65 200 6 mustang running kinda hot

[JeffKeryk]

Originally Posted by user52165

Posting without reading the other posts is not a good idea.

Agreed. He posted it ran hot with or without the 'stat.

 

[faltic]

Originally Posted by ripcord

A very slightly blown head gasket can cause overheating without much in the way of other noticeable symptoms for a while. Test for combustion gasses from the radiator with a kit, or have a shop perform a test.



I was about tosugest this.

 

[philipp10]

Originally Posted by user52165
Originally Posted by philipp10
First off, are you sure the car used to run cooler? 194 does not seem much out of the ordinary. A quick check on Google says cars run 195-220.....that's why radiators have pressurized caps.

Most posters here are recommending bigger radiator, larger fans etc. But let's go back. At one time, not long ago, the OP stated, the car used to run cooler. So we have to assume, "something's changed". Starting from that assumption, the most logical path is to try and determine what has changed, not start changing parts. Since the car runs the same with no thermostat, you can eliminate that. You stated the radiator is been gone through, so all that's left (asuming the fan is running properly) would be to look at the amount of heat the engine is generating. Something has changed there. And running vinegar through the motor will not solve the issue. Your coolant is getting hot, so the transfer of heat from the block to the coolant is happening.

The second area to look is the flow of coolant through the system. Is there a blockage?

I would be looking at the vacuum advance some more or perhaps a slightly lean condition in the carburetor. I would also look closely at the hoses on the radiator for restricting flow of coolant.


Some of you guys have more egg on your face than the OP.

It is a 1965 car. "Google check says" .....................? Get serious, modern emissions cars run much hotter than old designs.

The OP found what he did wrong, corrected it, and posted it.

Posting without reading the other posts is not a good idea.

baloney. I had that exact same motor, many years ago. You could buy a 180 or a 195 for it. With the 180, it always ran close to 190, not much different than "modern cars". The laws of physics have not changed much since than.... I had thought the OP stated he tried running it without a thermostat. Guess I mis-read.

 

[eljefino]

If your radiator was 194' with the thermostat in backwards, you may not yet be out of the woods. I'd like to see it below thermostat temp so there's some reserve capacity.

 

[mattd]

I guess others have missed where's he removed the thermostat all together and still ran warm?

 

[Trav]

Its rare but I have seen a few that overheated with no thermostat.
The thermostat acts as a valve that basically slows the flow to the radiator, If coolant is not allowed to dwell in the radiator at some point all the coolant will boil at some point.
Normally a stuck open T stat will never reach operating temp and a stuck closed one will always overheat but under certain conditions a stuck open one will overheat.

Many times a track engine will not use a thermostat at all but instead a water outlet restrictor of various inside diameters to control coolant/radiator dwell time. Run it without one and it will boil over.

 

[philipp10]

Originally Posted by Trav
Its rare but I have seen a few that overheated with no thermostat.
The thermostat acts as a valve that basically slows the flow to the radiator, If coolant is not allowed to dwell in the radiator at some point all the coolant will boil at some point.
Normally a stuck open T stat will never reach operating temp and a stuck closed one will always overheat but under certain conditions a stuck open one will overheat.

Many times a track engine will not use a thermostat at all but instead a water outlet restrictor of various inside diameters to control coolant/radiator dwell time. Run it without one and it will boil over.

Trav I have to respectfully question the contention that the lack of thermostat would cause over-heating. What would br the mechanism to do that? The heat rejected by the radiator does not go down with no thermostat....does it?

 

[Jarlaxle]

Originally Posted by old1
Both. Does climb some when coming to an idle after running fast, but that is normal. Starting from cold, it warms to about 160+, therm opens, drops some, then over the next maybe 10 miles or so, at slow, or high speed,(60+). it will sloooowly climb to around 190/195. Generally holds there unless going to stop and go traffic.


Absolutely nothing is wrong...it's supposed to run 190-200 degrees. Use a 180 thermostat and don't worry about it.

 

[JeffKeryk]

Originally Posted by philipp10
Originally Posted by Trav
Its rare but I have seen a few that overheated with no thermostat.
The thermostat acts as a valve that basically slows the flow to the radiator, If coolant is not allowed to dwell in the radiator at some point all the coolant will boil at some point.
Normally a stuck open T stat will never reach operating temp and a stuck closed one will always overheat but under certain conditions a stuck open one will overheat.

Many times a track engine will not use a thermostat at all but instead a water outlet restrictor of various inside diameters to control coolant/radiator dwell time. Run it without one and it will boil over.

