So i got this 03 E150 cargo van with the 4.6 with 75k miles.
It didnt have heat well, then after like 30 miles it started to over heat. We pulled over let it cool down and then bought antifreeze cause it was low. It took almost a whole gallon. We made note that there was a used thermostat in the center console. Got back to the shop and checked to make sure there was a thermostat in it, there appears to be a new one in it. Topped off coolant. Now it pukes and heat doesnt work all the time.

It seems like the air just doesnt stop coming. Classic sign of head gasket or cracked head right? Used an OEM block tester and the color of the fluid just turned very light blue but certainly not yellow or green.

I dont know what to do or where to start now. Any ideas?

Also, i should note oil isnt milky and coolant doesnt appear to be oily.

 

If you still have the block tester, Double check the fluid by letting it suck some in some exhaust fumes at the tail pipe.. I have read that the fluid has around a 1 year shelf life and needs to be stored away from light.. You never know how long it has been on the shelf at the parts store.. I had checked an engine about 1.5 years ago stored the extra fluid in a cabinet in the house. I used it a couple of weeks ago and it did not change color at the radiator. When I checked it at the tail pipe, it turned clear instead of yellow.. 1.5 years ago when I first bought the fluid, it did turn yellow when I checked at the tail pipe.. So you might want to double check that fluid just to be sure it is good..

Make sure the antifreeze is not filled to the top of the radiator so it wont suck coolant into the tester..

One of the testers I got from the parts store was stopped up and I had to return it for another one...

Another thing I noticed on my van is that I was parked on a slight angle with the upper hose on the high side. I kept getting a few air bubbles because the coolant level would raise and lower slightly trapping air in the upper side of the radiator..

Here is an interesting home made tool for bleeding the system in case it is just air

I have used this kit before and it worked pretty good.
NAPA AUTO PARTS

Hopefully it is just air trapped in the system from being hot...

I have had a thermostat go bad within a couple of weeks and had to replace it.. Also make sure the PO installed it the thermostat correct direction.. Spring side towards the engine and pointing side towards radiator..

How long have you had the van and how many miles have you put on it? If you just bought it, i would wonder why they replaced the thermostat to start with..

 

I will definitely do the tail pipe test! I got it from an auction. I get all my vehicles there. I made sure i installed the thermostat correctly when i put it back together. I bought the test tool, i still have it. Its not plugged up, but as the air pushes into the system the coolant does rise. I try to get it low enough and off the tester before the coolant hits it.

 

Did a tail pipe test for about 30 seconds. It was ever so clear with a hint of yellow only noticeable with a white background behind it. Um maybe i should try the coolant one again. I dont know. I figured the color would have showed up almost immediately seeing how the tail pipe on a cold start would have a lot of hydrocarbons.

 

I did my test from the time I started the engine cold and all the way till the engine got up to temp, and then a bit more... The fluid I used did not change colors at all... Some people recommend to reve the engine up to around 2500 rpm's, others don't.
I believe you said the blue did get a little lighter in color when you first checked the radiator, I would defiantly repeat the test.. If you lower the coolant level a little in the radiator, it also gives it more room to collect the gasses if you have a leak.

 

I cant do the test long enough. Coolant gets up into it too soon (before its warmed up)
I took the upper rad hose off before the test to see if it was full and it wasnt. Nothing came out and the bottle was empty.
I took off the upper rad hose while it was running and it was just streaming out of the rad. I feel like it should have been gushing but maybe its really low on coolant?
I also flushed the front heater core to be sure it wasnt clogged. no change.

I was told to change the thermostat so im gonna put a new one in (current appears new but might not be)

Could a bad water pump do this?

 

my two vans are 88 and 85 with 302's in them and i am not as familiar with the 4.6. I do have a 4.6 in my town car but never had any issues with it other then the oil filter adapter gasket leaking.. I assume since it is basically a small V8, it should be similar to a 302...
My 4.6 has a aluminum intake i have heard that some have a plastic, or composite intake and sometimes they crack, but you say there are no leaks and the oil looks good, and no white smoke...
If the thermostat is easy to get to, maybe try leaving the thermostat out and fill it with water to see how it does...
I am not sure if there is a factory bleeding procedure on the 03 4.6 but something that might help while checking the system is to leave the stat out,, take the upper hose loose from the radiator and fill the engine with water from the upper hose. With the upper hose still off, fill the radiator Take one of the heater lines off and flush it with water till you are pretty sure there is no air in the heater core and quickly put the line back on so it doesn't suck air back in as the heater core may be higher then the engine.. Double check that the upper hose is full and reconnect it to the radiator and fill the radiator and resavor.. Run it with the cap off a little and see whit happens.. It may just be air pockets from where it overheated before...
With the stat out it should not get hot enough to blow out steam unless there were trapped air pockets...
I doubt the water pump is bad... normally they will leak out the weep hole. I have heard of them rusting the impellers if they sat for a long time and the impeller coming lose on come pumps but it is very unlikely..

Before you do any of the above, You might want to take the bottom hose off and run a water hose in the top of the radiator to see what the flow looks like going through the radiator.. That wont really tell you if the radiator is good or not, but will tell you if it is badly clogged. You could also hold your hand over the lower hose opening on the radiator to block it off. Once it is full, take your hand off and see how the water flows out...

Maybe some of this will help... I wouldn't jump right to the head gasket being bad yet...

Also make sure your new thermostat has a small hole in the flange and that that hole is installed up at the top, 12:00 position. Mine does not have one but that helps bleed air out of the block before the T stat opens.. Some people drill a small hole in them if they don't already have one..

 

hole is there in t stat. its installed correctly. Im going to take your advice and see how the flow is with the rad, then go to the next step with taking the t stat out. Ill update this eventually as its not top priority right now.