Did anyone find out the reason for the cold running T SATS in our trucks. Mine just started this issue too.It's running 182-186* with the ambient temps below 45*. It not too good for the heat in the cab or the fuel economy. Mine is about 8 months old with 15,000 miles on it. Just throwing this out there.....Bill

 

I haven't seen the cause for it either. I know alot of people have the same problem.

 

Mine runs a fat and happy 190* all summer, then hits 184-186* in the winter. Done it that way for 6 years now, that's why I run (and strongly advocate for) grille covers. Between the t-stat's tolerable error, and the % error on the sending units, I'd say 5-8* either way is really a wash and there's not a lot you can do about it.

I kind of wish there was a 203* t-stat for the 6.0L like for the 7.3, but I'm not sure if programming changes would have to be made since the fan is controlled by the computer.

 

I just ck'd the receipt,it was 7 months.I wonder if they would warranty it.It going to get real cold next week. I don't want to deal with it then and then have the same problem

 

I was just thinking is the 7.3 203* stat the same size as the 6.0 stat? If so, we could just take it out of the housing and put it in and get more temps for winter maybe some more mpg's too

 

A couple of weeks ago I did a 2.5hr drive in upper 40* ambient temps and never broke 173 ECT even on the highway at 75mph! I replaced the Stant (I know, but I've tried a MC also) thermostat and a very close inspection shows no rubbing or unusual marks on it. It appears to me the upper section opens first to allow flow to the heater core and a separate valve is for flow through the radiator.

I bought a Murray Plus+ this time, the computer at O'Riley's says it's 191* and so far it's right on the money according to my ScanGauge. Guess I'll see how well it lasts. I'll post back about it next fall .

I think this is the first time I've changed a t-stat by it's self (not doing other work) and noticed somthing kinda cool and handy to know. My truck is an '06 and the EBP sensor isn't near rhe thermostat so if you have an early truck you'll have to consider that also. It took all of 15min to change it out and 6 or 7 of that was waiting for the coolant to drain. I dropped a couple of gallons and then pulled the clamp on the upper hose on the radiator. Pulling the two bolts holding the housing in place, I had the stat/upper hose on the bench in a couple of minutes. Easy peasy! Of course getting the hose off the housing wasn't an issue on the bench but I realized I needed to index mark it before taking it apart so the hose would be oriented correctly when I put it back in the truck. Then I saw it!



There is an arrow on the hose that lines up with a mark cast into the Tstat housing. Sorry if I seem too happy about this but it really makes this a quick job. Trying to tighten the hose clamp after it's back in the truck would be possible but this makes it much easier .

Here's a pick of the (new) Murray Tstat vs the old one. I' thinking the upper part of the valve would open sooner to allow the heater to warm up quicker and the lower part would would be flow to the radiator. (Maybe I got that backwards?) The spring is bigger on the bottom section on the new one and the main part is copper instead of brass. It does look a little simpler and cheaper but we'll see.



Anyway, don't be afraid to change that weak thermostat if your temps are low, the worst part is pouring the coolant back in the degas bottle.

 

I'm not worried I just don't have the time to waste,I know the job is a piece of cake.I'll call ford and see if they will warranty it. If not,I might go down to XDP diesel and see about the 7.3 stat and try a experiment

 

I've encountered crappy t-stats for Ford FE engines and also the Ford V6 2.9/4.0. It isn't just a 6.0 problem... it's just crappy manufacturing.

On a positive note my Motorcraft t-stat is doing well after a year. It runs 190-192 driving in the zero degree heat wave lately, but sitting at a long stoplight or some other long idle situation and the temps creep down to 187-189. As soon as the truck is moving the temps come back up.

Josh

 

During the hot Texas summers mine runs close to 203 as the median, has a spread of about 198-207ish. Now that winters here, I'm barely seeing mid 180s. I've tried 2 different MC thermostats and no change. EOT is always 7-9 above.

 

Me too. 196-198 is the norm with 95+ ambient. Not unusual to see 200-203 again stopped, sitting at a long stoplight, freight train etc.

My temp spread @ 65 is a tad closer with the cooler temps as well.

Josh

 

I have a new MC stat, 186-188. Better than my 172 with the old one. Still have minimal heat at idle. 0f temps and getting into a cold truck. No puking but I did have a clogged oil cooler a while ago. I flushed everything before my 1st cooler swap. I wonder if my heater core is plugged too.

 

You aren't getting heat from the vents at 172* ECT? I'd agree to start thinking a clogged heater core. Mine starts putting out good heat around 150-170* (roughly when the idiot gauge on the dash starts moving towards full), and it blows like a furnace at 190* to the point I have to turn to **** halfway back to the blue range. This is with outside temps below 32*f.

 

Had this same problem not too long ago...

Before, running 70 mph in 40-50 degree weather, I couldn't get oil or water temps past 182-184 degrees. I pulled the thermostat, swapped in a new MC thermostat, and now without problem my truck can easily maintain 188-190 degree water temps and up to 193 degree oil temps in 30-40 degree weather.

I now get better power and smoother running engine now that it's able to heat up properly.

Mine has the 2 year unlimited mileage warranty from Ford, so if or when it fails, it won't cost me a dime.

 

100 degree ECT is enough to start thawing the windshield. 140 ect is getting pretty good at warming the cab. 190+ is roasting, I usually turn the heat blend halfway or just shut off the heat for a while.

Josh

 

Well I have not put the new T-stat in yet but I did do the cardboard and
now I am seeing 190º~194º but it still drops back to 188º if I slow down.

I don't get heat till I see the ECT at about 100º EACT won't turn it on till then.
So I don't get the COLD blow.

Sean