We just finished a 3500 mile road trip. About 2/3 of it crawling around in 4 high in the snow and ice on I-40. That was fun. We went to NC and back. Anyway, on cold startups when it was below zero out in the mountains it started just fine but I still got some leakage out of my front oil cooler gasket. Nothing bad enough to hit the ground though and it went away quick enough as it warmed up.
I'd let it idle about 1300 rpm for half an hour before we left each time and woke up the rest of the hotel guests about 6 am every morning. The temp gauge would still barely move before we got back on the road though. The highest temp I could get in the cab when it was below freezing out was in th e60's. Once it got above 32 outside I could get it closer to 80. That wasn't nice. I had the whole front of my condenser covered with 2 layers of cardboard and that was covered in ice for most of the trip. I also wrapped the heater hoses and coolant filter with black pipe insulation. It was a long cold trip. Lots of cars and trucks in the ditch. Especially in the mountain pass between NC and Tn. And in Arkansas. Those arkansas people are just stupid.
My mileage was decent. 18-20 mostly. The fuel in my big tank in the bed gelled up a bunch of times even with a double dose of howes crap in it. That was all we could find at the truck stops out that way. Going east I had power service in it and it never gelled.

 

I had a 94 one time and it would not warm the cab with the heater running full out.After alot of checking and wonderring I finally took the dash apart and found a ink pen had went into a top vent.It was lodged in a trap door for the heater so it would not shut the cold air out all the way.Got it out of there and the heater worked great after that.

 

You must have aproblem with either your thermostat or your heater core. I've driven mine slow like that in -30 and once the engine temp comes up to normal ( which does take a while ) the heater will run you out of the cab. I did have a problem with mine last winter it just wouldnt produce any heat. What I eventually found was the heater core was plugged. I blamed the plugging on the antifreeze I had been using (Fleetgard) and the fact that the truck had basically sat unused for almost 6 years. The antifreeze had seperated and settled forming an almost rock like substance in the bottom of the radiator overflow bottle. When I removed the heater core I found the same substance. I used Permatex radiator cleaner straight out of the bottle in the heater core. I positioned the core so I could pour the cleaner in until it was full. It bubbled and cooked for probably 1/2 hour boiling all that crap out of there. I then flushed the core with a garden hose and pressure tested it. After reinstalling it I thourogly flushed the entire cooling system as well using the Permatex ( at a stronger rate than shown on the bottle) Refilled the cooling system and over a year later the heater is still working excellent. I dont know why the Fleetgard coolant settled and set up like concrete like it did other than from the truck just sitting unused but, I won't use it again.............

 

I agree there must be an issue somewhere. Mine when I drive it when its zero out does of course take a while to warm up but once it does I have to turn the heater down as it gets too warm. I don't drive it much in the winter but that is the case. I have a 195 t-stat fwiw.

I don't know what to tell you for sure though as I remember you've done a bunch of stuff already to your cooling system. Maybe one of these other guys ideas will work for you.

 

My entire cooling system is brand new except for the heater core but it's not plugged up. I put on a coolant filter earlier last year too and changed the filter right before we left just in case. The engine gets up to about 190-200, the thermostat opens then it settles out about 120-150 running down the road. The thermostat has got to be nearly or fully closed doing that. The heater hoses are running the same temp roughly as the coolant gauge. The one out of the heater core is about 10 degrees cooler. So it's getting some heat transfer. Just not enough. Oh and we took the cowl off a few weeks ago and cleaned all the leaves and dead critters out of it and hosed out the core fins through the fan hole.
The thermostat is a new motorcraft one and is the 4th one I tried in a little over a month. I tried the 203 too. It was worse. I guess this huge radiator just works too good. Maybe I can rig some bypass valves on the upper and lower hose and run a little bit of coolant through a transmission cooler out in the brush guard for winter time. hahaha

I'll go check that blend door today. Ya never know what could get into there with kids riding in it. Last time was a banana peel. I have no idea!

No seriously, My old farmall has shutters on the radiator for running in the winter. It's a distillate engine and needs to be warm enough to light it. I usually use diesel fuel these days and start it on gas. I love that engine!!!!!!!! I'm drawing up some plans for shutters on the front of my radiator because this is about ridiculous!

 

Have you tried taking the fan off ?...

 

yeah I did when I had the 203 in it but then the darn thing was getting up to 220 or so before the thermostat would open so I put the fan back on. It still did it. I didn't take it back off again when I put the ford thermostat in it but the fan is just barely turning in these temps. I could stop it with my finger, well someone elses finger, if I wanted to. It's really not pulling much.

 

Glad your trip went "ditch free".

You may wanna try bypassing the coolant filter. Assuming you used 3/8" fitting, its nominal cross section is ~ 1/3 that of the 5/8" line. That's enough to reduce the flow significantly and may be why you can't get more heat out of the core. If you are willing to try it, I'd suggest taking some temp measurements on the inlet and outlet hoses, along with the ambient air temp and the engine coolant temps, to verify the findings.

I had a similar issue with the furnace in the house years ago, when we first moved in. Turned out the furnace was producing its rated BTU value; it just wasn't transferring it to the house because the return air system was grossly restricted. Found the PO's heating bills from past years and guessing they set the thermostat sanely, fixing the return system reduced the oil burnt by a factor of 3.

 

You definitely have issues. To start with operating temp is way too low. You either have the wrong stat for the water pump you are running. Either a long stem in a short stem WP or a Short stem in a long stem WP. Other than at extended idle my operating temp is a rock solid at 200-205 with a 203 stat. Once its warmed up the temps are there no matter outside temps -20-100F. Only after 10 minutes or more idle time will the temps drop. But under power there is no fluctuation of the operating temps.

Then you have a heater issue. Plugged air or coolant flow. My truck has 280K all original cooling system other than a WP and 203 stat and I can cook myself out of the cab. Saturday I did. I was trying to get the floor dried out so the heater was full hot and the windows were down and I will still too hot.

 

I believe 94-95 needs the short stem if you have original water pump..
This is the long stem for the 96-97 with Ford water pump.



Actually the picture above is a 203* stat.

 

Same here , 3 year old 203 , it'll cook you out ...

 

I have a new 97 pump and long stem motorcraft thermostat in it now. I had the 203, a murray, stant and napa brand one too but all of them fluctuated badly from running down the road to coming to a stop at a light. The temp would just constantly go up and down. This one holds almost perfect 200 if I put the camper on or I'm pulling the horse trailer but not just running empty right now in these temps.

I'm going to put some t fittings in the lines going to the filter and run it on bypass. I'm sure that will help some but I'm not sure how much. The temp is still low when it's below freezing.
Remember I have the older big metal radiator. It had a 4 row originally and I just replaced it and found out they gave me a 3 row. When I got concerned about it not cooling enough for all the weight we haul in the summer I called the mfr to gripe and they assured me this one is more efficient than original due to closer fin spacing and bigger tubes. Yeah they weren't kidding!

 

Yeah, you have issues.

As others have stated, my 95 will absolutely cook you in 5-7 miles in -20 to 0 weather after a 10-minute warm up session.

In my opinion, Ford finally figured out how to make a heater by the late 80's. I have had countless 70's era F-series trucks...talk about never getting warm in the cab!

 

Well, thats good to know about the radiator.

I have the same issue as you.
My truck will not warm up until I drive for 30 mins, Then if i throw the climate controls on high, you'll get cold air eventually.

Our trucks just cool to damn well.
But I tell you, when its putting out hot air, it puts out hot air.

 

welcome to the real world son.