The Stovebolt Site Forums The Shop Area General Truck Talk cold weather affecting heater / thermostat??

My truck, '61 1/2 ton 235, has cold weather trouble. The heater will not get hot, today it was 8 degrees farenheit, and I am starting to think that maybe I should change my thermostat to allow my engine to run hotter, my dad seems to remember doing this in the old days? I know the old cardboard in front of the radiator trick, but would changing the thermostat have the same effect? I am wondering which one of these is the better solution. If it is the thermostat what temperature one should I use? ANy feedback would be greatly appreciated.

get a 185 thermostat and potato bags in front of the rad - cardboard's not as good - works fine for me - makes life nicer too if you get a convection style block heater so the heater is blowin warm air as soon as ya fire it up in the morning - set it on a timer to come on an hour before ya go out in the am

Bill

There is no place I can think of in Washington state (I grew up there) that is cold enough for the radiator to overcool the engine. What is the temperature gauge reading? Is there water circulating through the radiator?

Thermostats fail stuck open usually, so change it, and make sure the coolant is full. It may also help to drill a small hole in the thermostat to help air bleed out of the system.

I'm working on a big bolt, but I also have a 57 Buick. I had a similar problem for years with it. In the summer I would be ok, but in winter the thermostat would not open until the water in the block was too hot, then when it did open the water would circulate through the radiator, and immediately the thermostat would close and the cycle would start over again. I think this was because I was using a thermostat with an opening temperature that was too high. It is possible the same thing would happen to your bolt if you increase the thermostat temperature too much.

I finally gave up, took the thermostat out completely. In the summer the car runs fine. It gets up to normal operating temperature just fine without a thermostat, and in winter I put a piece of cardboard over part of the radiator, and everything works like a charm. I'm sure this is not the way it should be done, but it works, so I'm happy. Allen

go for a 195deg thermostat.You can reverse the heater hoses if easy.This reverses the flow and flushes the heater core.Then next year flip the heater hoses again.Cardboard is fine for a quicky,but do it right.Your engine runs best around 195 deg With the 195 you'll have heat in a few miles

Make sure there is water going thru the heater. Are you sure your control valve is working? Good luck.

this morning i went out and started the truck with the rad cap off and watched. it took about 10 minutes for the water to start circulating...this seems like a long time to me. i do not have a temp gauge, i know shame on me. i heard 2 numbers 185 and 195...what is stock? i know that it has a good thermostat because i put a new one in a few years back...so i think it is ok. i guess i am going to have to change the termostat. reversing the flow by swapping the hoses sounds interesting. would those be the red hoses that run thrugh the firewall? so it sounds like thermostat, thanks guys.

Couple of things I have learned through the years.

First, either your heater is partially plugged, the heat control is blocked, or your thermostat is stuck open. Check the stat first by opening the radiator. If the engine's cold and coolant is moving, the stat is stuck open.

If you replace your stat, it is not recommended to go over 180* on the 235. The head doesn't like the extra heat and the higher temp makes it prone to cracking and warpage. Learned that after taking my head in the last time, machinist told me to go with 160* stat.

The 61 had a far better heater than the AD series, and would keep the cab warm below zero. Another thing to check is air leaks in the cab.

Cardboard in front of the radiator will usually help, but keep a close eye on the temp gauge on warm days.

I can see the Ad for those trucks now...."Even comes equipped with cardboard on the radiator at NO extra charge".
Friction causes heat. If the engine is worn bad it is going to take longer to heat up the coolant.
Engines were designned to operate at a set temperature..the thermostat controls that providing that the rest of the cooling system is in working order.
Reversing the heater hoses may cause the heater to not work properly too. They are designed to flow in one direction.

Heater hose connections...made a difference in my 1960 Windsor that went back on the road in April...when cold weather arrived, I only had heat when running slow around town...as soon as I got up on the highway, heater blew cold...engine temp was normal...coolant level oaky, etc.

I took a look in the shop manual and realized that I had hooked the heater hoses up backwards...(hey, a "loop" is a "loop", right ?)

I reversed the hoses and now have plenty of heat.


With Stovebolts, start by making sure the stat is working correctly. A 180 deg F stat is a good place to start.

Next, make sure that water is flowing through the core at a reasonable rate...with the engine warm and running, both heater hoses should feel warm to hot.

Make sure the fresh-air side of the heater core isn't choked with leaves and other compost (or rodent nests)from the fresh-air intake.

If you have good engine temp. good water flow through the core, and good air-flow through the core, then make sure that the hot air isn't being expelled through the holes for the heater-core tubes or other opportunities to escape before it gets to the heater/deforster outlets...

If a piece of cardboard in front of the radiator "magically" gives you heat out of the heater, that's an almost certain sign that your t-stat is bad...

Also, the suggestion about closing-up any holes in the coachwork is a good one...missing weatherstrip from doors or holes here and there can allow drafts that exceed the heater's capacity...

Don't cook your motor trying to get heat in the cab though...I managed to overheat my '72 a few times driving with cardboard in front of the rad !

I just put a new heater core in mine (a 64) when I bought it because of the mouse smell. The new one weighed half as much as my old one due to the clogging. Even this morning at -15 degrees, I had to turn the heat down about halfway to work. Don't try flushing to old core, it will put out marginal heat at best compared to a new one. Besides, your 61 is probably the easiest truck there is to put a new core in,
Scott