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any way to bleed cooling system

8.1K views 16 replies 8 participants last post by  Zmann  
#1 ·
Truck was having issues staying warm at idle. Felt upper rad hose, to hot to hold. Felt hoses going to the heater core... not all that hot. Replaced t stat since I was going to replace the heater core, but now only have cold air blowing, no heat at all. Coolant level fine. Does this sound like an air bubble trapped? If so anyway to bleed the system?
 
#3 ·
No heat at all sounds like more than an air bubble (possible leaking head gaskets). Ford recommends filling with a RadKit Plus to make sure it is free of air pockets - but they are expensive! As Heavy Assault mentions, I have found that you can "burp" it a few times and it will eventually clear of air bubbles, if that is all that you have going on. I let the system get fully warm and then CAREFULLY vent the degas bottle (remove the cap - the quicker the better - as long as you protect yourself from possible liquid spray). SAFETY TIPS - Make sure that you have a proper coolant level (at or below the minimum level) so that you will be venting off gas and minimizing the chance to blow out hot liquid. Even with a proper coolant level, put a thick/heavy towel over the cap and top of the degas bottle to protect yourself and hands from liquid spray when you open it.

With typical 8-10 psig pressure and proper level, it should not spray out much, but the cap might have failed and it might be holding more pressure than 16-18 psig. Also, if there is a large air bubble internal to the system, it could cause it to vent more violently.

Then let it cool off and check the level. If you are removing air bubbles, you will see the cold level drop.

It will take multiple times of doing this to clear a system of air pockets.
 
#5 ·
the heater on high has no impact on how well the core is purged the heater always has the same flow unless your on max cool and they bypass/block is activated

i have a vac fill and honestly I have had the same results using it or a gravity fill

good tip on the t stat but I am with Bismic this may be a bigger issue
 
#6 ·
Ford did the heads with studs a couple months ago, but I worry they never fixed the problem. I guess I need to explain a little more. My oil cooler failed a month ago. I ended up having oil in the coolant. So I replaced all that, ran restore and vx9 or whatever is called through it. Replaced thermostat, replaced coolant filter, broke plastic nipple going to degas bottle on radiator. Ended up putting a brass fitting on the radiator. Filled the truck with elc cat rated coolant, no silicates. Had heat, no problems. Then the brass fitting ended up failing, so I replaced the radiator. after that I started having problems with the truck staying warm at idle. The water gauge would drop below normal temp and start blowing cooler air. So I figured bad thermostat, and since the hoses going to heater core were not hot, I had a bad heater. Replaced both last night, and now the water gauge doesn't drop. Sits right in the middle, but FREEZING cold air when I blast the heat. Drove 30 miles this morning, opened the degas cap, heard a little pressure come out. Coolant was a little below minimum before I took the cap off, than the coolant level raised to minimum. Still cold air.

Someone point me I'm the direction to check everything is working properly.

Also can someone explain to me how to check heads, and if there is a way to check off Ford actually put my studs in. I'm pretty fed up with them right now.
 
#8 ·
Also can someone explain to me how to check heads, and if there is a way to check off Ford actually put my studs in. I'm pretty fed up with them right now.
i can see my front passenger side head bolt kinda behind the alternator. if you got studs, you'll see the threads of course lol
 
#7 ·
you tee a psi gauge on the upper degas hose and place the gauge where you can see it (taped to windshield etc ) then take it out an run it hard and watch the gauge for spikes

make sure your heater bypass valve if equipped is not stuck shut