E-350 heat problems... And it's damn cold!

Hello-
I have a 1983 Ford Econoline 350 1-ton cargo van and I'm having some issues getting heat into the cab. I'm only getting lukewarm air (possibly 55 or 65 degrees F?), but I'm worried about traveling in
snow/ice where keeping the windshield will be critical.
I've already investigated the usual suspects:
- The heater core seemed to have good flow when I flushed it out. Both heater hoses (send and return) seem to be hot to the touch, but one (I'm guessing the send line) is much more firmer than the other. Not sure why...
- I've replaced the thermostat with a brand new one.
- I'm getting good airflow from the blower motor into the cab, just not HOT air.
I've tried putting cardboard over the grill, and I've even tried blocking off a majority of the radiator (with cardboard) just to see if I could get the engine to run a bit hotter. Neither of these worked. The temperature gauge seems to only creep (barely) into the NORMAL range, even under heavy loads.
Is it possible that there is a duct leak? Or something clogging the duct?
Not sure what to do at this point...
I'm open to any suggestions!
Thanks (in advance)
Kevin
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Have two ideas. R U sure about the t-stat? Maybe you installed the wrong temp range. For good heater performance it should be a 190 stat. Second: Maybe the radiator cap is bad/weak.
Even if there was a duct leak, you'd still feel heat in the cab, since all the duct work is inside the cab.
If both the supply and the return hoses feel about the same temp, you should be getting circulation thru the core. If one feels cooler than the other, it may be stopped up.
One hose feeling 'hard' gets me to wondering if there might be a problem with it. You might try replacing the hoses....cheap insurance.
Hope this helps!
Dave S(Texas)
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Look into that send line issue. Are you sure the heater core isn't clogged?

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Diesel or gas?

Did you actually measure the temperature, or is it a swag by using your hand?

Does it keep it clear now?

Means nothing, the heater core has a by-pass in the event it gets plugged. Measure the temperature at the heater core it self. That way you will know if the heater core is getting hot or not. If it does not get hot, well that should be self explanatory.

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Answers to all of your questions:
1. I replaced the T-stat with the factory value: 195F. The one that I removed from the truck was also rated for 195F.
2. Both hoses felt hot to the touch. I didn't actually measure them with a thermometer, but they were definitely hot.
3. Not sure on the heater core being clogged, when I tried flushing it out, it seemed to have a good flow of water, but as Thomas suggested, the flow might have been right through the bypass. I didn't have a lot of time to diagnose the heater core much further than that, as living in Maine (and not having a garage) makes for difficult outdoor working conditions.
4. This particular E-350 runs on gas: 351W, V8.
5. Luckily, I haven't had to find out (yet) if the minimal heat would keep the windshield clear in the event of snow/ice... As you can imagine, it's not only a comfort issue, but a major safety issue as well!
Hope the additional info helps!
Thanks again!
Kevin
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sundog snipped-for-privacy@yahoo.com (Kevin J. Ostrowski) wrote in

Look into heater box issues, like a broken blend door. My '83 LTD had the same problem. I found that the blend door had that weak plastic flex kind of hinge on it and it had broken completely off. I fixed it with a real metal hinge and some sheet metal screws.
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