I just replaced the 305 in my 85 trans am with a 350. Break-in was going well, had 800 miles on it. I was driving on the freeway a few days back, went about 15 miles, exited and stopped at a building, went in and did my business. I drove out back onto the road, and to my horror saw that the temp gage was showing 240 degrees. And it was slowly climbing toward the red. The fan was not working. I immediately stopped the car, waited awhile for it to cool below 240, then started it to get as far as I could. Drove about three miles, it stayed at 240 or above. Finally I had it towed back to the shop, the fan was fixed, BUT driving the next day, outside air temp 100 degrees, it stayed at 240 all the time, about a 45 mile drive. As a precaution, I replaced the radiator cap. Now the engine temp stays at 220 pretty consistently.

Here is my concern. It is a newly rebuilt 350, with 800 miles on break-in. Has Hastings cast rings. I am HOPING the engine has not been damaged, being so new, and driving hot like that for perhaps 100 miles all told. I did not notice any boil-over, heard no sounds of metal expanding. I also understand that the temp gauge does not necessarily register the true temp.

Can anyone shed some light on the risks of damage to the engine?

Dave

 

probably no damage, it would be pretty obvious if you blew a head gasket or something.

make sure the air damn is there and in good shape, and if the fans are now fixed you should be good.

And yes, the factory, and even aftermarket gauges are not totally accurate. For that matter, both my cars, with the origional gauges, will run at about 230, by the gauge. I know thats not the correct temp, and have verified it by thermometer.

Also, the factory fan settings are upwards of 240 degrees anyway. The cars are designed to run hot for emissions reasons IIRC.

 

Thanks! Air dam is okay, and fans are now working. It is good to know that the temp gauge shows hotter than actual. Never was any boil-over or steam escaping. I just wanna keep this new motor nice. Now she runs just under 220 by the gauge, which I am guessing is closer to 200 deg. actual. The car is a daily driver, so I'm looking for longevity, BUT enough power to deal with the rice cookers. The 350 plus CAI makes a noticeable difference, I spun the wheels without even trying the other day.