New thermostat works!

[HiTechRedneck]

Drove from Arkansas to Bossier City La. yesterday (308 miles) where the temp was 107!!! Changed to the new stat last Friday and added fresh coolant as well as removing the engine cover. Temp never got over 200, stayed at 190 most of the time. If it can do that in temps of 107 I think the problem is solved.

 

[TrentM]

Nice! Taking my Gator in this morning to get the new one put in. After changing it in my Raptor a week ago my Trans, engine oil, & cylinder head temps have not gone over 190 verses the 220 to 260 they were always at, and we are right at 100 for heat here. Very happy with that change.

 

[HiTechRedneck]

Did mine myself but I'm 74 and been building and working on vehicles since I was a kid. Not really a hard job but Good Lord - the price of coolant now!!!!!!!

 

[TrentM]

Great that you can do that! I am semi-handy but don't trust my abilities on some projects. I have learned from experience that if there is a way to screw up the most simple job around I am capable of doing it. Don't wanna take that chance with my Gator.

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[HiTechRedneck]

LOL! My oldest son can screw up an anvil with a rubber mallet!!

 

[Action]

Drove from Arkansas to Bossier City La. yesterday (308 miles) where the temp was 107!!! Changed to the new stat last Friday and added fresh coolant as well as removing the engine cover. Temp never got over 200, stayed at 190 most of the time. If it can do that in temps of 107 I think the problem is solved.

Coolant temperatures

190f is too cold.
200f would be on the cool side as well.
205 to 210f would be desired

This is especially true of direct injection engines. Running too cold builds deposits in a greater amount.

If the engine is boosted, then there is more oil in the air/fuel mixture which creates more deposits. If you are going to run that low of a thermostat, use a catch can. Using a high quality synethic oil helps too.

Action

 

[HiTechRedneck]

Coolant temperatures

190f is too cold.
200f would be on the cool side as well.
205 to 210f would be desired

This is especially true of direct injection engines. Running too cold builds deposits in a greater amount.

If the engine is boosted, then there is more oil in the air/fuel mixture which creates more deposits. If you are going to run that low of a thermostat, use a catch can. Using a high quality synethic oil helps too.

Action

Been building engines since I was a kid (now 74) and I don't disagree that 190 is on the chili side, but it's the thermostat that we are running recommended here. Most of the time it's just over 200 degrees. I already installed a J&L oil separator and Amsoil oil and filter. Grew up with my Dad owning a machine shop so I have plenty of experience, even built and raced a pro stock Camaro when I got back from Nam. I'm old school but I stay on top of things.

 

[Action]

Me too and I worked for the company that builds the vehicle you are driving and so many other things. And none of that matters. Neither of us have designed the power train nor the engine management system in that vehicle. Not sure which 'stat was recommended and engine coolant temps below 200f* on a warmed up engine is not how the engine was designed to operate.
*which was stated in the first post for a 308 mile drive.

But it is your ride, so you should enjoy what you own.

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[TXNav]

Me too and I worked for the company that builds the vehicle you are driving and so many other things. And none of that matters. Neither of us have designed the power train nor the engine management system in that vehicle. Not sure which 'stat was recommended and engine coolant temps below 200f* on a warmed up engine is not how the engine was designed to operate.
*which was stated in the first post for a 308 mile drive.

But it is your ride, so you should enjoy what you own.

Action

If this were the case, that 190 is too "cold" why did Ford update the part? Lesser of two evils with not killing the transmission? Seems like the ultimate solution would be to leave the tstat alone but get the coolant out the transmission cooling process and have a dedicated transmission cooler like the superdutys do.

 

[HiTechRedneck]

I think that's the real question - since it was Ford that updated the thermostat and 190 - 205 degrees is running out of spec, why would they do that? Also, why would several members here refer to both motor and transmission failures due to heat?

 

[Action]

If this were the case, that 190 is too "cold" why did Ford update the part?

What is the application?
The OP has an Aviator. This forum is about Navigators
The updated part, is a thermostat? Updated from what to what?
Was there a TSB that Ford issued?
What is the update?


I went to Tasca (Ford) Parts.
Punched in a 2008 Aviator Reserve - seeking a thermostat.

2011-2023 Ford Engine Coolant Thermostat BR3Z-8575-G | TascaParts.com

2011-2023 Ford part # BR3Z-8575-G - Engine Coolant Thermostat

www.tascaparts.com

This Ford thermostat is a 189 degree stat. You have to look real close to the edge to see the temp rating.

Meaning this stat opens at roughly 190 degrees f. Restricting coolant flow to get the temp up to that temperature point. Typically the normal coolant operating temp at the thermostat is 15 to 25 degrees hotter than the temp on the thermostat on a warmed up engine. This has to do with more complete air/fuel mixture combustion. Keeping the blow-by in a forced induction engine to being burned and not stick to the intake. Better fuel economy, more power per combustion cycle and a cleaner engine are the goals.

I don't care someone wants to use. People modify their vehicles all the time without any consideration of what was designed into the power train. Operating startegies that were the norm in the 1980s are no longer used any more.

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[TXNav]

Since this is a Navigator forum, I'm moreso pointing to the Navigator thread where this has been discussed extensively on the 4th gen navigators. RT 1252 is the newer part that replaced RT (1238?). I'm hard pressed to believe a transmission should be running at 210*+. If nothing else, the repeated failures certainly can't be a coincidence.

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[HiTechRedneck]

OK - sorry about the uproar! I USED to have a 20 Aviator but it was totaled July 15th. I now have a 20 Navigator Black Label. I had neglected to update my profile page until now.

 

[Action]

TX Nav
You are speaking about a transmission thermostat?

I am on board with transmission fluid temps under 200 degrees f.
In fact under 180 if possible.
It has been some time since I got transmission fluid data. I am not towing heavy trailers as I once did. Unlike coolant, heat kills transmission fluid. Or at least it did in stuff I read about 10 years ago.

You can cook coolant to 300 degrees and it is still coolant that works.
Do that with transmission fluid and it is done.
Attached is an old chart on transmission fluid and temps.
The other thing about transmission fluid is the temperature is cumulative. (unlike coolant)
Heat it up a number of times and then run at lower temps and the ttransmission fluid is still cooked over a shorter period of time.

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[Action]

New ride new part. 2020 Navi BL

2017-2022 Ford Engine Coolant Thermostat HL3Z-8575-B | TascaParts.com

2017-2022 Ford part # HL3Z-8575-B - Engine Coolant Thermostat

www.tascaparts.com

This T-stat HL3Z 8575 B comes in at 182 degrees f. Which means it starts opening at 182 and is likely fully open at 197 to 202. Again with engine coolant temps in the range just over 200 degrees on a warmed up engine. (at the thermostat of course)

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[NavigatorPro]

I think the issue effects the Aviator too. My 2018 Navigator 10 speed failed at 70000 miles. It also had other serious engine problems. Heat may or may not have been the issue but I dont think it helped. Both Ford and GM 10 speeds used to run way over 200 degrees. I remember mine running to 220. I guess COVID gave the engineers some time to think because both GM and Ford decided to run the transmissions cooler.

The old conventional wisdom is heat kills the transmission and I do not doubt that.

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[Action]

This thread started out about coolant and now the discussion is about transmissions.

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[NavigatorPro]

Well...when you say coolant temperature I think transmission.

 

[Action]

I will have to remember that!

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[Black Label]