Radiator Overheat.

Mudeblue

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New Griffin Radiator, new water pump, new serpentine belt set up, front and rear fans which together push 3,000 CF, 165 degree thermostat. Checked radiator flow in driveway with cap off. Appears good flow. Temp gauge at 215 degrees after 20-25 minutes, fans running and boiled over when car shut off as expected. Where to start?
 
If you filled it to the top, it will boil over. The solution is to either not fill it quite as much, or install a radiator overflow bottle.

Since it doesn't look stock with the aluminum radiator, the overflow won't look that out of place.
 
I’m wondering why the engine is hitting 215° when the thermostat is set for 165. What is putting so much heat into the cooling system?
 
I’m wondering why the engine is hitting 215° when the thermostat is set for 165. What is putting so much heat into the cooling system?
Did you verify the temp with a hand held temp gun?

When the rad cap is off you loose the pressure that increases the boiling point so when you shut the engine off it could boil especially if you are running a weak glycol solution.

In regards to the thermostat whether you put in a 165 or 190 doesn’t matter if your engine makes more heat. Once it passes that temp the thermostat is wide open. You could remove it and test it by placing it in a pot of water and slowly heat it up. Measure the point it opens.

First thing I would do is verify the temp with a hand gun, point the laser at the top of the thermostat. Make sure the cap is left on and see if it still boils then.

Get back to us with the results.
 
If you filled it to the top, it will boil over. The solution is to either not fill it quite as much, or install a radiator overflow bottle.

Since it doesn't look stock with the aluminum radiator, the overflow won't look that out of place.
John, not filled to top. Would expect it to overflow when I kill the engine. Given everything is new and I have flow, head scratcher? Fresh engine overhaul! Gasket problem?
 
Did you verify the temp with a hand held temp gun?

When the rad cap is off you loose the pressure that increases the boiling point so when you shut the engine off it could boil especially if you are running a weak glycol solution.

In regards to the thermostat whether you put in a 165 or 190 doesn’t matter if your engine makes more heat. Once it passes that temp the thermostat is wide open. You could remove it and test it by placing it in a pot of water and slowly heat it up. Measure the point it opens.

First thing I would do is verify the temp with a hand gun, point the laser at the top of the thermostat. Make sure the cap is left on and see if it still boils then.

Get back to us with the results.
Running to temp gauges. Boils over with cap on also. Top hose hard as a rock when hot indicating to me it is holding pressure and can’t escape fast enough through overflow. Not sure where to look for the problem?
 
The rad cap should be maintaining a pressure that’s why the hose is hard. Should be approximately 14 - 16psi depending on the system.
Again verify the temp.
 
What type of water pump did you go with, just a stock replacement or some "high flow" unit? Also the serpentine system does it state if it over/under drives the water pump and alternator?
 
The radiator isn't doing its job if it hits 215F (assuming that is an accurate temperature reading) after 20 minutes of idling. What did you pay for the radiator and what are its dimensions overall and number of rows of tubes?
 
When filling it, did you have the engine running and the heat on? Could be just an air pocket pushed its way out. When i say that i mean. If it cavitates at the water pump or t-stat. It'll sit there until the pressure in the system is high enough to force it out. I changed the water pump in a 97 Chevy k2500 years ago, the same happened to me. They are a bastard to get the air out. I see you live in Arizona so you may not even have the heat hooked up.
 
John, not filled to top. Would expect it to overflow when I kill the engine. Given everything is new and I have flow, head scratcher? Fresh engine overhaul! Gasket problem?

You mentioned an "engine overhaul." When this was done, was the engine block boiled and cleaned at the machine shop? If not, there could be a lot of crud in the coolant passages of the block. This would contribute significantly to an overheating problem.
 
The radiator isn't doing its job if it hits 215F (assuming that is an accurate temperature reading) after 20 minutes of idling. What did you pay for the radiator and what are its dimensions overall and number of rows of tubes?Griffin, Aluminum radiator, OEM specs.
You mentioned an "engine overhaul." When this was done, was the engine block boiled and cleaned at the machine shop? If not, there could be a lot of crud in the coolant passages of the block. This would contribute significantly to an overheating problem
You mentioned an "engine overhaul." When this was done, was the engine block boiled and cleaned at the machine shop? If not, there could be a lot of crud in the coolant passages of the block. This would contribute significantly to an overheating problem.
Yes.
The radiator isn't doing its job if it hits 215F (assuming that is an accurate temperature reading) after 20 minutes of idling. What did you pay for the radiator and what are its dimensions overall and number of rows of tubes?
Griffin,aluminum, three row, OEM.
 
