Overheating 66

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Offline FickleLife

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Overheating 66
« on: October 30, 2019, 11:36:06 AM »
Overheating, that old chestnut.

I have a 66 302 that overheats in traffic. In normal driving with air running though the grille, it normally it sits at just under half on the gauge (I know the gauge is not a reliable measure) and putting the temp laser gun on it I have confirmed that this is at 180 deg. It can start to overheat when stationary on a fairly mild day, low 20s depending how long you're in traffic. I took it out on a 28 deg day last week and in traffic it started to creep up approaching 3/5ths. I pulled over and put the temp laser gun on it and it recorded

lower hose 166
block just before thermostat housing 196
thermostat housing 187
upper hose just after thermostat housing 189

If I sit longer in traffic the gauge can get to 4/5th, but I 've never taken it past there

Things I've done to attempt to remedy the situation

1) Aluminimum rad https://www.custommustangs.com.au/2-row-aluminum-radiator-5.0
2) new thermostat 180deg which works as tested in boiling water before it went in
3) 7 blade flex fan https://www.flex-a-lite.com/belt-driven-fans/17-inch-7-blade-silver-flex-fan.html
4) 3 inch shroud

The fan seems to be pulling good air through the rad - a piece of paper at idle gets sucked to the front of the rad, but not sure if 166 deg on the return hose is cold enough to stop overheating? The shroud could be better, there's air gaps around it so it is not flush to the rad... not sure how much of a difference this would make though in the grand scheme as it's already a beast of a shroud. 

Assuming the rad itself is ok, this leaves me with a couple of things to do (in order of how I think I should tackle them)

a) flush the block, that said the coolant and rad is clean. I don't know what sludge may be in the engine inhibiting its cooling performance. What would be the most effective way to flush?
b) new water pump, the one on there is a zillion years old. It could be that not enough coolant is moving around. I have heard that there's a balance to be struck, not enough flow and the engine overheats, too much flow and the coolant doesn't have time to cool in the rad. Is there any truth to this as I would have thought the thermostat is also there to regulate flow making too much flow moot.
c) elec thermo fan to really suck the air through when stationary, would prefer to not do this but if it has to be done fair enough

What does the collective wisdom of the forum recommend? Thanks


« Last Edit: October 30, 2019, 11:38:06 AM by FickleLife »

Offline GLENN 70

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Re: Overheating 66
« Reply #1 on: October 30, 2019, 12:28:55 PM »
What size is the radiator ? Bigger than the original small 66 I hope . Where does the fan / fan blades sit in the shroud ? .  What sort of fan is it ? .  A new water pump would be a good idea . What the timing set at ? Might even be running lean , what carb ?

Offline barnett468

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Re: Overheating 66
« Reply #2 on: October 30, 2019, 12:59:37 PM »
What size is the radiator ? Bigger than the original small 66 I hope .

It's a scott drake with two 1 inch deep rows, so it has the coolant capacity of at least a stock 3 row rad.

« Last Edit: October 30, 2019, 01:01:32 PM by barnett468 »

Offline barnett468

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Re: Overheating 66
« Reply #3 on: October 30, 2019, 01:06:24 PM »
What rad was in it before?

Can you post a photo thru the filler hole of the tube size of both rads?

Is there vacuum going to your distributor vacuum advance can at idle?

How much gap between the fan and the shroud?


If your ignition timing is not optimal for your particular engine, it can cause it to run hotter than normal.

A high flow pump like a flowkooler will certainly not hurt, and yours may have impellers that have been eaten away some which is uncommon but it does happen. No way to tell unless you remove it.

A high flow brass t stat like a milodon should be used in either case with or without a high flow pump whenever the rad size is increased, but it is more important when a high flow pump is used.

Don't loose sleep thinking about how the flow speed affects the cooling, because it will never flow too quickly if a t stat is used.

.

