Author Topic: Cooling issues  (Read 313 times)

Zach

  • Active Forum Member
  • *
  • Posts: 182
Cooling issues
« on: May 15, 2025, 09:35:20 AM »
Recently put a new balancer in so it required me to drain and remove my radiator. Everything is assembled again. Trying to bleed the air out, parked on a incline, running car with cap off, antifreeze topped. Gets to operating temp and spills coolant out of cap, then proceeds to overheat past 220 before I turn it off. Letting it cool back down water in radiator is half full.This radiator used to stay pegged at 160 no matter the temp. Not sure why water isn't circulating through the engine. Wondering how you guys bleed your systems or at least troubleshooting steps you would take. Thanks.
1977 #s W72 400 4 Speed Trans Am
1971 351c 4 Speed Mustang Mach 1

b_hill_86

  • Oracle Forum Member
  • *
  • Posts: 2207
Re: Cooling issues
« Reply #1 on: May 15, 2025, 10:40:23 AM »
When I’ve filled mine back up after removing the engine I always leave the heater hose off the back of the head and fill the radiator till coolant comes out the back of the head. Not sure if that would help you but it’s worth a try.
-Brian-

1977 Trans Am 400 4 speed

Zach

  • Active Forum Member
  • *
  • Posts: 182
Re: Cooling issues
« Reply #2 on: May 15, 2025, 11:28:14 AM »
Took the thermostat off, engine was bone dry hopefully I didn't run it long enough to get too hot. Drilled two 1/8 bypass holes in thermostat for a fail safe / pressure relief. Also manually filled the engine just in case. Gotta let the housing rtv sit for a while before I try again.
Wondering if a new correct radiator is the right choice here, lower rad fitting is at a 30 ish degree angle makes it really tricky to get the lower rad hose on, I don't see it visually kinked and it has worked for 2 years, just don't know why this is an issue all of a sudden, and I dream about a drain valve...
« Last Edit: May 15, 2025, 11:50:27 AM by Zach »
1977 #s W72 400 4 Speed Trans Am
1971 351c 4 Speed Mustang Mach 1

rkellerjr

  • Oracle Forum Member
  • *
  • Posts: 6806
  • When you turn your car on does it return the favor
Re: Cooling issues
« Reply #3 on: May 15, 2025, 02:04:30 PM »
I've always done what you've done, put the car on an incline with nose up. Filled it up, leave cap off. start motor, when it gets hot I watch the coolant go down (thermostat is now open and cooling motor, if this doesn't happen, you have a bad thermostat) and then I fill it back up, repeat until it overflows. when it starts overflowing I put the cap back on then make sure the reservoir is full. 

Zach

  • Active Forum Member
  • *
  • Posts: 182
Re: Cooling issues
« Reply #4 on: May 15, 2025, 06:26:42 PM »
Well it seems to be OK as of right now idled fine in the driveway topped it off, drove it around the block quickly. Going to do a few full heat cycles and slowly add coolant just to make sure before I beat on it or go long distances, although I won't really know till it is a 90 degree day or hotter. My concern is my lower rad hose is slightly kinked on the inside cause of the aftermarket rad or my thermostat isn't opening all the way even though its 2 years old and was working 4 days ago before all of this.
1977 #s W72 400 4 Speed Trans Am
1971 351c 4 Speed Mustang Mach 1

Re: Cooling issues
« Reply #4 on: May 15, 2025, 06:26:42 PM »

Wallington

  • Oracle Forum Member
  • *
  • Posts: 2615
Re: Cooling issues
« Reply #5 on: May 15, 2025, 07:43:23 PM »
Heater works? Overflow bottle gets filled when hot and then siphoned back when cold? Does your lower hose have a spring in it to stop kinking, or being sucked in?

Zach

  • Active Forum Member
  • *
  • Posts: 182
Re: Cooling issues
« Reply #6 on: May 15, 2025, 08:54:25 PM »
Heater works? Overflow bottle gets filled when hot and then siphoned back when cold? Does your lower hose have a spring in it to stop kinking, or being sucked in?

I fear turning on my heater... but in theory it should still work I just don't want to found out if it doesn't. Overflow should work but I don't think its perfect, has the correct cap and fittings and such I just don't think is sucking and pulling like it should. Lower rad hose does have a spring and it doesn't looked kinked visually. Main issue is the after market radiator. It is a 4 row we got for free for some random car no idea what its original use case is we sort of just made it work original fan shroud still fits which is nice. The lower output is about 2 inches longer than stock and cuts in towards he fan a tiny bit which makes the lower rad hose not fit perfectly.
1977 #s W72 400 4 Speed Trans Am
1971 351c 4 Speed Mustang Mach 1

Wallington

  • Oracle Forum Member
  • *
  • Posts: 2615
Re: Cooling issues
« Reply #7 on: May 15, 2025, 09:21:16 PM »
Ok. A working heater confirms you have coolant at the of the engine/head/intake and not a pocket of air. More important with cars with heater taps than these with restrictor fittings. You aren't changing anything except the air ducting direction to see of its hot.

Bluebandit

  • Active Forum Member
  • *
  • Posts: 753
Re: Cooling issues
« Reply #8 on: May 21, 2025, 08:11:09 PM »
Can you trim off the lower hose. If not, try a visit to the parts store and look at their hoses, you may find one that's a closer fit.

Re: Cooling issues
« Reply #8 on: May 21, 2025, 08:11:09 PM »
You can help support TAC!