First of all, I would like to say that this is my first diesel! I have a friend that is quite obsessed with the spark-plug-free engines, so I do have a little bit of experience wrenching on them. This is, however, the first one I have owned.

My issue is the engine temp gauge (aftermarket mechanical type) reads abnormally low. The highest I have seen it climb is 160*. I believe these engines are supposed to have about a 190* thermostat? My radiator looks new on the outside, but a little gunky on the inside. I'm thinking I need to flush the cooling system, and possibly replace the thermostat. I'm guessing it's either stuck open or missing. Any special instructions on flush procedures? I have flushed gas engines before. Also, coolant type? Good ol' critter-killing green stuff? I read the "new owner FAQ", but it was a little vague on coolant type (seemed like there was a debate going on).

I'm planning a couple of other major undertakings, the thread is here:

https://www.ford-trucks.com/forums/1...-t19-swap.html

 

sounds like your thermostat may be stuck open or missing. buy only motorcraft for this.
that or else your aftermarket temp gage is inaccurate - you can test it by putting its sensor in a pot of boiling water and watching how it reads.

for flushing it out, its just like any other engine, gas or diesel. the use of a strong chemical made for the purpose may find a weak spot in your heater core, radiator, or oil cooler, and cause a leak to appear a few months earlier than it otherwise would, so i would suggest only using one if you think things are pretty gunked up where thats necessary. there are a couple drain plugs in the back of the block that may be of help to you as well.
like any other, use the garden hose to push through everything in both directions until it flows clean, then drain it and use distilled water and coolant, or pre-mixed coolant.

for coolant, all diesels are best run with a coolant that include SCA's. you may choose a coolant such as fleetcharge that comes pre-charged, or a conventional green coolant labeled as being ok to use with SCAs, and add SCAs yourself. i choose fleetcharge, but for any of them, you'll want to check the SCAs every time you change your oil

 

Mine ran cold too. Both of my trucks had cheap Chinese T-Stats in them. Both T-Stats were broken exactly the same:

 

Typical Chinese-made failure.

I will be using the FleetCharge coolant from Tractor Supply. Thanks for the heads-up on the block drains; I will certainly be using them. I have well water laden with iron, so I will have no choice but to use distilled water. I have run regular tap water in past gassers, but that was also city water.

O'Reilly auto parts website recommends Motorcraft RT1049 190* thermostat, and sells it for $25. Sound about right?

 

Sounds about right, you might save a couple of dollars @ Rock Auto, but it is kind of a pricey T-Stat, makes sense though it is quite a bit more T-Stat than the small ones in a gasser.

Not to split hairs, but I believe the proper temp in 192*, but I imagine their system just doesn't show the odd number, when you get it out of the box it will probably have 192 stamped on it.

 

I would say t-stat also. I would be leery of any t-stat that didn't come from Ford or IH. It is too big a risk to worry about 5 bucks one way or the other. IIRC my last one was 26 bucks from the dealership.

Here is a thread with pics of the drain plugs.

https://www.ford-trucks.com/forums/1...ng-system.html

 

O'Reillies carries Genuine Motorcraft. I got my plugs there. So if anyone needs Motorcraft local for a heck of alot cheaper than Ford, O'Riellys is great. For what its worth, my t-stat from ford was 190. The one i could have ordered through IH was 195*