2007, 5.4...

Curious about what engine temp i should be starting to worry at. I have an Ultra Gauge and it has the alarms on it. I am about to tow my big trailer out of Texas (aka Hell) and am curious as to what engine temp I should set the alarm at?

Currently while not towing anything, and it being almost 115 degrees outside, I have seen 199 degree engine temps. What would be a temperature to start worrying at so that I could set my alarm?

 

220.

 

So set the alarm for 220, or set it for a little lower so I dont get to 220?

 

220 is getting warm, but not dangerous. Keep in mind, 200-205 is ideal for that motor; 199 is nothing that should even catch your attention. My personal limit is closer to 230. If I see that, I'm pulling over and/or changing the conditions that caused it to get there. Even 230 isn't going to boil over. I'd agree 220 is a good spot for an alarm and then watch it close from there.

 

thermostat starts to open at 190 and is fully opened at 210. cooling system is pretty stout on these trucks.

I'd be more concerned with trans temps while towing in 100+ weather

 

Under 15 psi pressure, a 50/50 mix of coolant/water boils at 265.

 

According to jbrew these motors prefer to run hot. I know mine on the highway hangs right around the 208 mark (as monitored on my Gryphon). I have electric fans so I set my low speed fan to come on at 210 and the high speed fan at 217. Before I upgraded the rad I saw the warning flash on the Gryphon at 228 a few times while towing. I don't think the truck hits limp mode until 235. I agree with Galaxy at 230 I am pulling over but I prefer to keep it under 225.

 

When you say you set your low speed fan to come on at 210, where did you measure that temp? I measured mine at the radiator where I have my temp sensors, however, my low fan comes on at 190 at a stand still. Should I use my ultra gauge for the temp? I would much rather the fans not come on until actual 205 or so for the low and 215 for the high...

 

I think the ect(engine coolant temp) fsm(fail safe mode) happens when the coolant hits 238*f....

the other numbers I have are for the CHT(cylinder head temp) in the older 4.6's.....255*f CHT for the fsm to occur and 330*f CHT when the pcm shuts down the fuel....

in the MY of 04 with the NBS change the coolant senser was deleted and the temp for the coolant was an inferred reading from the CHT derived by the pcm.....

 

He is an imposter. As I would NEVER say that.

 

I measure the temp on my Gryphon. If you have an Ultra Gauge I would definately use that. It sounds like you have the push in rad probes and if you do the fans may still not come on exactly when you want. I found the rad probes were less than accurate. My fans worked and came on when they should at a standstill but moving with the wind in the rad was another story. I now have a wet temp sensor in the upper rad hose.