Cooling confusion

[KevinT 10]

Here's what I have:

69 vert

mild 302 with a/c (sanden conv.), aod

new 3+ row radiator from npd (20")

the electric fan and shroud kit from npd

10" electric pusher fan on the a/c condensor

new high flow 180* thermostat

recent flush of radiator/cooling system

new fluid, 33% anti-freeze & water wetter

new radiator cap

coolant overflow tank

 

Here's my problem:

In the high temps (98-103 lately) we have here in Arkansas, I have had trouble controlling the temps in my car. The temp will slowly creep up and doesn't seem like it will stop. Since the flush and new fluid it has been much better, but still gets to 210 and climbing. I haven't driven it for much more than 30 min or so at a time, but it doesn't seem like it will stop rising.

 

Here's where I am getting confused.

It seems logical that with a cooling problem that temps would rise at idle in traffic since there isn't as much airflow, but the temps also seem to rise when cruising at 70 mph on the interstate. The car seems to do the best job cooling in the 30-50mph range. Above or below that temps seem to climb. I would have thought that the higher speeds would help with the cooling more.

 

I have spent a bunch of time getting the timing right, so I don't think that is part of the problem anymore, and I can see the tabs at the front of the heads, so I don't think the head gaskets are installed backwards. The water pump hasn't been changed since I got the car 18 months ago, but seems to be flowing fine.

 

Any suggestions??

[KevinT 10]

Here's what I have:

69 vert

mild 302 with a/c (sanden conv.), aod

new 3+ row radiator from npd (20")

the electric fan and shroud kit from npd

10" electric pusher fan on the a/c condensor

new high flow 180* thermostat

recent flush of radiator/cooling system

new fluid, 33% anti-freeze & water wetter

new radiator cap

coolant overflow tank

 

Here's my problem:

In the high temps (98-103 lately) we have here in Arkansas, I have had trouble controlling the temps in my car. The temp will slowly creep up and doesn't seem like it will stop. Since the flush and new fluid it has been much better, but still gets to 210 and climbing. I haven't driven it for much more than 30 min or so at a time, but it doesn't seem like it will stop rising.

 

Here's where I am getting confused.

It seems logical that with a cooling problem that temps would rise at idle in traffic since there isn't as much airflow, but the temps also seem to rise when cruising at 70 mph on the interstate. The car seems to do the best job cooling in the 30-50mph range. Above or below that temps seem to climb. I would have thought that the higher speeds would help with the cooling more.

 

I have spent a bunch of time getting the timing right, so I don't think that is part of the problem anymore, and I can see the tabs at the front of the heads, so I don't think the head gaskets are installed backwards. The water pump hasn't been changed since I got the car 18 months ago, but seems to be flowing fine.

 

Any suggestions??

[S code 69 13]

Since everything is new and the only real modification that might cause a problem is your fan system that would be my first consideration. some of those electric fans don't move anywhere near the volume of air a real fan does.

[S code 69 13]

Since everything is new and the only real modification that might cause a problem is your fan system that would be my first consideration. some of those electric fans don't move anywhere near the volume of air a real fan does.

[d.reese 13]

The High Flow T-Stat? Why are you street or race the engine?

 

Try a stock 180 deg. You'll find that if the water is not restricted enough in any block, it will cavitate the back of the motor of water. ( sucking the rear of the motor dry).Thus causing rizing temps at speed. Only drag cars run the high flow or remove the stat cause of the short burst of engine operation or they are running alcohol for fuel which is a coolant by its self. They can get away with out one.

 

Try it and see if it works.

 

On circle track cars they run a reduction pulley on the water pump for the same reason. Too much flow starves the rear of the block! Causing sever over heating.

[d.reese 13]

The High Flow T-Stat? Why are you street or race the engine?

 

Try a stock 180 deg. You'll find that if the water is not restricted enough in any block, it will cavitate the back of the motor of water. ( sucking the rear of the motor dry).Thus causing rizing temps at speed. Only drag cars run the high flow or remove the stat cause of the short burst of engine operation or they are running alcohol for fuel which is a coolant by its self. They can get away with out one.

 

Try it and see if it works.

 

On circle track cars they run a reduction pulley on the water pump for the same reason. Too much flow starves the rear of the block! Causing sever over heating.

[KevinT 10]

Thanks for the input. I will try another new thermostat since several people say they are prone to inaccuracy even right out of the box. I will take your advice and try a normal one to see if that helps. That fan sure seems to move alot of air so I'm not ready to give up on it yet.

[KevinT 10]

Thanks for the input. I will try another new thermostat since several people say they are prone to inaccuracy even right out of the box. I will take your advice and try a normal one to see if that helps. That fan sure seems to move alot of air so I'm not ready to give up on it yet.

[d.reese 13]

A lot of fan is a good thing, but the water moving to fast threw the radiator keeps it from being able to cool the water down.

