1/8" hole in new stat does real well. Still looks like the stat "snaps" every once in a great while(twice during 60 mile hiway commute). Mileage at 24.5 now with this set up.

 

What with some recent work I did on my '93 Taurus wagon (3.8l) I had to dig this old thread up to comment.

Rschap1 did a whole bunch of work (and great reporting) to try to stop his temp gauge from flucuating. the t-stat seemed to be a big part of things, but I have another item to think about.

My 3.8 also sends the gauge back and forth at time. A coolant flush and a new radiator helped smooth mine out a bit (had to manually "burp" the system as the Haynes manual suggests), but it still does its dance...except when the AC is on.

Now, I'm assuming that the 3.8 and the 3.0 use similar fans and fan modules. I could be wrong.

What I've found out about the 3.8's fan is that it has a large CFM rating, such that it is in demand by mustang and other sporty car owners because of its cooling capability...$25 from a junkyard is lots cheaper than aftermarket. The issue is that the fan is two speed and the control module isn't set up for the best cooling, i.e. that high speed doesn't come one soon enough.

In short, it stays on low speed until the motor gets really hot or until the AC is turned on. And with the AC cooler in front of the radiator (and on my car soon the trans cooler) that ain't enough.

So I've experimented now that the weather is warmed up, and I commute over a 15 mile mountian pass with over 6% grades in places. Get this: The engine runs cooler and with almost no gauge movement with the AC ON!. IS that backwards to common wisdom or what?

In fact, if the AC is off and the gauge starts moving up as I climb the grade at 55 mph, (outside ambeint temp around 80 degrees F) I'll turn on the AC, adjust the cabin temp to suit, and watch the gauge go down.

This tells me I need either an aftermarket control module (programmable), or just wire in a toggle that turns the fan onto high when I need it.

Hope this helps somebody.

 

You have really dug into the fan issue. I still do not know if I can say 100% what the root cause of my gage's dancing up and down so much was. The stat really effected the high end of the dance's range, and limited the amount of it somewhat, but was not a total cure. I was unaware of the "burping" procedure and that could come into effect. I was under the impression that the design of the reservior (de-gas) bottle eliminated a need for burping. Lately, whether caused by finally gettting the gas out, thermostat cycling enough to "wear in", or change to a little warmer temps, the dance is almost completly gone. WISH I knew what it was. Thanks for adding your info to the post. Maybe it will help some others too.

 

Temp gage now steady as can be. Not sure if this is from weather now in the 70's not 20-30's or if I had and air bubble finally break free..?

 

Interesting. Still sounds like mostly a sticky thermostat during cold weather.

I was also wondering since the motor had sat for a long time if there wasn't pockets of minor corrosion/crud in places in the cooling system, caused possibly by air pockets just sitting there. Then, when the engine heats up, those spots got hotter and boiled the coolant, which sooner or later got flushed through the system and spiked the gauge.

Somewhere on FTE I saw a post where Redline "Water Wetter" was suggested to help prevent hot spots in the engine. Here's two links about WW:

http://theoildrop.server101.com/cgi/...c;f=5;t=000558
http://www.redlineoil.com/products_coolant.asp

In answer to the "burping" of the radiator, it had to do with squeezing the upper rad hose when the engine was warmed up with the t-stat open. Haynes said to remove the radiator cap, but I found that just caused coolant to jump out of the radiator. When I squeezed the upper hose I (cap closed) I distinctly heard a burping sound in the overflow tank as air flooded into it.

When the engine cooled down the cooling system sucked the tank dry, so I had to refill it, warm the engine up again, burp it, and turn it off to cool, it sucked a little more down out of the tank, and hasn't used anymore since.

My cooling gauge still travels a little, but not hardly as much, and as I mentioned above, turning on the AC keeps it parked in a cool spot ('cuz the fan runs on high).