« Last Edit: October 30, 2019, 01:13:30 PM by barnett468 »

Offline Micks66coupe

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Re: Overheating 66
« Reply #4 on: October 30, 2019, 03:10:41 PM »
I thought the temp figures you quoted for a warm day in slow traffic were ok?

Our 66 runs at around 170deg highway speeds and around town 180-195deg, stock motor/radiator (reconditioned) and factory fan. Only additions are a recovery tank and I fitted an auxillary electric Autometer temp gauge, I left the factory sender unit connected to the factory dash and the Autometer sender is in the thermostat housing.

Offline barnett468

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Re: Overheating 66
« Reply #5 on: October 31, 2019, 04:44:28 AM »
I thought the temp figures you quoted for a warm day in slow traffic were ok?

The recorded temps were with his temp gauge at "3/5", he did not record the temp when it was at "4/5".

Ideally, the temp should never get higher than around 7 degrees f above the t stat rating, and this is achievable...if one has usually enough money.

"I took it out on a 28 deg day last week and in traffic it started to creep up approaching 3/5ths. I pulled over and put the temp laser gun on it and it recorded

lower hose 166
block just before thermostat housing 196
thermostat housing 187
upper hose just after thermostat housing 189

If I sit longer in traffic the gauge can get to 4/5th, but I 've never taken it past there"

Offline shaunp

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Re: Overheating 66
« Reply #6 on: October 31, 2019, 08:49:45 AM »
I dont think its getting too hot really 180-190 is ok. 190 is 87C  pretty close to the thermostat I'd say. you could try a 74 in it. Not sure there is anything wrong It wont boil till it gets to 120 with a 15 pound cap, and if you have good coolant boiling point will be well over 130. Could try a high flow thermostat.

Offline FickleLife

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Re: Overheating 66
« Reply #7 on: November 11, 2019, 06:16:45 PM »
Ok, today is 29 deg, Iíve been stuck in traffic, it hit 4/5ths (pointing just past the P in TEMP) and I pulled over and took the readings

Hereís some pics of the rad, shroud and fan https://imgur.com/gallery/hbD9uEt

lower hose 178
block just before thermostat housing 215
thermostat housing 207
upper hose just after thermostat housing 207
Rad cap 158

It has a 13psi rad cap

Some thoughts
- when I get going after being stationery, temp bumps up a smidge and then drops over a min or two as the air flows through the rad and water is moving faster. Could this be the pump is a little knackered as the water is not flowing fast enough when stationary as the temp bump seems to be the hot water sitting in the block too long hitting the sensor just near the thermo stat housing?
- When stationary, the water coming out of the rad is still 180 so not enough air being pulled through - thermo fan?

My current thinking is to replace the fan with a good 16 inch thermo and a shroud (that hopefully comes with it) that covers all the area of the rad. I am hoping that the raw airflow will solve any water pump issues that may be there. Or am I looking at this backwards? It does have a beast fan on it already.

Fan is about 15-20mm from the rad. Shroud contains the whole fan. There are gaps around the shroud. Pics are in link above 

« Last Edit: November 11, 2019, 06:20:47 PM by FickleLife »

Online unilec5544

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Re: Overheating 66
« Reply #8 on: November 11, 2019, 07:14:47 PM »
I have never been a "fan" of flex fans and you fan blades are to deep into the shroud.

Online sms777

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Re: Overheating 66
« Reply #9 on: November 11, 2019, 08:38:36 PM »
Like Neil(unilec5544) said reduce the fan spacer and pull the fan back from the radiator so the blades about half way protruding from the shroud. It will make a hell of difference by not scavenging the air before the shroud.
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Offline barnett468

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Re: Overheating 66
« Reply #10 on: November 12, 2019, 01:48:44 AM »
Also, how much gap is there between the outside if the fan and the shroud. I can't tell in the photo. Ideally it should be less than around 25mm or slightly less.

