Hey everyone,

So I've been driving my FEH for the past week and what I've noticed most so far in daily driving is that it takes a long time to be able to go EV. I have a Scangauge and I had that set to CHT and I now believe there might be a thermostat problem after monitoring that the past few days.

The CHT will get to about 170 fairly quickly, and then anything above that takes much longer. For instance, I was able to cruise down the highway this morning on my way to work at about 60 MPH and the CHT would barely get to 180 and only go higher when I was accelerating. I finally got it above 190 to allow EV after traffic slowed and then sped up again and I gave it some more gas to try and get it up to temperature. I have a 30 mile commute and for the rest of my drive it never once got close to 200.

My question is how normal is this? If there is a problem can I replace just the thermostat or only the entire housing? How much for it and where is the best place to order the part?

Thanks a lot.


Edit: One thing I forgot to mention is that I live in Dallas and it's been close to 80* in the mornings lately.

 

The T-Stat stuck open is a common problem I've heard, but most people don't know how to detect the problem. With a proper working T-Stat, you should be at about 140F to go EV. I think the T-Stat is sold with a housing, but I don't know the cost. If it is sold with or without the housing, it may be wise to replace the housing because it may be causing the T-Stat to freeze open because of corrosion.

The reason I know the T-Stats are a problem is Ford added a special sensor in my '09 FEH to detect a stuck open T-Stat. The '09 Workshop manuals spells out added or deleted systems and the new sensor was added.

Gary

 

Okay, they didn't use/have a coolant temperature sensor but used the cylinder head temperature somehow to calculate the coolant temperature. If your T-stat was stuck your engine wouldn't warm up so why wouldn't one see that on the dash gage?

If you have something added, how were you seeing a stuck T-stat if that happened?

It's in the electrical manual but wasn't in your vehicle when built?

I have seen in the '09 FE manual an early and late model where the front side marker lights were added to the circuit monitoring system.

 

Cool thank you for the information! I went ahead and ordered one at Autozone for a little over 50 bucks and I'm going to do my best to get it put it over the weekend. I've heard that it can be somewhat of a pain to replace.

Also, the part includes the entire housing and you cannot replace the t-stat even if you tried, as I understand.

That's very interesting that Ford put an additional sensor to make sure it's working properly. You'd think they would design a better t-stat and housing before that.

Anywho, thanks for the response!

 

The engine temperature gauge was replaced by the Hybrid gauge and makes it difficult to monitor engine temperature.

 

I get to 190° in about 5 minutes and 220-230° at normal highway speeds.

 

Not to mention that there is no water temperature gauge, the traditional method to measure engine temperature for water cooled engines.

 

Bill, you're not making any sense to me in this post. Yes, the CHT sensor is used by the PCM to infer coolant temperature. If the head temperature is on the cool side, the coolant temperature is inferred cooler also by the PCM.

In the Introduction Section of the '09 PC/ED manual, it says "What's New in this Manual" which list 13 items. One item states "NEW enhanced thermostat monitor". This has nothing to do with "front side marker lights". From what I read, the PCM uses information from the MAP, TP, MAF, CHT and CKP sensors to monitor for an for a stuck open thermostat. It's a new enhanced monitor system.

Gary

 

You stated that that Ford added a sensor on your '09, as if you didn't have it at purchase.

You stated:
The reason I know the T-Stats are a problem is Ford added a special sensor in my '09 FEH to detect a stuck open T-Stat. The '09 Workshop manuals spells out added or deleted systems and the new sensor was added.

The side marker thing is something where there are two different electrical circuits depending on when the vehicle was built but maybe that's only for an FE. I mentioned this only because you stated that a sensor was added.

I have 14 items list on that page, none of which is anything about T-stat monitoring. What's the date at the bottom of every page?

You made it sound, at least to me that it was added to "your" vehicle but really it, if anything is the '09MY.

You either have a MAF or MAP not both.

 

Nothing added to only my '09 FEH, but the date of my manual is 8/2008 which is for all '09 Ford Escapes with this "New enhanced thermostat monitor". T-Stat is my short version of the thermostat.

You're wrong, there is both a MAF and a MAP Sensor. The Manifold Absolute Pressure Sensor has a Integrated Intake Air Temperature Sensor. It is part of the EGR system.

The Mass Air Flow (MAF) Sensor measures the amount of air entering the engine so the PCM can calculate the required fuel injector pulse width in order to provide the desired air/fuel ratio.

Gary