Hi all.. I have a question. I recently replaced my cooling system with all new components. 77 F150 400cid Auto.

New Radiator is the larger one, 3 row copper core.
New FlowKooler Hi-Flow Water pump.
New Track Boss 195 degree Thermostat.
New Temp Sending unit. Also my fan is original not a clutch fan. Runs all the time.

My temp gauge barely goes above the "T" in TEMP so just past the second mark. I can tell that the Thermostat is working properly and is the 3rd Thermostat I've installed.
Thought I was dealing with faulty thermostats out of the box but they all have exhibited the same. Bottom Radiator hose is cool to the touch.

I'm coming to the conclusion that now its just too damn efficient at cooling.

So I was wondering if I should/could put some cardboard in front of the Radiator to get the temps up.
Does that work? I've seen this done on large Semi trucks but was wondering if anyone has had to do this on an older F150?
Probably not necessary in the summer but come winter I think I'll want some heat in the cabin. I live in Colorado.
If I do this is there a preferred way to position the cardboard and or how much space to block... etc..

 

I would install a good aftermarket coolant temp gauge, before doing anything that would raise temp.

 

I live in central Canada where winter temps routinely drop well below -20F for weeks at a time. Over the years I have owned several older vehicles that wouldn't warm up enough in the winter to keep the interior temperature comfortable or keep the windows clear. Cardboard in front of the radiator works well. What most "old-timers" did in cold weather was cut a piece of cardboard large enough to cover the front of the radiator. It doesn't have to be done with much precision. Then cut a round hole in the centre of the cardboard--maybe 6-8 inches in diameter. If the engine runs a little too hot, then increase the size of the hole. Be careful on warmer days, because the engine will begin to overheat if there is not enough airflow through the radiator (obvious!). If you are using the cardboard trick in less severe temperatures then yes, there is something wrong with your gauge or thermostat.

 

Shoot your thermostat housing with a heat gun and see what it says. factory gauges are not much better than a good guess.

 

Thanks Red Mercury. I would never have tried to do it that way but it makes since.

 

I've done that. Love that tool! On the housing I get between 135 to 150 when its warmed up.

 

Seems like the thermostat should not even be close to opening at that point. You say it is, but is that based on flow you can see in the filler neck, or maybe the temperature of the upper hose warming up all of a sudden?

I know we don't have to put the little disc reducer thingies in our engines like the Cleveland owners did, but are you sure at least you're getting the proper special type of thermostat for the 335 series engines? I forget the exact differences, but if you're not sure someone here will now how to describe it.
Being that you've had multiples, I'm assuming you know all about the special needs for our thermostats, but wanted to make sure. Especially since running too cool is such an odd complaint around here sometimes!
More often it's "why can't I cool down my engine here in Anchorage in the winter?" type of questions.

But speaking of cardboard, while I never had to use it with my 400 and that same radiator, I do have to do something with my Bronco now that I've got a triple-bypass radiator in it. Hardly warms up now.
Mild climate, but I would still not have expected this to over-cool my engine. Broncos are fickle too, but the only thing I did was change the radiator. Nothing else was touched or replaced. Thinking about playing around with various levels of blockage now too.

Good luck.

Paul

 

The OE temp gauge was variable as new. With age and possible replacement of the sensor, may not be reading like you expect. Agree install an aftermarket gauge at least as a test. Your temps might be fine. A low cost parts store mechanical gauge will do it..

 

Yes the upper hose warms up when it opens. I can also see the gauge going up till it gets between the "T"&"E " and then it goes back down to the mark before the "T".
I'm not convinced that the temp at the thermostat housing is good to measure. I have seen 165 there but I believe the coolant is warmer then that.

Yes I'm positive I have the right T-Stat. It is the exact same 333-195 that Robert Shaw sold. Now they are through TMeyer for the 400cid.


Thanks for the reply.

 

I agree. I should get an aftermarket gauge like ranger140892 also advised.. I will probably get one by the end of summer.
For now I think I'm going to move on and get back to fixing other things that need my attention. I shouldn't be that worried because it's not even close to overheating
and the the truck runs great. Thanks

 

I think thermostats start to open before the rated temperature. There's a dead band i.e. starts to open at maybe 180 and fully open at 195

 

I just spent about an hour with my Temp gun pointed at the Thermostat housing. I watched it get up to 144 and then back down to 135 before going back up to 144 and repeats.

I guess I can only come to the conclusion that the Thermostat isn't operating properly,. Which sucks because I got a 180 and a 195 both from TMeyer which was at a premium price. If its not the T-Stat then I'm stumped.

 

Heater core water valve open? Card board might do it. I don't think it would be thermostat itself.

 

I did do yet another thermostat today from NAPA! The THM-297 which is 192 degrees. I'm getting better temps with this one.
The needle is now covering the "E" in TEMP .. Considering it was on the second mark just before the "T" I feel better.
I have a hard time believing the other T-Stats where bad but oh well..

I'd like to check that Heater Core water valve incase it might be in the wrong position. Never heard of it.