Ok, here ya go...

I have been on here before along with others complaining of the no-heat, little-heat problem for years. It has stumped me. Front & rear AC/ Heat setup. Good water pump, good heater cores, good thermostat, good blend door actuating servos, good servo potentiometers, good blend door spindles, good fans, etc. Still no heat or just a smidget on low. Turn up the fan and no heat. Sometimes, more heat than other times, but usually very little.

185,000 miles on the clock.

I *know* some of you have this same problem. Sometimes it is a blend door or actuator or control. Sometimes it is other things, but this time it was something completely new to me and the first time I'd ever seen anything like it.

The problem is that on the supply heater hose (stock hose in my 99 and still good) coming from a tube at the rear of the block (on the passenger side), there is a FLOW RESTRICTOR in the hose. You can feel it inside the hose if you run your hand over it. I thought it was some type of check valve, but it is just a small device with a plate and hole in the middle.

For whatever purpose this is in there for, as the vehicle ages, it is possible for some small flecks of cast iron to come off in the cooling system. The ID on the heater hose is 1/2". The opening inside the restrictor is 1/4". It is *very* easy for that orifice to get clogged or to be partially blocked, resulting in little or no flow.

When you consider that (in my vehicle), the plumbing travel is about 36' in total, then I'd think you really want and need as much flow as possible.

My son and I clamped the hose on either side of the restrictor and cut it out. We then reconnected the hose with a piece of 1/2" copper pipe and double-clamped each side.

Viola! Works like new. As a matter of fact, it works so well that I had to make the statement that I hadn't made in years; "It's too hot in here, let's turn down the heat."

So, if you have your family wrapped in blankets in your vehicle like I did, this could well be the problem. I am just really, really disappointed that it took me years to find it when it was really something pretty simple.

I hope your final solution is as easy as this was! If it was, please add it to this thread and maybe it will get a sticky.

 

good to know...need to do mine

 

The funny thing is that if you put "ford expedition heater hose flow restrictor" into google, you will find a lot of chatter on this. That could have saved me some time, but most people with look for "no heat" or "poor heat", etc.

I read through what google found and there is some fact and some nonsense. The fact is that without the restrictor, the heat will increase with engine RPM as the engine outputs more heat and flows more coolant through the cores. I guess the restrictor "throttles" or "averages" that change so it is not so obvious, but it is in-fact, going to slow down the flow through the cores and limit the amount of available heat to pull from the liquid (depending on the efficiency of the heat-transfer through the core).

The nonsense part is that someone claimed it blows out the seams on the heater cores. The restrictor limits flow, not pressure. Additionally, in a system like mine, there are 2 "T" fittings which have small diameter openings (splitting off to supply and return for each of the 2 heater cores). Given the 36' (probably more like 40') of piping in a dual system, that 1/2" ID coming into the system has to flow through 2 exchangers all the time (with the heater control valve open in engines that have that - 4.6 does not). I don't know what the core ID is for the actual heater core tubing, but the connections are 1/2", so to get 100% simultaneous flow (volume movement) through two 1/2" cores, we'd need a 1" feed. I am not a hydraulic engineer, but this seems right to me. It also seems to me that blowing out seams on a heater core comes more from overheating and high pressure, than a less-than-100% flow. This may be different in a system with only the front core, but again, I am not a hydraulic engineer.

If anyone is concerned about this, then I guess they can put a piece of old hose around the supply hose and clamp that to squeeze down the diameter a bit, but I really don't think it is necessary. I guess they could also drill out the orifice in the restrictor to a slightly larger diameter and reinstall it. I'm not sure if this would deal with the clogging or not, but there is absolutely no doubt that once there is debris in the system, it will get behind this restrictor's orifice and block it, killing your heat output.

Who knows, perhaps this restrictor allows more sediment to build up in the cores by killing the flushing effect of a stronger flow?

At 185k on the clock, I'm just happy that we have heat again.

 

Needs to be featured on Jeopardy, with a Ford engineer starting the sentence with "What is..."

Excellent work on finding the problem. I'm more of the 87-96 OBS forum, wish that this was the solution for those who ask about no heat there.

 

Good job finding the issue. FYI, the restrictor is necessary to force more coolant to the front heater core because of the driver's comfort, and because of the necessity of the defrosters.

 

That would make sense, except for one thing...

The restrictor is in the supply to both the front and rear cores. For what you describe (which again, makes perfectly good sense), it would have to be in the line for the rear core.

Strange...

 

That's a new one on me. I always thought it was just in the rear heater core line. Oh well, I learn something new all the time.

 

Had this problem which developed slowly over one year. Both intake and outlet heater hoses felt cold. Problem is access to the hoses from the engine side. I found it worth the ten minutes to disconnect all the plugs on the power hub, and pull them to the side. This gives easy access to cut the hoses and to use a garden hose with a barb fitting. When water is applied to the inlet side it just would not flow with some 40 psi water pressure, but when the garden hose was applied to outlet side, slowly a trickle of water run and then finally with a lot of junk the water flow easily! Finally, install a couple of brass barb fitting to reconnect the cut heater hose.



This is the hoses reconnected. Note that the power hub is not in the way!





Here is the power hub disconnected and moved to the side! The big connectors easily separate by unscrewing the bolt between each half.





Here is the power hub with the cables hiding the water heater hoses!

 

That was a pretty well blocked heater core.