Overheated - but didn't?
 

This morning it was about -20f. I started my truck as normal, let it idle for a minute and then started down the road - nice and easy.

About 5 miles into the trip I got on the highway. At this point the tranny was warm enough that the TC had locked up.

About 2 miles down the highway, I realized my temp guage had topped out at H and the idiot light came on followed by the CEL. I immediatly pulled off the road and shut the engine off. I popped the hood and everything looked okay. I got back in the truck and turned the key to find the temp guage had dropped back to where it should be. So, I started it back up and continued on my way.

When I got to my destination I pulled the code and got two codes of P1299 - which is a safe guard to prevent the engine for becoming damaged - I think.

Anyway, all seems fine and I don't think my engine ever overheated, but instead I experienced some sort of electrical malfunction.

Any ideas?

BTW, '97 F150 4.6L (w)

You got oil in that thing right?

Yup, plenty of oil.

I am convinced that this is an electrical problem (maybe from the cold ambiant temps) because the guage went from maxed out at H to the normal operating temp in less than 2 minutes without the engine running. Even with the ambient temp of -20f, I doubt any engine could cool that quickly without coolant flowing through it.

Your coolant may have froze near or around the thermostat. The coolant that was locked in place by the ice got very hot around the temp sensor. The motor shut off, created more pressure, relieved the blockage. Coolant began to flow and the temp sensor became covered with extremely cold coolant, hince the temp fall so quickly............My $1.02.


Adam

experance same problem
 

I have a 99' F150 4.6L with the same problem plus a few more. Everything you explained happened to me. Also when the truck is warming up, it builds up to much pressure in the cooling system causing coolant to blow out through the over flow tank. This problem started long before our common problem. I had some people say that it is a head gasket or a warped head. Let me know what you find out. GOOD LUCK.

So far, this is an isolated incident. I did check the coolant, and it tested good to about 25 below, so this may have been the problem. I haven't ruled out the thermostat either, but I will get the coolant changed before next winter. I don't think we should see much more than -10 below for the rest of this season.

The part that bothers me is that I just had the coolant system flushed and put all new Peak Global (50/50 mix) last winter (nov 2003). It should have held up much better than this. The original coolant held up much better.