how hot is too hot?

Stupid,stupid,stupid me. I have a work-in-progress Kellison with a very tight 1969 Olds 455 and late model L700 R4 overdrive trans. I put in a new Griffin radiator and Be Cool 3,000 CFM fan under an aluminum shroud. I don't have a thermostat installed yet and turn the fan on manually.

I put the car in a show this weekend and while driving home yesterday, I was daydreaming on the show experience and forgot to flip the fan switch. 15-20 minutes later after stop-and-go traffic I woke up and looked at the temperature gauge – 268 degrees!!! I flipped the switch and within a minute it was down to 230 and then after 4 minutes stayed down to 186-190 for the rest of the 1-hour drive home.

I didn't smell radiator fluid nor did it appear to spew and when I got home it only took 1/2 gallon distilled water/antifreeze mix to top off. The hot trans fluid was off the stick but after it cooled, it registers full. It was 1/2 quart down on my Amsoil 10-30.

The question is now what? it seems like a I dodged a bullet but did I really? Could the oils and fluids have broken down so they've lost their effectiveness? Should I do a complete fluid change to be safe? Any other advice besides "put in a thermostat you idiot"?

Thanks.

 

Your good to go. 268 aint bad, just be careful in the future.

 

Sounds like you woke up just in time! As long as it is running ok and not leaking due to gasket failure or cracks you may be ok? Just monitor closely the next few times you run it.

 

I would change the oil just to be safe.

 

Whew! Thanks. And IT WILL NEVER HAPPEN AGAIN.

 

You should be OK......just keep an eye on things for the next few weeks. Pay attention to engine noises no matter how small and leaks, also. As you were told....it wasn't hot long enough.
Might think about this.....hooking your fan up to an adjustable thermostat and have a safety light come on at a predetermined Temp........say..............240.

 

Remember todays modern fuel injected cars run between 200 and 220....

As stated above, drain the oil and monitor, you'll be fine..... You would know by now if there was a problem....

 

What he said!!!!!!!!!!!!!!!!

 

or wire it up so it's on whenever the key is on.

I sure love mechanical fans....

 

if your trany fluid goes through the rad, and looks anything less than brand new, i'd flush it. Heat is the #1killer of slushboxes. and "hot trans fluid was off the stick" till it cooled- tfluid expands as it heats, was the car running when you checked it hot, then off when it was cooled? bet you're low on fluid, too (coulda dumped some out the vent).

http://www.tciauto.com/Products/TechInfo/trans_life_expectancy.asp

http://forums.nicoclub.com/zerothread/337645