03 Navigator Cold Weather Operation

The coolant overflow wasn't low after this procedure so didn't add any antifreeze. HOAT??? Never heard of that before I guess I have to read up more, whatever happened to the days where there was just one coolant? lol
The temps dropped here to the negatives so won't be doing anything soon but will probably have a shop do a test and flush. Is the Ford recommended coolant good? I know many don't like the Ford Gold that is recommended for my 03 Excursion which has Amsoil ELC instead.

BenK wrote:
Be sure to flush the coolant system, as a 2003 will have HOATs (Hybrid Organic
Acid Technology) coolant...which does NOT like O2/Air in the system

What did you top up the coolant system with?

Since it is 11 years old and ask if you know the previous owner(s) ever flushed?

Suggest to be safe and flush with whatever your manual says (HOATs) since you have
opened up the system to expose O2/Air into it.

Always glad to hear someone's DIY success stories !!!

Be sure to flush the coolant system, as a 2003 will have HOATs (Hybrid Organic
Acid Technology) coolant...which does NOT like O2/Air in the system

What did you top up the coolant system with?

Since it is 11 years old and ask if you know the previous owner(s) ever flushed?

Suggest to be safe and flush with whatever your manual says (HOATs) since you have
opened up the system to expose O2/Air into it.

Always glad to hear someone's DIY success stories !!!

UPDATE: Normally I start it up and get on highway to work so heat comes up almost normal but today just driving it around running the house running errands it stayed on the bottom peg so I stopped at NAPA and got a new thermostat and gasket. I don't do any work on my vehicles but my daughter was sleeping so that ruled out a shop so I did a search on internet and only found on thread on changing thermostats on the 32 valve 5.4L. I swapped the old one out with the new in about 20 minutes in my driveway (daughter sleeping inside) with the wind blowing and temp a steady 7F (with bare hands). It was a little tight for my big hands but I took my time didn't want to strip threads or lose bolts. Afterwards the temp gauge was at the bottom when started but I revved the engine at 2K until the coolant gauge rose up to dead middle which is slightly higher than it would ever get before. Back at idle it stayed there and only when I put the front and rear on high did it come down slightly but that was at idle. I put the front on med low and the rear on low and it got so hot I couldn't hold my hand at the front vent so I know there is a BIG difference. Tonight when I drive to work I hope to do a comparison to my normal routine. I want to thank each and everyone again. Throughout my 7 years owning TV's (had many different ones) you have all helped me with my problems and now that I am doing some work myself I hope to choke out my local stealership from lack of my funds LOL

Thanks everyone for their ideas. It seems unanimous to swap out thermostat for premium (or OEM) and change coolant. I kinda thought that but wanted to make sure by asking the resident experts.

BurbMan my plans are to to fix this up and sell it to friend or coworker. Every now and then something comes my way needing some work and I try to bring new life into it and pass it on.

BenK I didn't think of the removed thermostat because in the past when I had some that were stuck open (Mustang and Accord) the temp gauge wouldn't move at all and the heat was almost non existent but will update when the work is done. The previous owner "donated" vehicle to charity. Looking at some paperwork it still had factory warranty up to 2012. The worst part of these are the air suspension and it is in operating condition so it is just slightly neglected LOL

and if you find that the previous removed the thermostat all together...masking
a thermal issue they solved via removal of the thermostat

Suggest flushing *ALL FLUIDS*. ATF, power steering, diff, etc...as it sounds like
a well neglected vehicle

T-stat! It is either weak or stuck open.

Ditto on the T-stat and new coolant. Not sure what your plans are for the vehicle but this is a good time to look at the hoses and replace any that look cracked or deteriorating.

Be sure to look in the owner's manual and get the correct spec for the coolant. GM uses DexCool, Chrysler uses HOAT, not sure about Ford.

I'm almost certain you have a stuck thermostat. When you swap it, be sure to get the ultra, super, or premium version of whatever t-stat you get. The standard flavor often does't last long, and many of those are bad even out of the box. The difference is less than $10 usually.

BTW - the coolant in your Navi I believe is spec'd for flushing every 150,000 or 10 years, so it's probably a good idea to go ahead and get some new stuff in there when you do the T-stat.

I would start with the thermostat, granted aluminum engines do not hold heat as well, they do not operate like you are describing. The coolant should be flushed; I flush out our vehicles every 100,000 miles, I am not a believer in this so called "lifetime antifreeze." We had a Mazda 626 that we gave to our oldest grandson, it is closing in on 300,000 miles and I will be changing the antifreeze in it, giving it a tuneup, and having the timing belt changed. Regular maintenance is important to keeping a vehicle running properly.