Poor Heat in Both Front & Rear Units

[vivaster]

I have a 1998 expy 5.4, I also have luke warm air coming out of front and rear vents. Checked hoses and heater core hoses and upper were warm, not hot.

It is at the shop right now. They have changed t-stat and flush whole system. They flushed heater cores really well, forward and back flush. There was alot of junk in there. So far, the heater putting out better heat, about half of what it should be. Tomorrow, they will replace my waterpump.

I will post again when I check on it tomorrow

 

[vivaster]

I have also read in this forum that the t's are reduced in diameter. The hoses may be 1/2", but the t's are reduced to only 1/4". Some had cut those t's off and replaced with 1/2" copper t's. This increased their heat output.

I'm not saying this will fix your problem, but just a suggestion from someone elses post.

 

[Shinobi'sZ]

Thank you and I do agree that many don't bother to return to post results. Looking forward to your return.

Ok well I've been busy with work, but I managed to cut the heater hose coming off the water pump with the restrictor. The restrictor is about 3/8" diameter in a 5/8-3/4" hose so it is significant. The inside of the hose appeared to be a little rusty but was clear otherwise. I went ahead and spliced in a hose barb to get rid of the restrictor. At idle the front and rear were warm/hot but not as hot as it should be, and althogh the heatercore feed lines were too hot to grab for longer than a few seconds, the return lines were a little hotter than before but no where close to the feed lines.

Then I went for a drive which seems to be the real test. The rear heater maintained the heat, not hot enough to shut off, but signicantly warmer. The front almost instantly went cold when driving in the 39* weather so the front heatercore is not flowing enough fluid through it to overcome the cooler outside air.

Just to test pressure across the heatercores I also pinched off the front and rear heatercore feed lines one at a time to see if the increased pressure would help push more fluid through each heater core. It made no difference with the front.

Based on this I have ruled out the restrictor and waterpump as the culprit. The reason I rule out the waterpump, is simply because the heatercore in the rear has a longer run coming off the same T for both the feed and return lines. From a pumping perspective it should take more effort/time to pump fluid to the rear heatercore than the front as it is a longer run. Which tells me that there is a flow problem in the front heater core and the rear is clearer but not completely clear as it should blow hot to shut off after awhile driving.

I am going to replace the rear heatercore as it is easy to access and if I can at least get it to blow really hot, it will heat the cabin enough to keep everybody warm and I can get by without having to take off the dash to get to the front heatercore until the summer.

 

[RDEXPO02]

The biggest misconception is the feeling of the hoses to see if they are hot.

First, the factory OEM hoses are VERY well insulated, thick and beefy and keep the heat well within the hose. As I posted earlier in the thread I could hold the hose no problem for a min or so until it was just a tad bit uncomfortable.

Cutting the hose and replacing the first half of it with a foot of auto parts bought hose (to rule out restrictor) and you can't hold the auto parts part of the hose for more than 2 seconds. Because the auto parts hose is for crap and not insulated like the OEM hoses.

So that test just doesn't tell me anything.....

Here is what I am still trying to figure out......

1) How can BOTH front and rear units be having a problem at the same time? The only thing in common is the water flowing through the lines, and we know its hot.

2) Am I safe to assume that the water line has a tee in it and the front and rear units are in series somehow?. Is there a diagram of the piping on the DVD I bought or can someone draw it for me? If I blow in the hose with my mouth I get water coming out the other end so I don't have a clog right?

3) How can I have two bad blend doors one in the front unit, one in the rear unit?

4) Why do people on EBay, auto parts stores and other places say there is a heater line valve for my 2002 Expedition if there isn't one?

Sooo frustrated, but appreciate all the help thus far.... Just wish someone had the magic answer.....

Saving up to take it to ford for diagnosis or do a water pump myself if it gets above freezing long enough here.....

 

[bedrck46]

First I would say the being there is a tee in the hoses That the heater cores are in Parallel and not in series.

If they were in series then they would be fed to the first core and then to the second core and then a return line

I do agree with you and also wish there were some Magic Answer.

 

[vivaster]

So far the waterpump was replaced. Thermostat was replaced and a coolant flush was done with all new fluids. When theflush was done,y mechanic flushed the heater cores really well. I've got about half the heat from when it was working well. It is comfortable enough in about 35 degree outside temp. It doesn't get hot, just warm in truck.
MY only thought is overall coolant temps are being cooled too much. My truck's fan may be over-cooling the coolant. I will check the clutch on the fan and associated electronics controlling it

 

[Shinobi'sZ]

Ok well I've been busy with work, but I managed to cut the heater hose coming off the water pump with the restrictor. The restrictor is about 3/8" diameter in a 5/8-3/4" hose so it is significant. The inside of the hose appeared to be a little rusty but was clear otherwise. I went ahead and spliced in a hose barb to get rid of the restrictor. At idle the front and rear were warm/hot but not as hot as it should be, and althogh the heatercore feed lines were too hot to grab for longer than a few seconds, the return lines were a little hotter than before but no where close to the feed lines.

Then I went for a drive which seems to be the real test. The rear heater maintained the heat, not hot enough to shut off, but signicantly warmer. The front almost instantly went cold when driving in the 39* weather so the front heatercore is not flowing enough fluid through it to overcome the cooler outside air.

Just to test pressure across the heatercores I also pinched off the front and rear heatercore feed lines one at a time to see if the increased pressure would help push more fluid through each heater core. It made no difference with the front.

