Not likely, theyre seperate sensors, on seperate circuits, at least on a 7.3.

 

If the idiot light comes on it is in fact overheating, i cant find the spec right now but i think the idiot light triggers at 265 degrees. Back when i didnt know much about diesels i fried countless head gaskets and 2 engines in my 85 4x4 f350 cab and chassis because i liked to get it stuck in mud and redline it out, moral of this story is get a mechanical gauge and find out why it is overheating. Also my 91 had the same problem you described and it turned out to be the radiator clogged.

 

"Houston, we found the problem"

 

That would be a problem for sure, i have never seen one broken like that before and i have worked on a lot of idi engines. Glad you got it squared away

 

Definitely broken.
Wow that is a lot of goopy RTV some one used. I think there is a black rubber seal that
goes around the edge of the t-stat. Maybe it was missing why the use of RTV.

Charlie

 

Wow!

Let us know how it runs when you get it back together.

 

What's more concerning is not the overheating, but what the hell would have caused the t-stat to fail like that. the pressure tore the metal. That's a lot of force. I seriously doubt the waterpump could cause that kind of pressure. Could a leaky HG could leak combustion gases into the coolant..... Maybe when the engine was cool (before the t-stat opens), a leaky HG could overpressurize the coolant system, pushing the t-stat to collapse like that. But I would expect the pressure to find the path of least resistance and go back up the opposite of the coolant flow to the lower rad hose and radiator, being relieved by the rad cap.

Maybe the t-stat died from metal fatigue. IDK. That's just a really odd failure for a t-stat.

 

Overheating it is what caused the failure in my opinion.

My guess is the thermostat wasn't opening enough or at all and the engine cavity got over pressurized when the temps hit 260ish.

The reason you need an oem style thermostat is because underneath it you'll see a port, with the thermostat closed this allows the coolant to circulate inside the motor so it warms up quicker. When the thermostat opens it seals this port and the water pump can apply full suction to the rad.

With the wrong (gassed) style thermostat even with it open the pump won't be able to have enough suction on the lower hose and it'll run warm or even overheat depending on load and outside temps.

Motorcraft or international brand is recommended because they're supposed to fail in the open state, the aftermarkets fail in the usual closed state.

 

it looks like corrosion where that one ear cut loose too, But my old Eyes can't tell too much from Pictures nowadays and now Reno is fighting the Oil in water issue

 

Hold it now, hold it... That's the 7.3 with the goopy oil in coolant issue. The 6.9 had the broken thermostat. I love these IDIs and would buy another if the right deal came up.

Back to the 6.9 and broken t-stat. The one in there was a Ford/International type, deep canister. But as for that port down there below the thermostat, I checked that out with my finger and it goes nowhere. At least on my truck. I suspect that it's in there for clearance when the thermostat rod is fully open. The coolant jacket goes off to the side down the passenger cylinder bank.

The t-stat seems to have broken in the downward direction, looking at the break lines. That would not suggest that overpressure in the cooling jacket caused the break. I remember talking with the guy from www.AccurateDiesel.com about the level of vibration that these atmo IDIs generate. BTW, save that bookmark. He makes brand new IDI injector lines for $300 and change, which is a killer deal. The wrench who installed mine left off and lost the braces that group them (my master tech friend fired him for that and other sloppiness). I asked the Accurate Diesel guy if they were really necessary and he went off a bit about the vibration forces that can even tear apart your injector lines if they are not grouped, and in just the correct places.

So, long story short, I bet 420ci-long-stroke-high-compression vibration killed my thermostat. And then the body of the t-stat slipped in there cockeyed, blocking full flow. Look at my OP, after shutdown and external radiator cooling, @calvinhg motored serenely home with the coolant temperature falling ... because the thermostat core happened to fall in a position that did not block flow.

Now, putting on my asbestos suit as we used to say, I did not use a Ford/International new thermostat. I heard y'all clearly, but could only find that model in 195F. I'm old, and Texas is hot. What old has to do with it is I remember running my cars on 160F thermostats, always, in the 70s when I was building hot V8s. Cooler is better for power. More power on a cool day. The hotter thermostats came in with the dreaded emissions controls of 1973+. And Texas is hot. Tonight the weatherman says 81F at midnight, with thundershowers. So I chose a standard Stant-style thermostat by MotoRad part number CTH 13358, 180F.

Ducking and running now .... hoping this pretty pic stalls the mob long enough for me to make it past the castle moat...

www.accuratediesel.com

 

LMAO ... and yeah I hear you it is hard to find the 180 international Tstat now as Power Equipment has changed hands and I suspect they no longer make them ..... it's been at least 10 years since I had to buy one, and I'm not real sure Motorcraft ever made one.... so I'm with you on the Motorrad unit, they are a Quality Tstat Robertshaw Series, so I doubt you will have any issues with it.

MY BAD for the CornFusion on the 6.9 7.3

and yeah, I hope that front cools us off a bit as I have work to do on top of my slide in camper and it's just beastly hot with high humidity down here... I can't even make it to the mail box and back to the front door without loosing a Quart of water

 

FWIW, both my 7.3s that ive done t-stats on had a cracked post, but neither failed like that. One was stant, one was motorcraft.

 

Reno, did you install the Stat-style thermostat yet? Did it fit well?

BTW, that's a good deal on the injector lines. Luckily, I have a spare set from the 7.3l IDIT sitting on an engine stand in my shop. I already had to salvage one of the fastener brackets from that set when I lost the original in my backyard somewhere.

 

Yep, it fit fine. I did get the correct gasket at the Ford dealer. It's not cheap, but it fits right up to the thermostat, as it should. Truck runs great now. See my slow cranking thread out here...finally fixed! Now I need to address oil consumption. She originally came with only a 4spd and 4.10 gears, so I suspect oil control rings are worn.

 

Good to hear that the thermostat worked well.

How fast does your truck use oil? Does it burn it or leak it. I change the oil every 5k miles, but the rate at which my truck uses oil I end up using 10 quarts every 2.5k miles. I think most of the oil I loose drips on the ground. I've read about other trucks using oil alot faster, but I know my truck doesn't leak slow either.