New Griffin Radiator, new water pump, new serpentine belt set up, front and rear fans which together push 3,000 CF, 165 degree thermostat. Checked radiator flow in driveway with cap off. Appears good flow. Temp gauge at 215 degrees after 20-25 minutes, fans running and boiled over when car shut off as expected. Where to start?
Adding to my confusion, I have and put in the EXACT configuration in my 66 GTO, 389. It runs at 185 degrees and on a hot day here in Arizona, 195 degrees. Electric fans pushing 3,000 CF and set to come on at 185. Would expect the same for the Fury 383?
 
Not sure just what is causing your heat issues but I know most of those serpentine systems use an underdrive pulley running the water pump much slower. I put a March serpentine system on my 70 Challenger many years ago and that car never liked to idle long either. Never got hot while driving but 15 minutes in stop and go traffic always put the needle on H and made me run the heater on high. The other thing I wonder about it having a pusher and a puller fan. IMO, it don't get much better than a good thermo fan shroud combination.
 
Not sure just what is causing your heat issues but I know most of those serpentine systems use an underdrive pulley running the water pump much slower. I put a March serpentine system on my 70 Challenger many years ago and that car never liked to idle long either. Never got hot while driving but 15 minutes in stop and go traffic always put the needle on H and made me run the heater on high. The other thing I wonder about it having a pusher and a puller fan. IMO, it don't get much better than a good thermo fan shroud combination.
I have a pusher and puller fans and together they move 3,000 CF: part of the puzzle? Wonder if it would be possible to put a smaller pulley on the water pump because idling is worse but at temp's of 100+ here in Phoenix it may not be much help?
 
You could try one of these pumps before giving up on your underdrive pulley. It sounds like you have plenty of cooling but maybe the water is staying in the engine too long at idle. The coolant movement and the radiator have to work together to get the proper coolant temperature. Since your underdrive pulley is running slower, maybe the water is staying in the engine too long. I'm no scientist or engineer but it may be all it takes is to get a little more movement. MOPAR Big Block hi flow water pump
 
You could try one of these pumps before giving up on your underdrive pulley. It sounds like you have plenty of cooling but maybe the water is staying in the engine too long at idle. The coolant movement and the radiator have to work together to get the proper coolant temperature. Since your underdrive pulley is running slower, maybe the water is staying in the engine too long. I'm no scientist or engineer but it may be all it takes is to get a little more movement. MOPAR Big Block hi flow water pump
I will check it out.
 
Good luck getting it dealt with. Overheating is no good for us or our cars. Mine is pretty much all stock with no heat issues. I have a 22" radiator with a thermo clutch fan and shroud. I also have a screen in front of the radiator to keep the bugs out. I did notice the screen raises the temp a few degrees but not enough to cause problems.
 
I have a pusher and puller fans and together they move 3,000 CF: part of the puzzle? Wonder if it would be possible to put a smaller pulley on the water pump because idling is worse but at temp's of 100+ here in Phoenix it may not be much help?

I HOPE for your sake its just a crap radiator issue. Get a GOOD COPPER radiator if you can afford it. I run my rehabilitated 1965 Mopar 2524984, which does so well that I happily jumped at the chance to get another one from Florida for $300, then had the same shop rod and seal it. I ran just my FFD fan on it from December through April, 5 months, then bolted my 7 blade Mopar 2863215 18 inch fan onto the water pump for the hot season in Toostoned. I got a shroud w the deal in Florida, and yes, it helps pull a bit more air through, though I would nver have bought it without that primo old radiator attached.

Dollar for dollar, if I were to get an aluminum radiator again, I'd go to ECP and have them build one if they don't have one ready. I used one on Mathilda with good results until it got destroyed, but it cooled very well. Again, I ran a pusher and had built a custom box shroud for that one, which helped the mech fan in the summer.

I run a non-AC pump on my 383 now, with good results, and use a 180F RobertShaw thermostat. THOSE HELP! All thermostats are NOT created equal man. Like you, I've thought about using a smaller pully with the more common sorts of after market pump, but with a rebuilt old school non-AC one, I stick w the pully meant for those.

I suspect your radiator and thermostat aren't up to the job. Phx does get seriously hot, so I reckon you best fix this. Maybe a Flowkooler pump will do you good too. If I didn't have a nice horde of Old School non-AC pumps now, I'd try one of those.
 
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