In general, a thermo fan will not work better than a fixed blade fan if the fans are similar in all other aspects because clutch fans never completely lock up and therefore eill never turn the some soeed/ rpm as the pump is.

All this being said, once again, it should have a high flow pump, and if your condition persists after changing the fan depth and making sure it has a small enough gap between the shroud, I would try setting the idke timing to the optimum level. I would also put a good pump on it.
« Last Edit: November 12, 2019, 01:52:33 AM by barnett468 »

Offline FickleLife

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Re: Overheating 66
« Reply #11 on: November 12, 2019, 06:29:36 AM »
Here are some more pics of gaps around the shroud and fan .
https://imgur.com/gallery/YIfJZDb

Fan to inside lip of shroud 23mm (too deep)
Gap around shroud preventing flush fit to rad 7mm
Clearance around fan to edges of shroud 20mm


Plan of attack

Water pump swap first. Options:

GMB High Performance Water Pumps 125-1420P
https://www.summitracing.com/parts/gmb-125-1420p/
About $145 landed. Best reviewed pump on summit.


FlowKooler High Performance Water Pump 260 289 Ford Hi Po
https://www.custommustangs.com.au/flowkooler-high-performance-water-pump-260-289-351~398273
$195 and I can go get it today and support Aussie business

Which on le is the better unit? Or should I get something else?

And Iíll remove a spacer to bring the fan back out of the shroud slightly. If I remove a spacer there could be 3-6cm distance to the rad - isnít this too far? What about finding or cutting the existing shroud so that itís not as deep?

Beforehand I had a stock shroud on it which I reckon didnít do much. The fan was 1/2 out of that one but I canít really tell too much of a diff between that one and the deeper one on it now. Car still boils, maybe it takes a bit longer but not by much.
« Last Edit: November 12, 2019, 07:53:53 AM by FickleLife »

Offline shaunp

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Re: Overheating 66
« Reply #12 on: November 12, 2019, 08:32:37 AM »
Flow cooler for sure. they have a machined billet alloy impeller  the distance of the fan to rad doesn't matter its needs to sit in the edge of the shroud
« Last Edit: November 12, 2019, 08:34:18 AM by shaunp »

Offline barnett468

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Re: Overheating 66
« Reply #13 on: November 12, 2019, 12:22:33 PM »
A 20mm gap is xlnt.

A high flow pump is not as effective with a standard t stat, and the water pressure from pump can prevent a stock t stat from opening properly.

In general, a fan will pull the same amount of air if it is at the end of a 10 foot shroud as it will if it is at the end of a 2 inch shroud, not accounting for turbulence etc.

There is always some gap/leak between the shroud and the rad, which allows the fan to pull a little air from there, which means it is pulling a little less thru the rad, however, this amount is minor, and sealing the shroud to the rad will not fix your issue but it will help a tiny bit, but I wouldn't bother with it just yet.

Perhaps you might also try the idle timing someday.


« Last Edit: November 12, 2019, 12:33:02 PM by barnett468 »

Offline FickleLife

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Re: Overheating 66
« Reply #14 on: November 12, 2019, 03:28:56 PM »
Thanks for the comments everyone.

I have the FlowCooler and will install this in the coming days. I'll also order a high flow 180 tstat. I will also see what I can do to pull the fan to be 1/2 in 1/2 out of the shroud, but the shroud is hella deep which means the fan might not clear hoses/pulleys if 1/2 way out. Looking around at shrouds there seems to be stock (I guess less than an inch deep) which doesn't really do anything or the one I have, 3 1/2 inch hi perf one. Ideally I need one half way..... I may cut down the shroud I have.

Regarding timing, the car has just been tuned by Chev Performance in Carum Downs. He disconnected the vacuum advance and advanced it to... I think he said 35 deg from memory. This tune happened a few weeks ago and the car has been overheating in traffic for years before the tune when it had the vac advance connected and different timing (don't know what it was).