Based on this I have ruled out the restrictor and waterpump as the culprit. The reason I rule out the waterpump, is simply because the heatercore in the rear has a longer run coming off the same T for both the feed and return lines. From a pumping perspective it should take more effort/time to pump fluid to the rear heatercore than the front as it is a longer run. Which tells me that there is a flow problem in the front heater core and the rear is clearer but not completely clear as it should blow hot to shut off after awhile driving.

I am going to replace the rear heatercore as it is easy to access and if I can at least get it to blow really hot, it will heat the cabin enough to keep everybody warm and I can get by without having to take off the dash to get to the front heatercore until the summer.

Ok got a good update. There have been a few posts after mine with claims that the test might not work, but so far they have exactly as outlined.

This morning while driving to work I shut the front heat off because it was blowing cold air and I was just using the warm air from the rear to keep me warm. I went to pass some cars and when I did I heard water flowing threw the hoses in the firewall and out of curiosity I turned the wheel on the front air and warm air continued to blow, I heard the water moving sound for a a few more minutes and thought maybe the heatercore cleared out some because I took the restrictor out of the line.

During the day I thought about this video I saw on YouTube of some dude back flushing his heatercore with some CLR and thought to myself what the hell I might as well try it before taking out the heatercores.

I removed and cut the return, remember I already cut the send to the heatercore to take out the restrictor. I then blew out all of the coolant with an air hose out of the heatercores by forcing air threw the return and blowing out the send into a jug. I then poured the CLR down the return and the send. I let it stand for 10 mins then reverse flushed with water from a hose. A lot of crud filled the jug I was using to capture from the send. I then repeated the entire process, and reconnected the lines. I started the vehicle and turned on the front and rear heat.

I'm happy to report that the front heat got hot, hot enough that with the temp set to max 90* that I couldn't leave my hand over the vent without it eventually getting so hot that I he to move it away. The next test was to take it for a ride.

With the outside temps in the 40's the heater blew so hot that I eventually started to sweat, and I couldn't hold my hand over the vents without them getting too hot, I was able to turn the temp down to 75* and the heat was good inside.

So the flushing has bought me some time and I don't have to replace my heatercore right now. I know that it most likely is not 100% clear but I have really hot air blowing now whereas I didn't not last night.

If you have the conditions I described in my previous post, most likely your heatercores are starting to lose efficiency due to rust.

I highly recommend using the CLR back flush before removing and replacing the heatercores. You may get lucky and get a little more life out of them before having to replace.

BTW I put the restrictor back in place too.

 

[vivaster]

Thanks Shinobi, I will try that. Does anybody know if CLR is harmfull to the hoses?

 

[Shinobi'sZ]

Thanks Shinobi, I will try that. Does anybody know if CLR is harmfull to the hoses?

It's not harmful to the hoses at all. It only attacks rust, calcium, and lime chemically as an acid.

Here is something I should have mentioned. If a heatercore is rusted to the point that it is blocked, it is on its way out in the first place. I'm not sure if these heatercores are steel or aluminum, CLR will tarnish aluminum or dull it, so they recommend not using it on something like a polished aluminum wheel as it will burn it.

Anyway if the heatercore is rusted and you use CLR or Prestone Flush, it could possibly create a leak by removing/dissolving a rusty spot. I figured if this happened I would put in some BARs Stop Leak to seal it off, that could theoretically re-block a heatercore and result with no heat again. But it was a risk I was willing to take for two reasons, one to have heat and two to confirm the issue was blocked heatercores. That way whether I replace both heatercores myself or pay a shop to do it, I know what's wrong with my system.

For now I have very hot air blowing front and back to the point I have to turn the temp down even with the fan blowing on high. It could be that I continue to back flush with CLR every Winter until the heatercores start to leak and force me to replace. Besides the initial $$ I spent to have the shop diagnose, who by the way diagnosed correctly. I spent $20 for CLR and 2 5/8" heater hose repair kits from NAPA to fix my heat, vs. $1000-1200 or 10-12 hours of my time to pull both heatercores out and install new ones to get the same result. Which is the ultimate fix.

@Viv- I want to point out something that I just read in your post. A mechanic or shop simply replacing the coolant with new coolant is what most shops will consider a coolant flush. I called a shop and asked them if they would flush my system and they're response to me of what was involved was simply to remove and replace coolant. That is not the same as a back flush. A back flush involves pushing fluid in reverse through the system to dislodge any clogging that has accumulated along the top of the fins of the core thus blowing back out the way they came in. The CLR melts those particles, and the back flush pushes them back out vs. pushing the contamination through the core and into the engine and radiator, waterpump, thermostat, etc.

 

[vivaster]

Thank you shinobi for your response. I will keep the possible leak problem in mind. I did have the shop flush the cores. They pinched off the lines individually and forward & back flushed each one until nothing came out of them. I took my truck to a radiator shop who specialized just in this. Right now my truck get enough warm air to keep it comfortable in the cabin. I would say it gets to around 70 degrees inside the cabin after half an hour on a 35 degree day. Fortunately our expedition is our extra vehicle that gets used mainly in the summer to pull our popup trailer for camping or for when one of our other vehicles are in a shop.

I am contempt right now with my truck. I will try the CLR flush when I start losing heat. I asked about the hoses & CLR because others on here have claimed to sprung leaks in their hoses after using the prestone flush, sometimes as early as 3 months.