Trav I have to respectfully question the contention that the lack of thermostat would cause over-heating. What would br the mechanism to do that? The heat rejected by the radiator does not go down with no thermostat....does it?

My understanding is, water restrictors were used because at high rpm the water pump would force water hard enough to overcome the radiator cap pressure causing it to lose coolant. So overheating is not directly due to lack of a thermostat; rather a product of high rpm speeding up the water pump. That's my understanding; perhaps Trav can add his expertise.

 

[Trav]

Originally Posted by philipp10
Originally Posted by Trav
Its rare but I have seen a few that overheated with no thermostat.
The thermostat acts as a valve that basically slows the flow to the radiator, If coolant is not allowed to dwell in the radiator at some point all the coolant will boil at some point.
Normally a stuck open T stat will never reach operating temp and a stuck closed one will always overheat but under certain conditions a stuck open one will overheat.

Many times a track engine will not use a thermostat at all but instead a water outlet restrictor of various inside diameters to control coolant/radiator dwell time. Run it without one and it will boil over.

Trav I have to respectfully question the contention that the lack of thermostat would cause over-heating. What would br the mechanism to do that? The heat rejected by the radiator does not go down with no thermostat....does it?


This is what Moroso says..

Limiting the amount of coolant flow leaving the engine lets you control the amount of heat absorbed by the coolant itself. You can adjust the flow with one of these Moroso water outlet restrictor kits. They include include three round aluminum plates with 5/8 in., 3/4 in., and 1 in. i.d. holes. Simply mount the appropriate plate under the water outlet on the intake manifold. An easy and economical temperature control solution!

Originally Posted by JeffKeryk
My understanding is, water restrictors were used because at high rpm the water pump would force water hard enough to overcome the radiator cap pressure causing it to lose coolant. So overheating is not directly due to lack of a thermostat; rather a product of high rpm speeding up the water pump.


This was true on mid 50's Chevy small blocks but on later radiator designs not. Pressure is a direct result of heating of the coolant, not being a positive displacement pump even a high flow pump will not generate pressure of any significant amount without expansion of the fluid..

Quote
Water pumps are not positive displacement pumps. The water pump is a centrifugal pump that can move a large volume of coolant without increasing the pressure of the coolant


Having gone through all that let me share my own experience.
In a normal street engine with a properly sized radiator (stock is usually adequate for the stock engine) running without a thermostat will not allow the engine to overheat, in fact just the opposite it will probably never get to normal operating temp under most circumstances.

When you throw something into the mix like high ambient temps, a radiator that is undersized for some reason (usually engine tuning) or a bottom breather missing the underbody deflector shield(s) and high revs for an extended time this can be a real problem. The coolant will not remain in the radiator long enough (dwell) for the air going over the fins to remove the heat. Once the coolant temp reaches a point it will run away and boil over.

 

[JeffKeryk]

Sorry, I ain't buying the radiator dwell time.
More radiator dwell time results in lower outlet temperature per unit.
If you double the flow rate, you effectively halve the temperature differential across the cooler.
A smaller temperature differential across the cooler means that the average coolant temp will drop closer to ambient air temperature.
Effectively, you are moving more heat toward cold until you reach ambient temperature.

This assumes sufficient radiator efficiency and other things (air flow, air temp) being equal.

 

[edhackett]

Originally Posted by JeffKeryk
Sorry, I ain't buying the radiator dwell time.
More radiator dwell time results in lower outlet temperature per unit.
If you double the flow rate, you effectively halve the temperature differential across the cooler.
A smaller temperature differential across the cooler means that the average coolant temp will drop closer to ambient air temperature.
Effectively, you are moving more heat toward cold until you reach ambient temperature.

This assumes sufficient radiator efficiency and other things (air flow, air temp) being equal.


The rate of temperature transfer is driven by the temperature differential. The greater the differential, the more heat that can be transferred in any given time. You want as high as practical differential between the engine and radiator tubes, and radiator tubes and air to remove the most heat. The colder the return flow, the faster the engine can transfer heat to the coolant. If you halve the temperature differential, you reduce the amount of heat that can be removed from the system on each circuit.

https://byjus.com/physics/fouriers-law/

Ed

 

[Trav]

I saw a demonstration put on by a large diesel truck manufacturer in the 80's that showed the temps going in and coming out of the radiator at different flow rates, more time in the radiator (to a point) with the same CFM airflow over the fins resulted in a cooler temp of the fluid at the cooler outlet.
An engine thermostat is nothing more than a variable restriction that even when fully opened is a relatively small opening compared to the size of the housing.

