If the degas bottle had crap in it I wonder what is in the radiator.

 

jhl3,

It is possible that the plugging of the heater core could raise coolant temps slightly, but the rise in EOT could also be due to a hotter a/c condenser temp. The heated air from the a/c condenser is passing over the other heat exchangers, causing their temps to also increase slightly. I always noticed a rise in EOT and EGTs with the a/c "on", especially at idle and low speeds. This temp increase should not cause an overheat condition, unless their is another problem that is making the cooling system insufficient. If that were the case, everyone with the Ranger mod, or an Excursion, would be having this problem.
I don't have a diagram of the engine coolant flow, but I do know it does flow "out" of the cylinder head connection "to" the heater core and "returns" back "in" at the tube on the water pump.

 

Thank you for your reply. I agree that it is not a singular issue with the heater core being "possibly" plugged and if my question implied that then that is my fault for not being more specific.

I use "only" the Ranger mod that provides a return path-utilizes both heater core hoses- to the water pump due to a concern, possibly unwarranted, that not doing so-using the Ranger mod that utilizes the single hose thus blocking the return path- may provide insufficient cooling of the PS head.

So, in the event that the heater core does become blocked, with or without the mod, is there a return path inside the PS head/block similar to the DS head/block for the water to return to the pump? If so, this would rule out the heater core as a source entirely and would mean that the normal path to the heater core would be redundant, in some respects, and also would be the path of least resistance by default or else it would not work well.

Or am I missing something?

 

Ok, today i went and purchased a new fan clutch. Pulled the one on the truck, and compared the amount of force needed to turn shaft while holding the clutch. Both felt identical. I dont think its the fan clutch. I proceeded to drain system again. I pulled the radiator. Flush with water hose. Flipped upside and flushed first to see if any debris would come out. I did not notice any debris or trash exit the radiator. I put my hand over spout and allowed it fill from the hose on top. When it was full i removed my hand and the whole thing dumped in less than 5 seconds. I dont think its the radiator. I refilled system same as before with the thermostat housing off and allowed air to purge while filling. Once no more air burping I installed the t-stat housing WITHOUT the t-stat. I connected all hoses and filled system. I then went for the same drive i did on friday (about 11-12 miles). Inside the cab all indications are that everything is A-OK. Temp gauge in normal range, maybe a little lower. Upon returning home i popped the hood and sure enough the same thing had occurred. Coolant puked out of the cap, percolating noises in the hose from t-stat to radiator and from radiator to degas bottle. System is under pressure because as i unscrew the cap i can hear the hissing and can see the level rise in the bottle and close off before it spews out.

So now im really stumped. With the thermostat out it does the same as with it in. Pukes out cap, boiling in hoses and top of radiator. I am almost thinking that it is not circulating at all. Like the pump isnt pumping. But I installed a brand new pump just last week. Well, like i mentioned, i bought the pump from Clay about 2 yrs ago, sitting on the shelf all this time in its box until last week. What are the chances that a new pump out the box is toast? But thats the direction I am now leaning like the fluids arent circulating and is overheating and only circulating by thermal cycling. But why does the gauge not indicate as such? Its an enigma for sure....

 

is the degas bottle bubbling while idling with the cap off?
will it build excess pressure just sitting and idling?
if it is, that would indicate combustion gasses in the cooling system ( head gasket)

 

Last week me and a coworker idled it in parking lot and held hand over the bottle neck checking for that very thing. After high idling for about 8-10 mins we could not determine any pressure increase. On Friday, before i took my test drive, i let it idle for about 10 min while in High Idle tune to warm it up a bit. I did not notice, but then again i wasnt looking for that. Will try again at some point and look for that.

 

I could not find a coolant flow diagram for the 7.3 PSD, but I did find this one for a 7.3 IDI. The flow path is similar. The coolant from the lower part of the radiator is circulated thru the block and oil cooler by the water pump and up into the heads, returning back out the front of the heads to a passage in the front of the block leading to the timing cover which connects to the thermostat housing/outlet on the water pump and returns to the upper side of radiator.
You'll have to use your imagination a bit, but I hope it helps you with my explanation.

The heater core and hoses add a flow path similar to the addition of a coolant filter. IIRC, all Excursions with the factory installed heater valve are of the non bypass type. Ford must have determined a bypass was not necessary.

 

The factory Ford dash gauge plain old sucks. It's more of a dummy light with a needle. It stays right in the middle from about 160-235. On my truck, when coolant temp reaches 235 it moves into the red pretty fast.

Get a laser temp gun and shoot the t-stat housing during some of these runs to verify.

 

Check the routing of your belt to make sure that the water pump is turning in the correct direction. If you don't have a diagram under the hood let us know. Additionally, I have read that for the coolant to circulate properly throughout the system that the thermostat has to be in place...could be an internet rumor though..something to do with the tall thermostat(correct one) as opposed to the short one(incorrect).

 

Thank you for your time and effort. I am working on it....

You are correct in that the Excursions have the non bypass type.

 

What are your engine oil temperatures looking like?

 

There is an internal coolant bypass within the water pump housing. The stem on the bottom of the thermostat closes this passage to allow for full circulation when it fully opens. Having a thermostat, or the right one, is important for this very reason.

 

Perhaps visit a shop that performs exhaust emission testing and see if they will "sniff" the degas jug for hydrocarbons? I know the testing machines are extremely sensitive at detecting hydrocarbons and have been told that any reading above 50PPM is indicative of gases entering cooling system. Just a thought for diagnosing.

 

Im pretty sure that the belt is right, its been my experience that there is pretty much only one way it can go unless someone can say otherwise. But I will double check against the diagram just to make sure. I don't know oil temps as I don't have a gauge or any scan tool hooked up.


But, this morning I drove it to work because of threat of rain and my only other transportation options aren't conducive to heavy down pours (jeep, motorcycle). Anyway, still WITHOUT the t-stat, I drove it nice and easy, no hard accelerations or high speeds, never got over 60. Drove fine. I get to work, it did NOT puke out of the cap this time, but I can still hear some slight gurgling/percolating in the top radiator hose, not near as much as before, but its there. But here is another piece of info, for grins and giggles I turned the heater on. Nothing. No heat. None. With heater turned wide open and fan wide open all it does is circulate the inside cabin air. So obviously either it is plugged, or the supply going to it is plugged. I would lean against the heater core being plugged being the issue because that is essentially what the shutoff valve is for. The truck can obviously run without the heater core loop. But if the supply going to the heater core is plugged, well that could be something entirely different. And if I understand correctly, the flow comes from block to the core, and then the core back to water pump. If the core supply is blocked, then that must mean there is blockage inside the block?


My next action is to remove heater hose from top of water pump. Insert a small hose with bolt and hose clamp to block it back off. Hold that heater hose to the side of hood, crank truck and see if I am getting circulation thru the core. It should just pour out of the hose I would think. Of course would not do this long, just to verify if circulating. Which I don't think it is because of the no heat. If it was winter I would be screwed with no heat in the cab.

 

Thank you for the clarification.