Overheating on highway

[SkippyMus]

Hey guys, as a lot of others my pony heats up, but the thing that puzzles me is mine even does it on the highway.
It's a 65 with a 289, standard fan, its got an ok 3 core radiator which I recently pulled out and sent off for a clean, and recently added a shroud which barely did a thing.
I'm thinking of getting a new alloy radiator with an electric thermo fan but think I must be missing something silly.
I don't get it. Ideas?

[EXHAUSTED]

Did you replace the thermostat & radiator cap when you did the radiator? Is your temp gauge reading correctly? Use an infra red heat sensor to check what the temp is.

[evan]

Check timing.

Evan.

[1966stang]

Check timing.

Evan.

yep, also check you don't have a head gasket problem.

I take it you have fitted a debris filter to your top hose as those motors flake off rust and result in blocked radiator though if yours has been recently cleaned it may not be the problem

Just my 2c worth

Greg 

[SkippyMus]

I don't have a debris filter yet but did just read about it yesterday so that's something I'll have to look into.
I haven't done the thermostat but it does open up fully but not sure if the temp range is correct, what degree thermostat do you guys recommend?
I don't trust the guage too much but it has boiled over before so it is overheating. :$

[R_Beckhaus]

Sender unit could have carped itself, giving the impression of overheating
cheers, Ron B

[Salthorse]

My repair manual states that the T'stat should open at 86 to 91 and be fully open at 100.

Dave

[shaunp]

Timing, make sure the vacuum advance is working, not only does this effect fuel comsumption but also temp at cruise. They need a 5 blade fan, but at highway speed the air flow should be plenty. Before you get too carried away get it hot then check the temp an infared thermometer, it may not be hot at all.  Get it hot pull up and shine the temp gun at the thermostat housing, you can also check the temp drop across the rad inlet and out let.
My Discovery would go to super hot on the guage and start blinking the warning light. When I checked the temp though it was hardly even getting hot enough to open the thermostat. It had a bad earth, the engine and dash had a different earth potenial of 1.5V, so the dash gauge was reading wrong.
It could simply be that the dash voltage regulator is toast, or the alternator reg is, and at constant high speed the guage can't handle the voltage from a high out of a crook reg.
So check the gauge is working properly first, get hold of a temp gun.

[ponyride]

I don't trust the guage too much but it has boiled over before so it is overheating. :$

Has it boiled over only, or is the temp gauge showing that it's overheating? If the gauge reads that it's not too hot but it loses coolant, you may have too much in the radiator. If you overfill it (ie to the top) it will spit it back out when it gets hot.

[SkippyMus]

It was definitely boiling I could hear it and the gauge showed hot and cool and was overflowing. Quiet traumatic :$ :p

[1966stang]

Have you got the correct pressure and size radiator cap? Is the thermostat installed correctly? If it's the wrong way round it will definitely boil.

Are your radiator hoses collapsing, in particular the bottom hose.

Greg

[Macka]

If its only overheating when you are on the highway it is not a water pressure or air flow problem.  It will be a circulation problem.  If everythings been cleaned out it will more than likely be a hose closing up on you. 

Get it up to temperature and inspect under the bonnet with the engine running, give it some good revs to match what you'd be doing out on the road and check that the bottom hose isn't squeezing up stopping flow of water.  It will do this if the springs have rusted out in your hose and because the enigine is sucking at the bottom, it creates too much and  pulls the hose in creating the flow problem.  Hence the over heating as the engines not getting enough coolant.

Fitting an extra 12V fan is good value, but only for extended stopping situations.

[shaunp]

If the heads have been off the gaskets could be backwards, could be the bottom hose.

[GLENN 70]

Shaun can you put windsor gaskets on backwards ,i know you can on a clevo and that causes overheating problems right away .Check bottom hose ,timing and its not running lean at cruising speeds .No matter what fan you run wont stop heating problems over 60klms per hr .Some electric fans cause heating problems at that speed when not working stopping air going through radiator .Even some cals stop air flow and need flapper panels fitted .Make sure you are running a themostat ,not running one will cause the water to flow to fast and not cool down at hwy revs .

[ANGZ66]

The head gaskets can be something else to check for.

Roger.

[GLENN 70]

Same as a 302/351c ,you can check the front of gasket outer edge is sitting out .This will cause it to over heat all the time ,not just on hwy driving .If you check 302/351 gaskets the water holes are large and at front ,putting gaskets on backwards causes big heating problems .

[Moz]

Just a thought,

Is the Thermostat in backwards?
or is it even opening, what temp thermostat is in it?

I am running a 160F Thermastat
double 1inch core Aluminium Radiator with flexi fan
and a 16inch Thermo fan which kicks in at 190F

Friday night went for a drive to the beach (St. Kilda) and it was constantly on,
outside temp was 30C

Moz

[Meaty0]

Ahaa!  We had a similar problem too!  I suspected the thermostat but to be sure, I just simply removed it and took the car out for a spin.  No overheating at all, so I put in a new thermostat and problem solved.   I would also check your timing, and also - make sure the water jackets are flushed out.  Mine was pretty clogged.

[Salthorse]

You can check your T'stat by putting it into a saucepan and watching when it opens as the water get hotter. You can check the water temp by using a milk frother thermo or a meat thermo. My 160 started to open at around 85 and was fully open when the water boiled. Conclusion: Thermostat was OK.

Cheers

Dave

[GLENN 70]

You have to run a themostat ,1st it brings the temp up quickly to running temp ,2nd will open and close to keep temp right , 3rd slows down water flow  through radiator .By not running a themostat the engine will run cooler for quite a while but will get hot and not cool down . A cold engine is not good must run at a temp for the oil to be right and will run rich .160 to 190 deg is normal .

[SkippyMus]

I just noticed my fan is not a 5 blade but a 7 blade. Would this make a difference? I have seen a couple of people say they "Need a 5 blade"

[GLENN 70]

7 is better than 5 ,also the fan works up to around 60 kph then its air flowing in by itself . I would try a new themostat ,but before fitting it i would pull the guts out of the old one and give that a go .As i said before you should run one otherwise the water flow through the engine and radiator will be to fast and water in radiator wont have time to cool down . Mustangs and older cars do have over heating problems ,new cars run around 190 to 200 deg .I have tested my mustang with my heat gun and it runs at 190 .

[SkippyMus]

Ok so after now putting some new life into the pony with a new 570 holley, weiand intake, electronic dizzy and large alloy radiator. As well as checking timing. Took the car for a little 20min drive down the highway for the first time after all the mods. What happens. Same problem. Boiled and coolant everywhere. :$ not fun.
Anymore ideas???

[shaunp]

If it only does it on the highway, discount the fan & shroud etc, plenty of air flow at highway speed, and look at bottom hose, does it have a spring in it to stop it collapsing, timing, cap , thermostat, put a 160 in it,  is the water pump cavitating  etc. This is before you worry about engine issue, but you could get the water tested to see if has any exhaust in it. An alloy rad won't fix it if the rad is not the issue, there is nothing wrong with brass ones.

[EXHAUSTED]

Did you purge the system of air??