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Coolant flow problems

2K views 21 replies 6 participants last post by  64nailhead 
#1 ·
Yesterday my Small Block 350 suddenly overheat at idle. It has not had problems with overheating before.

I could see there was no flow through the system, through the radiator cap.

It had also emptied the cooler tank (the one on the right front tire)

I replace the thermostat, I thought it was stuck. It did not help.
The heating system in the car works fine, and both hoses a warm.
The lower radiator hose is NOT hot.
The upper radiator hose becomes warm (but you can easily hold it by hand)

I've had it running without radiatorcap, but it does not help.

The water in both the radiator and the manifold (at any rate what I can see) is fine liquid and not the least bit "mushy"

What am I doing from here?
- Remove thermostat and see if it changes anything?
- Remove both hoses from the cooler and flush it through with a garden hose
- burp system out (other method than to have the radiator cap off?)
- Drill a small hole in the thermostat to ensure constant review and eliminate thereby air?
- Other suggestions?

Good weekend :)
 
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#3 ·
Hmm, cant seemed to edit the previously post:
I was just out and try to leave it idle again. It be relatively quick warm (3 min = 90 degrees/180F) The temperature keep rising. I turned off the car at 110 degrees.
The inlet is as said not hot. and neither is the block. I can touch the exhaust manifold, and keep my hand there.

Heating hoses is warm and there is heat in the car, but I can easily keep my hands on them.

Do I have a broken gauge, or an air pocket at the sensor? The sensor sits in the cylinder head on the driver's side.

How can I measure the temperature in other ways?
 
#4 ·
engine

i'm kinda surprised even 3 minutes and u can hold the exh manifold.. more guts them me to grab it.. but 2 things. first do the drill the hole in the stat.. put the hole at 12 o'clock. next go to auto parts store (autozone has them) and get a new stat housing that has the pipe thread on top u can relocate your temp sending unit there.. a lot more accurate. then fill with water in case u need to drain again.. when your happy with end result then empty and refill with antifreeze.
 
#14 ·
I saw this same problem many years ago. Started engine and within just a couple minutes the temp was on it's way to the stratosphere. We checked everything and finally found the water pump shaft had sheared inside the housing. The pump was not moving the water but the shaft outside was spinning and looked fine. No noise, nothing. We pulled the pump thinking the inlet passage was clogged. When the pump was unbolted the impeller fell out.

New pump and back in business:cool:
 
#17 ·
The coil of wire in the lower radiator hose was placed in the hose at the factory to keep the it from collapsing when the coolant is vacuumed into the system on the assembly line. Radiator hoses do not need a coil of wire to keep them from collapsing after the coolant is installed on the assembly line. Replacement radiator hoses do not have a coil.

If you have a thermo controlled fan, the fan clutch is probably bad and needs to be replaced. The thermo controlled fan clutch will disengage at a predetermined temperature and remain engaged at 35% of the engine speed. If the fan clutch is bad, it will only stay engaged at a lower engine speed or not at all.
 
#19 ·
The coil of wire in the lower radiator hose was placed in the hose at the factory to keep the it from collapsing when the coolant is vacuumed into the system on the assembly line. Radiator hoses do not need a coil of wire to keep them from collapsing after the coolant is installed on the assembly line. Replacement radiator hoses do not have a coil.

l.
I've heard that before, but if it's true then why do the restoration businesses sell them if they're not needed.
THey work. Plain and simple!
Hurt nothing! Cost little to make and install.
 
#20 ·
The only radiator hose spring I have seen advertised was for a Ford Mustang. They actually may cause damage to the cooling system if the corrode and break up. Go buy a radiator hose at any parts store and it will not contain a spring.

Radiator hoses swell as the cooling system pressure increases, they don't shrink. Feel the upper and lower hose when the radiator is hot and the hoses will be as swelled up due to the pressure and as hard as a rock.
 
#21 ·
Well ... yestarday morning I was in the store and bought a ir thermometer, and a new temperature gauge and sensor. Ir meter shows fine temp around 82 degrees and all hoses become warm. The gauge in car shows 140 degrees. New sensor and gauge in the car and its still 140 degrees. Flushed entire system with the water hose. Still 140 degrees on the thermometer.

I tried tp put the gauge directly to the battery, and then the temperature was suddenly fine! I ended up finding out the gauge in the car had lost ground wire. New ground wire and everything is as usual! 6 hours of work to figure it out :-(

Anyone who is interested in a (nearly) new temperature gauge and sensor :-D
 
#22 ·
Glad to hear your problem is resolved, but it is a might bit unfortunate the the problem was corrected by a $40 tool. A heat gun is invaluable IMO, and for more issues than you were trying to resolve. At least you hadn't replaced every cooling system component to determine your had a wiring problem - PHEW!

Regarding your sensor, it's not a bad piece to have laying around to check other items - I'd keep it (I have two temp sensor/gauges setup for testing).
 
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