Vintage Mustang Forums banner

1 - 20 of 55 Posts

·
Registered
Joined
·
29 Posts
Discussion Starter #1
Hi everyone,

you guys always help me. Thanks.

so I installed a new aluminum water pump and new 4row aluminum radiator with an electric fan in my 65v8.
It says cool cruising around town, but once I’m on the freeway after 20 min it starts to go over 200 degrees. I have an AOD tranny.
Any ideas? I checked the timing and it’s set to the book. I have a double pump Holley carb.
 

·
Registered
Joined
·
161 Posts
Keep in mind that 200 degrees F is NOT overheating. For many vintage Fords the thermostat is not fully open until 195 degrees F. Modern cars often hit 215-220 degrees F in normal operation. IF your cooling system is getting adequate air flow and water flow you may be worrying about nothing.
 

·
Premium Member
Joined
·
2,733 Posts
Sounds like the pump maybe cavitating at sustained higher RPM and not actually circulating the coolant. It's also possible that your lower radiator hose maybe collapsing and needs a stainless spring inside it to keep that from happening.
 

·
Registered
Joined
·
383 Posts
Was it overheating before or did it start after you changes a part?


Usually orderheating under a load with a gradual buildup of heat is a circulation problem. At work if a vehicle would run around town at normal temperature but the temperature increased at higher speeds or the temperature was fine until it started climbing a hill it was almost always a restricted radiator but since you have installed a new one that should not be the problem. Except for one time a new radiaotr screwed me. I got a radiator that the wrong tubes had been installed and they were too small.

At freeways speeds so much air is going through the radiator that it is almost always not an air flow problem. In my entire career I only saw one vehicle overheat at higher speeds from no air flow. It was a snow plow and the plow blade deflected the "all" of air away from the radiator. It was brand new truck, Ran perfect until the plow blade was hooked to it. I had to deliver it up to lake Arrowhead and it over heated the second I started to climb the mountain. I had to go back to the shop and remove the plow blade and stick in the bed of the truck.

Timing and air fuel mixtures will effect the temperature.

A Thermostat not opening all the way will be able to flow enough coolant at lower speeds but not enough at freeway speeds.

Like lee said, a lower hose collapsing because of no internal spring. Sitting in your driveway running it will look okay but it can collapse at higher rpms. That is the suction side of you water pump.

One that really messed with my head was a brand new water pump with a slipping impeller at high rpms. A Loose belt could do it but usually you will hear the alternator squealing before it is too lose to not turn the pump.

If it was head gasket leaking combustion into the coolant system it usually overheats all the time. There are test strips for checking that. We used the exhaust gas sniffer on the smog machine to test for CO2.

I'd try the lower hose first. See if when you squeeze it you can feel a spring inside of it
 

·
Registered
Joined
·
4,834 Posts
I smell a 180* t-stat that is letting it get to the run away stage.
Old lower hoses used to come with a spring, modern hoses are strong enough to not need a spring in them.
 

·
Registered
Joined
·
34,676 Posts
If it was doing it before the water pump & radiator change then my first guess would be insufficient spark advance. Your INITIAL advance might be "set to the book" but the advance at highway rpm and cruise vacuum might be insufficient, causing excess heat to be absorbed on the exhaust side of the head. Look at how much advance you are obtaining at that "highway rpm" and compare it to the specs... Dan Nolan @ The Mustang Barn does a good job at distributor re-curving as do some others. Obviously to be exact it'd be best done in conjunction with a dyno....
 

·
Registered
Joined
·
768 Posts
VFG has good points. A weak thermostat spring will start closing the tstat under high rpm. When was the last time you flushed your engine? The rear and lower head jackets have a tendency to collect crap, rust, etc. I swear by Thermocure by Evaporust. You can get it at walmart about $20. Dump an entire pint into your rad, start the car, run just enough to open the thermostat and get it through the system. Let it sit for several hours and then start it again and repeat 2 or 3 times. Best if you do it over 2 days with the fluid hot. When you dump to water, you will be shocked at the crud that comes out. This absolutely corrected most of my overheating issues. The other was goin from a 7" crank pulley to a 5.5" crank pulley, but that is a whole different story at 6K rpm.
 

·
Registered
Joined
·
4,834 Posts
...and if it starts getting hotter than you think it should after a while SLOW DOWN and let it recover some, don't exit and stop for Gods sake. Maybe you have crazy gears but no law says you have to run 75+ on the highway and with AOD you shouldn't be spinning more RPMs than just cruising around anyway.
Would you install a $7 195* or 205* t-stat to see the difference?


The WHAT?
I hope you can read that correctly. If he's surprised when it gets to 200 it must about never get there any other times. If you don't believe in thermal run away you might be a cool weather hippie.
I can't count how many times y'all might recommend a spring in the lower hose and it has NEVER solved the problem that I've seen. Search please and show me a thread here that says "ya, that spring solved my over heating issue." There is a single documented case from the last 20 years people like to point to of a Viper sucking its hose closed at high RPMs. Its a bigger scapegoat than vapor lock.
 