 

[JeffKeryk]

Originally Posted by edhackett
Originally Posted by JeffKeryk
Sorry, I ain't buying the radiator dwell time.
More radiator dwell time results in lower outlet temperature per unit.
If you double the flow rate, you effectively halve the temperature differential across the cooler.
A smaller temperature differential across the cooler means that the average coolant temp will drop closer to ambient air temperature.
Effectively, you are moving more heat toward cold until you reach ambient temperature.

This assumes sufficient radiator efficiency and other things (air flow, air temp) being equal.


The rate of temperature transfer is driven by the temperature differential. The greater the differential, the more heat that can be transferred in any given time. You want as high as practical differential between the engine and radiator tubes, and radiator tubes and air to remove the most heat. The colder the return flow, the faster the engine can transfer heat to the coolant. If you halve the temperature differential, you reduce the amount of heat that can be removed from the system on each circuit.

https://byjus.com/physics/fouriers-law/

Ed

That is for a given unit of coolant. As flow increases, overall coolant temperature will become closer to ambient temperature. Not just the unit leaving the radiator.
More overall heat will be transferred to the atmosphere.

 

[JeffKeryk]

Originally Posted by Trav
I saw a demonstration put on by a large diesel truck manufacturer in the 80's that showed the temps going in and coming out of the radiator at different flow rates, more time in the radiator (to a point) with the same CFM airflow over the fins resulted in a cooler temp of the fluid at the cooler outlet.
An engine thermostat is nothing more than a variable restriction that even when fully opened is a relatively small opening compared to the size of the housing.

The radiator outlet is a given unit, not the average coolant temperature.

 

[Trav]

From Moroso...

Quote
These Restrictors are used in place of the thermostat to reduce the speed of water flowing through the engine block for more efficient cooling. Restricting the flow of water leaving the block lets you control the amount of heat that's absorbed into the water. Because radiators and water pump pulleys are sized differently for each engine, you will need to experiment with each Restrictor Plate to determine the amount of flow reduction needed. To obtain the desired cooling system temperature, the Restrictor Plates are packaged with 5/8", 3/4", and 1" openings. One should suit your particular application.P/N 63440 WATER OUTLET RESTRICTOR KIT Fits: All Chevy V8, V6 and Small Block Ford V8 Engines Kit Contains: (3) Restrictor Plates with 5/8", 3/4", and 1" openings.

 

[JeffKeryk]

Originally Posted by Trav
From Moroso...

Quote
These Restrictors are used in place of the thermostat to reduce the speed of water flowing through the engine block for more efficient cooling. Restricting the flow of water leaving the block lets you control the amount of heat that's absorbed into the water. Because radiators and water pump pulleys are sized differently for each engine, you will need to experiment with each Restrictor Plate to determine the amount of flow reduction needed. To obtain the desired cooling system temperature, the Restrictor Plates are packaged with 5/8", 3/4", and 1" openings. One should suit your particular application.P/N 63440 WATER OUTLET RESTRICTOR KIT Fits: All Chevy V8, V6 and Small Block Ford V8 Engines Kit Contains: (3) Restrictor Plates with 5/8", 3/4", and 1" openings.



Got it. Not sure I can follow their logic from a thermodynamics standpoint.
All good.

 

[edhackett]

Originally Posted by JeffKeryk
Originally Posted by Trav
From Moroso...

Quote
These Restrictors are used in place of the thermostat to reduce the speed of water flowing through the engine block for more efficient cooling. Restricting the flow of water leaving the block lets you control the amount of heat that's absorbed into the water. Because radiators and water pump pulleys are sized differently for each engine, you will need to experiment with each Restrictor Plate to determine the amount of flow reduction needed. To obtain the desired cooling system temperature, the Restrictor Plates are packaged with 5/8", 3/4", and 1" openings. One should suit your particular application.P/N 63440 WATER OUTLET RESTRICTOR KIT Fits: All Chevy V8, V6 and Small Block Ford V8 Engines Kit Contains: (3) Restrictor Plates with 5/8", 3/4", and 1" openings.



Got it. Not sure I can follow their logic from a thermodynamics standpoint.
All good.


This is the way I see it: Rate x Time = Heat transferred. You also have to account for the thermal conductivity of the radiator and block materials, which is also rate. It takes time to transfer the heat from the inside of the radiator tube to the outside of the tube and then to the fins. Increasing time (and/or rate) results in more heat being transferred.

Ed