Ok, so i have been doing some thinking and have a few questions about the thermostats we buy for our 4.9L from the local parts store.

Alot of them claim to allow up to 50% more coolant flow. That is great and all but I do have a small thing i am a bit preturbed about. If we allow more coolant through than obviously it will cool the motor off easier, but in conjunction the motor might not be at OEM operating temperature.

Coincedently if you think of it on terms as a diesel your motor doesnt burn the fuel as it should and must pump more to keep the same power. Now dont get me wrong, I am just a normal guy trying to figure out why i am running richer than usual, and it all started about the time i replaced my thermo a year ago and it is just really starting to bug me now.

So in otherwords am i wrong to assume that because the "newer" OEM replacements allow more coolant flow to keep the motor cooler wouldnt that effect our gas mileage. I lost about 1mpg if not more overall when i did this. I did the fan clutch, waterpump and thermo all at once. Fan moves smooth so i know i didnt over tighten and motor stays cool ALL THE TIME!!! I am thinking of using a thermostat that is not OEM like one i put inside the hose at the point which collant comes out of the motor to the radiator.

But i normally run at the n in town and maybe the o if i stop and go alot but even on the highway WOT with the speedo tach against for a good 20sec or so I am still not passing o in the word normal. It will touch right past it and go right back down once i let off the throttle for 30 sec or so and just keep at 80mph which is my cruising speed.

Any suggestions or input is welcome. Maybe i am thinking to hard into this but could that be the cause.

I got the idea while reading up on diesels and how they need heat to run correctly.

Thx, Cameron

 

The 50% more flow is only when the tstat needs it, not all the time.
They work by modulating the flow to keep the temp at their designed temp.
It simply means that it will open more to allow increased flow under excessive conditions like towing up a hill in hot weather.

Moving it from the tstat housing a few inches into the top hose won't accomplish anything.

 

The engine SHOULD run at a different temp with your new stat. Why would you replace the original one if it kept the engine at the right temp?

Stock spec is 195 Fahrenheit. You might want to upgrade to a 205 if you want a little more power/MPG and you don't mind the possible wear.

 

You might want to consider getting a mechanical gauge. On my truck I used to have the same problem when I was using the OEM electrical sending unit. My head gauge would never hardly get past the N always showed it ran cool. I got a mechanical gauge and it runs 190 basically all the time. The electrical gauges and sending units sometimes lie!

 

Any suggestions on brand for mechanical gauge? or can i get a basic one from a local shop?

Also how much more wear would a 205 cause? haha

 

Sun pro is a good one. You can get one at any local parts store. Easy to install. It goes in where your electronic sending unit goes. I would try a mechanical guage before you swap in a hotter thermostat. It maybe running right where it is supposed to and the electronic guage is lieing to you!

 

I installed AutoMeter electric gauges in my 1981 V8 400 except the vacuum gauge, which is mechanical:







Sure, they're more expensive, but they're made in the USA (Sycamore, IL) and they work well.

In my experience, the Chinese-made mechanical temp gauges last about one year.

The factory gauges give only a general indication of something and aren't real specific.... what temperature is R in NORMAL?

 

Not to , but ctu, thas a GORGEOUS 81!

 

I dont mind i was going to say the same thing haha.

I am not sure. All i know is that before i did replace it the temp gauge would sit a little above middle or right at middle and than my water pump went and well we all know what happens next. Good ol tow :/ lol

 

Thanks, guys, glad you like it! Although the rest of the body is a rusty POS, at least for the time being.

Lots of pictures and an explanation of how I did that stuff beginning HERE, there's more on the following page, too.

About Rock's thermostat, I would get what Ford recommends and screw the aftermarket and their claims, the FoMoCo engineers who designed the engine are best gonna know what kind of flow it needs....

 

I'm sorry, but I just have to chime in here about the SunPro gauges. IMO they are cheap C. crap, with a capitol C! I've tried many, and they always seemed to last one or two years, and then bam. Done. I would much rather spend $60 (as opposed to $20) and buy a Stewart Warner or Auto Meter gauge,and know that it is going to last. And I'm supporting my neighbor, not some guy in China. Oh, ****, is that political? Some statement that means something to Americans?