my mind so I spent the weekend at my shop getten dirty and disgusted and suprised. Good luck. Drilled holes in LP equipment thermostats years ago to stop freeze ups of fuel systems from cold starts. That was then and LP is sooooooo cold.
12-11-2011, 06:38 PM
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Let the truck cool down and watched some TV. Pulled the stat and drilled holes. The new stat isn't Motorcraft, but a Murray from O'Reilly's.
Earlier, before TV, went ahead and installed the T line on the upper heater hose and blew out the core. Got brown goo, but it flowed in both directions. Heater got hotter than ever before, which is a good thing. But, the truck still overheated when driving. Never did overheat at idle or when holding 2500 RPM in the driveway. When we pulled the stat, there was a bunch of brown gel-like goo all over it. So, I pulled it, cleaned it, then drilled it. A friend is installing it as I type. More to follow.
Right now, as this is my only mode of transportation, other than a motorcycle... and I would rather NOT ride to work tomorrow morning in 20 degree weather... I would rather have a truck that didn't overheat with NO heat, than ride the bike in the bitter cold.
Earlier, before TV, went ahead and installed the T line on the upper heater hose and blew out the core. Got brown goo, but it flowed in both directions. Heater got hotter than ever before, which is a good thing. But, the truck still overheated when driving. Never did overheat at idle or when holding 2500 RPM in the driveway. When we pulled the stat, there was a bunch of brown gel-like goo all over it. So, I pulled it, cleaned it, then drilled it. A friend is installing it as I type. More to follow.
Right now, as this is my only mode of transportation, other than a motorcycle... and I would rather NOT ride to work tomorrow morning in 20 degree weather... I would rather have a truck that didn't overheat with NO heat, than ride the bike in the bitter cold.