Cooling issues

[rhyne]

I have a freshly rebuilt 352, running hot at idle after only 10 minutes and overflowing. I upgraded the radiator and cooling fans..which i think is my problem...i rigged the power up to run the fans so i dont believe they are getting enough amps to run fast enough to cool suffeciently. Which got me thinking about a bigger alternator and hey why not a mark viii fan...but how much cfm do i really need? I have 2 fans rated for 1750 cfm.

[DuckRyder]

You got the original fan? Can you un-upgrade it to see if that helps?

Who rebuilt it? Head gaskets on correctly?

[rhyne]

I rebuilt it. Had block checked, heads and all...gaskets are correct, did test also to make sure no gases in coolant. No smoke. Runs great. Checked thermostat. I only went to electric fans cuz stock fan hangs about 3 inches below bottom of radiator after cv swap. I know the fans run slower the way i temporarily wired them up. Thats why im thinking airflow.

[Ranchero50]

When warm you should be able to feel an even change in temp from the top of the radiator to the bottom. If it's spotty, you have blockages in the radiator core. If it's not getting hot you have no flow. If the air coming from the fan is really hot you don't have enough air flow. If it's cold you don't have enough flow or it's not drawing through the core.

also, while troubleshooting temp problems make sure you timing isn't too advanced.

[rhyne]

Thanks yes the air from fans is really hot...i believe my timing is correct, not advanced...i need to find out the airflow its pulling now i believe.

[tnlprt]

Getting hot that fast sounds like
slow timing
lean fuel mixture
Head gaskets on backwards

Easy to check the head gaskets
Also easy to check the timing
Fuel mixture can be checked with a vacuum gauge

[colnago]

A few years ago, I had a similar problem. New radiator, new coolant hoses, and always on the edge of overheating after about 10 minutes. Finally took it all apart, and found that there was a rubber sleeve on the inside of the top hose. It had delaminated from the hose, folded over on itself, and was preventing the coolant from flowing. I removed this inner sleeve, cut it to be no longer than the upper metal radiator intake, and buckled it up. No problems since.

Joseph

[rhyne]

Im gonna check timing again. It was way advanced but i believe it correct and still have the issue. Flow is good. Gonna pick up an anemometer and check airflow.

[rhyne]

Update. Definately not getting good airflow. One fan alone is doing 1200 cfm. Not the rated 1750. Both fans together about 1300 combined. Hooked vacuum up for fuel mix and its off plus i suspect timing may retarded a tooth...so starting over...