Offline barnett468

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Re: Overheating 66
« Reply #15 on: November 12, 2019, 06:07:07 PM »
a generic high flow t stat is not the same as a milodon t stat and won't work as well.

it doesn't matter who did the timing unless they know how to do it properly throughout the rpm range, which most people do not even though they say they do.

Offline shaunp

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Re: Overheating 66
« Reply #16 on: November 13, 2019, 08:56:27 AM »
If all else fails I would stick 67 big block rad in it, I don't fit anything else, even on a performance engine it will sit right on the thermostat temp. You have to open up the core support a bit. It could be that thing is bored 60 thou or something as well.
« Last Edit: November 13, 2019, 08:58:07 AM by shaunp »

Offline FickleLife

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Re: Overheating 66
« Reply #17 on: November 13, 2019, 11:25:35 AM »
Thanks everyone for the advice - really appreciate it. I've ordered the milodon, but it's going to take a little time to arrive, so this weekend I'll put the pump on and see how I go if any good weather ever arrives in Melb. Once the Milodon arrives i'll put that on.

Interesting point Shuan on the bore... maybe it is...

Offline bobbyboy

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Re: Overheating 66
« Reply #18 on: January 24, 2020, 11:18:41 AM »
HOW MUCH WOULD IT COST TO REMOVE EXISTING 16 INCH RADIATOR IN 66 302; WITH AUTO AND AIR, AND REPLACE WITH A 67 RADIATOR AND PERHAPS ELECTRIC FAN(S)?

Offline FickleLife

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Re: Overheating 66
« Reply #19 on: February 14, 2020, 03:21:47 PM »
OK, reporting back after some time....

I have the flowcooler pump and the milodon in - the car is definitely not as hot, but it is still "overheating". When I say overheating, it creeps up to 3/4 when stationary (I haven't had a day where it's really hot yet) but doesn't happen for a while longer. Also seems to cool faster when moving and the air is ramming in. I haven't noticed the temp jumping slightly when taking off after 5-10 mins of being stationary, so the coolant is moving well at idle. So an improvement, but still not there.

I moved the fan back, cut the shroud so the fan is 1/2 in/out so it's positioned for optimal cooling.

the next step is to put a pusher fan on the front. I'll put that on and turn it on via relay when I notice temp going up at idle/in traffic. I would think this would solve it once and for all, without going to a 67 radiator (which the next step if this doesn't work)
« Last Edit: February 14, 2020, 03:23:41 PM by FickleLife »

Offline shaunp

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Re: Overheating 66
« Reply #20 on: February 14, 2020, 04:16:12 PM »
What degrees does 3/4 equal?

Online sms777

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Re: Overheating 66
« Reply #21 on: February 14, 2020, 07:31:55 PM »
75c.....sorry shaunp.....I couldn't help it... :bolt:
Get a thermo gun and give us a reading at the top hose and at the bottom hose when it's at 3/4. I am sure we can sort it out for you. 
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Offline Rocket30

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Re: Overheating 66
« Reply #22 on: February 14, 2020, 08:19:20 PM »
I've had the same problem with my 428, gauge reads hot while the mechanical reads 180f (82c)

Online USA066

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Re: Overheating 66
« Reply #23 on: February 14, 2020, 11:56:18 PM »
The link provides some good tips on cooling:

https://www.stewartcomponents.com/index.php?route=information/information&information_id=11

Our friend had a baffle installed in the top tank of his 16Ē radiator to increase the turbulence across the core, hence, improving cooling.

The gauge in my 66 reads 3/4 when the actual coolant temp at the inlet is about 180 degrees. Diabolically unreliable.

Is coolant being expelled out the overflow?
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Offline SXTY8

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Re: Overheating 66
« Reply #24 on: February 15, 2020, 10:06:29 AM »
I've always been a fan of thermos (sorry about that) as they start working when you need them most (stationary). I solved my overheating problem with a pair of Spal fans which were bloody expensive but sure can move some air.



 

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