[d.reese 13]

A lot of fan is a good thing, but the water moving to fast threw the radiator keeps it from being able to cool the water down.

[jerry69 10]

Just another direction... are you running a new after market water temperature gauge? If so a is it mechanical or electrical sensor.... I've been seeing a lot of electrical water temperature gauges fail recently.... If you have a friend who has one of those lazer heat reading gun see if you can borrow it and get the car heated up and take your readings.... I just finished working on a custom 3 wheel trike with a 350 and the temp would go between 210 and 225 at 70 mph and no over flow, I took the heat gun and and while the guage read 225 I got readings of 185 around the entire radiator, hoses and thermostat cover, problem was the electrical water temp gauge was failing (OHMS), the sensor had been replaced twice by the owner and then he got confused.....

[jerry69 10]

Just another direction... are you running a new after market water temperature gauge? If so a is it mechanical or electrical sensor.... I've been seeing a lot of electrical water temperature gauges fail recently.... If you have a friend who has one of those lazer heat reading gun see if you can borrow it and get the car heated up and take your readings.... I just finished working on a custom 3 wheel trike with a 350 and the temp would go between 210 and 225 at 70 mph and no over flow, I took the heat gun and and while the guage read 225 I got readings of 185 around the entire radiator, hoses and thermostat cover, problem was the electrical water temp gauge was failing (OHMS), the sensor had been replaced twice by the owner and then he got confused.....

[Pakrat 1,043]

Make sure you don't have any air in the system either. Sometimes when people purge and flush the system they trap air in it during refill and it suddenly starts to run hotter than it did before the flush.

[Pakrat 1,043]

Make sure you don't have any air in the system either. Sometimes when people purge and flush the system they trap air in it during refill and it suddenly starts to run hotter than it did before the flush.

[d.reese 13]

Good point Pak, we have allways jacked up the front of the car so the radiator was the highest point on the water fill, this will get all the air out. Crank and warm, then fill!

[d.reese 13]

Good point Pak, we have allways jacked up the front of the car so the radiator was the highest point on the water fill, this will get all the air out. Crank and warm, then fill!

[bnickel 10,004]

since you have ac and a heat producing AOD you really need to step up to a 24" radiator instead of the itty bitty 20" one. i doubt that replacing the hi-flow stat is going to help ant at all, in fact in most cases it will help a lot. you really aren't moving that much more water through the engine you are really just getting all the hot water out so cooler water can flow in behind it if you are running a stock pump and pulleys.

[bnickel 10,004]

since you have ac and a heat producing AOD you really need to step up to a 24" radiator instead of the itty bitty 20" one. i doubt that replacing the hi-flow stat is going to help ant at all, in fact in most cases it will help a lot. you really aren't moving that much more water through the engine you are really just getting all the hot water out so cooler water can flow in behind it if you are running a stock pump and pulleys.

[Justafordguy 10]

I had the same thing happen when I installed the AC on mine. I ended up getting a larger aluminum radiator. It never goes over 180 now and it gets really hot here in Florida.

[Justafordguy 10]

I had the same thing happen when I installed the AC on mine. I ended up getting a larger aluminum radiator. It never goes over 180 now and it gets really hot here in Florida.

[jag 10]

Whats the condition of your heater core? I always ran hot and then the heater core went out. i put a new core in and it runs much cooler. The core can be a big restriction as it gets older.

JAG

[jag 10]

Whats the condition of your heater core? I always ran hot and then the heater core went out. i put a new core in and it runs much cooler. The core can be a big restriction as it gets older.

JAG

[jgstang 21]

justafordguy, i'm still thinking on what rad to get for my 69 so if you don't mind could you post some pics of your rad and let us know what size etc it is.sounds like your motor runs nice and cool in the heat! i've been shopping around and seems to me that theres not to many aluminum rad's out there that will fit a 69 nice without cutting things! thanks

[jgstang 21]

justafordguy, i'm still thinking on what rad to get for my 69 so if you don't mind could you post some pics of your rad and let us know what size etc it is.sounds like your motor runs nice and cool in the heat! i've been shopping around and seems to me that theres not to many aluminum rad's out there that will fit a 69 nice without cutting things! thanks

[KevinT 10]

Well, I did another flush, new thermostat with a 1/8" hole drilled in the outer lip to aid in bleeding air out of the system (suggested on several websites I had been looking at). The heater core and all of the a/c stuff is new. I haven't had too much of a chance to check it since I did all of that, so while it seems a little better, I won't know for sure until I get a few more miles on it. I'm hoping I can solve this problem without replacing the radiator since I have an electric fan and shroud designed for the 20" one and the expense of a new radiator and fan set-up is out of the question for now. Just getting it on the road this spring was a hair-raising, wallet-draining, experience with a lot of dirty looks from the wife every time a new box from NPD arrived.

 

Would a new water pump, possible a flow-kooler, help at all?