What is considered "overheating"
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
2001 service manual cd for the Superduty:
Thermostat Opening Temperature
Initial 5.4L 86.7-90.6øC (188-195øF)
Fully open 5.4L 97.8-101.7øC (208-215øF)
Initial 6.8L 83-87øC (181-188.6øF)
Fully open 6.8L 96.7-100øC (206-213øF)
Which is why I said 220 is about the highest I'd run without pulling over and cooling off.
Thermostat Opening Temperature
Initial 5.4L 86.7-90.6øC (188-195øF)
Fully open 5.4L 97.8-101.7øC (208-215øF)
Initial 6.8L 83-87øC (181-188.6øF)
Fully open 6.8L 96.7-100øC (206-213øF)
Which is why I said 220 is about the highest I'd run without pulling over and cooling off.
Senior User
Joined: Mar 2007
Posts: 348
Likes: 0
Originally Posted by krewat
2001 service manual cd for the Superduty:
Thermostat Opening Temperature
Initial 5.4L 86.7-90.6øC (188-195øF)
Fully open 5.4L 97.8-101.7øC (208-215øF)
Initial 6.8L 83-87øC (181-188.6øF)
Fully open 6.8L 96.7-100øC (206-213øF)
Which is why I said 220 is about the highest I'd run without pulling over and cooling off.
Thermostat Opening Temperature
Initial 5.4L 86.7-90.6øC (188-195øF)
Fully open 5.4L 97.8-101.7øC (208-215øF)
Initial 6.8L 83-87øC (181-188.6øF)
Fully open 6.8L 96.7-100øC (206-213øF)
Which is why I said 220 is about the highest I'd run without pulling over and cooling off.
BTW, thanks for the concreate info. I much prefer it to answers like "well, my dad always said do thus-and-so", or "she feels like there's a lot more power when I do thus-and-so".
Last edited by emptyd; Aug 18, 2007 at 11:13 AM.
Senior User
Joined: Mar 2007
Posts: 348
Likes: 0
Thanks again for the info! I guess I had been too conservative on temps.
So do engine temps work like tranny temps? That is to say, when people are talking tranny fluid temps they say things like 240* is ok, but 220* is better because your fluid will last longer.
Does the same hold true with coolant temp - 213* is ok, but 195* is better because your engine will last longer?
I guess another way to put it might be if two identical engines ran their entire life at 195*, and 213*, would the 213* engine wear out sooner?
So do engine temps work like tranny temps? That is to say, when people are talking tranny fluid temps they say things like 240* is ok, but 220* is better because your fluid will last longer.
Does the same hold true with coolant temp - 213* is ok, but 195* is better because your engine will last longer?
I guess another way to put it might be if two identical engines ran their entire life at 195*, and 213*, would the 213* engine wear out sooner?
Thread
Thread Starter
Forum
Replies
Last Post
77 Dent
1973 - 1979 F-100 & Larger F-Series Trucks
110
Sep 18, 2025 08:50 PM