·
Registered
Joined
·
34,676 Posts
...and if it starts getting hotter than you think it should after a while SLOW DOWN and let it recover some, don't exit and stop for Gods sake. Maybe you have crazy gears but no law says you have to run 75+ on the highway and with AOD you shouldn't be spinning more RPMs than just cruising around anyway.
Would you install a $7 195* or 205* t-stat to see the difference?



I hope you can read that correctly. If he's surprised when it gets to 200 it must about never get there any other times. If you don't believe in thermal run away you might be a cool weather hippie.
I can't count how many times y'all might recommend a spring in the lower hose and it has NEVER solved the problem that I've seen. Search please and show me a thread here that says "ya, that spring solved my over heating issue." There is a single documented case from the last 20 years people like to point to of a Viper sucking its hose closed at high RPMs. Its a bigger scapegoat than vapor lock.
I've heard of thermal runaway related to batteries but never an automotive cooling system... regardless, what does that have to do with a 180* thermostat?
 

·
Registered
Joined
·
199 Posts
I have a 6 cyl. In my 65. Had the same problem. Redid the entire cooling system, new radiator, water pump, and even found the rare fan shroud and fan. Still overheated on the highway. I have a Holley 1bbl. Checked the jet size. Someone had installed a .048. Book said it needed a .063. Was running way too lean. No problems after changing to the correct size jet.
 

·
Registered
Joined
·
21 Posts
My money is on the tune of the engine, I have seen engines with rusted up rads run fine in 100+ heat, so there is def. more to the situation than just dumping more heat from the rad.
Lean fuel = Way hot. Even with a carb, I am considering putting in an O2 sensor to help me tune.
Timing, I usually need to retard an over heating engine, though I must admit, I had not considered retarded timing causing too much heat, but it makes sense that the unburned fuel will still be burning somewhere. Suppose most I see are already advanced up to detonation.
Do check idle and advanced, most people ignore the timing curve and wonder why the thing never runs right.

Have I added a spring and it fixed a heating problem?.. absolutely.
It was a big block truck, 100+ in Texas, new gates hoses... Watched it suck the hose closed in the driveway... never made same mistake again.

I think the 180 thermostat comment was tied to weak springs in the thermostat by groho.
Either way, the thermostat is a real possibility. I am about to try a flowcooler waterpump, might as well put one of their thermostats in too.

I really like the "clean the rust out" thoughts, some cylinders not getting the cooling due to rust could be causing havoc.

Oil delivery.... not sure how you check this out, but... the oil does a LOT to move heat around. That is why running heavier weight oil usually hurts the situation... design = 30 weight.
 

·
Registered
Joined
·
1,909 Posts
If you don't believe in thermal run away you might be a cool weather hippie.
I've heard of thermal runaway related to batteries but never an automotive cooling system...
Cool weather hippie checking in here...

Thermal runaway is a reactive phenomena caused by another source that adds heat at a rate greater than would normally be added. This could be a chemical or electrical reaction or instability. In the design of an automotive cooling system there are no outside variables to be introduced that would cause such a phenomena unless purposely done. I don’t know of any substances normally used in an auto (other than battery chemistry) which would cause a water/glycol mix to react in a way where thermal runaway would be a factor. If the coolant stream were polluted with fuel, oil, ATF or other auto fluids it would be a case of reduced cooling property as those fluids make the coolant less effiecient. Same with any rust or gunk that may be present in the cooling system.

The heat curve is more likely due to the saturation of the body to which the heat is being dissipated. IOW, just getting too damn hot. It’s typical second law of thermodynamics where for whatever reason the heat can’t be dissipated quick enough. My money would be on obstruction/reduced flow in the cooling system and/or tune issues generating more heat than desired.
 

·
Registered
Joined
·
4,834 Posts
Ok, i see I my have used a couple of $5 words when some 10 cent ones would have been better. I mean it just as when running without a thermostat can cause a car to run hotter. Each cycle the water makes is hotter and hotter until it exceeds the capacity to sufficiently remove heat.
 

·
Registered
Joined
·
29 Posts
Discussion Starter #18
If it was doing it before the water pump & radiator change then my first guess would be insufficient spark advance. Your INITIAL advance might be "set to the book" but the advance at highway rpm and cruise vacuum might be insufficient, causing excess heat to be absorbed on the exhaust side of the head. Look at how much advance you are obtaining at that "highway rpm" and compare it to the specs... Dan Nolan @ The Mustang Barn does a good job at distributor re-curving as do some others. Obviously to be exact it'd be best done in conjunction with a dyno....

I already ordered a spring for the lower hose. I have a 347 stroker with a double pump holley. I am going to buy a vacuum gauge. How can I best set the advance? WHat about my carb? Is it running to rich?
 

·
Registered
Joined
·
1,909 Posts
Ok, i see I my have used a couple of $5 words when some 10 cent ones would have been better. I mean it just as when running without a thermostat can cause a car to run hotter. Each cycle the water makes is hotter and hotter until it exceeds the capacity to sufficiently remove heat.
Negatory Big Ben, negatory. Running without a thermostat does not make an engine run hotter.
 

·
Registered
Joined
·
4,834 Posts
Rich=Cool
Lean=Hot
Negatory Big Ben, negatory. Running without a thermostat does not make an engine run hotter.
Running without a thermostat CAN make an engine run hotter.
And how did you know my locker room nickname?
 
1 - 20 of 55 Posts
Top