Low Coolant Temp while Cruising?

[timandsam]

Ok, this may tie into my getting hot at idle post.

On both my PiMP and autometer gauge, i am reading between 160 and 180* while driving down the highway.

I have the merkur depot shorty rad. No coolant leaks that i know of. Cooling system was burped previously. I have one temperature coming from the lower intake @ the ECT sensor, and the other coming from a sensor adapter i grafted into the lower rad hose.

This is the first time i have had working temperature gauges So i am not sure if it always did this or just started.

Does anyone else have these temps while running? Seems like it should run a lot closer to 195* while cruising.

Bad thermostat?

Thanks,
Tim

[merk23literturbo]

That's the same that I see on my cars with the same rad setup.

[timandsam]

Oh ok, thanks. Are you running a 180* thermostat?

[DPDISXR4Ti]

It's very common for the thermostats to leak. This is one place where the Motorcraft part really does seem to do a better job than the after-market thermostats. The real test will come when it's colder - you really don't want it dropping much below 160 - even that is too cold for optimal running conditions.

[timandsam]

Well from watching the gauges and feeling the upper radiator hose, i don't think it leaks. I think it's a 180° thermostat in there.


Agreed, the motor is designed to run at a certain temp. With a 180° tstat and temps in the 50-60s driving at 70mph, it just wont reach 195 it seems.

[thesameguy]

This is one place where the Motorcraft part really does seem to do a better job than the after-market thermostats.

So very, very true. I had nothing but unreliable results from two other brands, but switched back to a Motorcraft and my temperatures have been rock solid. I've got the same radiator and measuring with a VDO gauge at the thermostat outlet I see a very solid 180-190 while moving. I'm really stoked about it, because in the ten years I've had this car the coolant temps have never been this stable.

[Mike McCreight]

Cool is fine, cold is not.
If you have any way of looking at the a/f ratio, you'll find in cooler weather, the mix will go rich, as if the engine has just started.it. Bad for the engine longevity oil life, your $$ and that environment thing everyone is whining about.
Thermostat seal is important, but even a sealed closed one won't keep temps up when it's cold.
I watch my gauge, and block the rad.

[anglin]

It's very common for the thermostats to leak. This is one place where the Motorcraft part really does seem to do a better job than the after-market thermostats.

The description of the problem says the thermostat is unable to regulate the temperature. This must be happening because it's not working properly. Replace it with a Motorcraft unit like Brad said and I bet you'll see an immediate change.

[timandsam]

Ok, so i pulled the tstat. It is definitely a 192* motorcraft unit. Like i said it definately felt like it opened at 180* so for sure it is shot then i guess.

On my way home today (before i checked the forum) i stopped by Advance Auto and picked up a Stant Superstat 195*. I put it in water to test it. Opened at 195, half of it closed at 191, the other side didn't fully close until 180. Cheap junk!

So i will be taking it back to the store and replacing it with a motorcraft piece as suggested.

Anyone who bought one... do you remember if they stock these or if it took a while for the dealer to get one in? I would like to have the car back together by this weekend. I am going to call the dealer tomorrow, just curious in the meanwhile.

Thanks for the help.

[Matt01]

I dont have the shorty rad installed yet, but I have a new motorcraft t stat and my car also has the up and down temperature

[Ed Lijewski]

"I have one temperature coming from the lower intake @ the ECT sensor, and the other coming from a sensor adapter i grafted into the lower rad hose."

The lower radiator hose reading seems logical-the coolant temp there should be some degrees below T-Stat closed temp from highway speed heat-to-air transfer.

The low reading(s) from/at the ECT don't serm logical at all (even assuming the leaking T-Stat hypothesis).

YMMV

[timandsam]

Ed, agreed. It would make sense to me though if the thermostat was malfunctioning and not closing. Then the entire system would have nearly the same temp.

Picked up a motorcraft 192° stat today. Going to put that in and see what it does.