Overheating 390

[simo]

 Hi Guys,
I have a '69 Mach 1 S code that runs near boiling just on a warm day. It supposedly has the correct big block radiator, also a Flowcooler high flow pump as well as a matching thermostat. At the moment I am using twin thermo fans ( pull type ) off a BA/BF Falcon and maybe these are the problem. A mate owns a Jensen Interceptor with a 440 Hemi and Falcon thermo's and they work just fine for that.
Does any one have a solution thats worked on keeping a big block at a reasonable temperature?

[jiffy]

ok - what temp is it ACTUALLY running? Have you verified it with a infrared heat gun?
what oversize is the block on - +0.060 can run hot.
What is your timing set to?
Have you run the car with an origina fan setup?

[AussiePhil]

Hey, as well as jiffy said, I've heard some high flow pumps flow too fast, not allowing the water to stay in the radiator long enough. Some may say bullS##t.
May be worth consideration!
Cheers Phil.

[69candy]

Are you running a separate gauge? I do on my 428, dont trust the one in the dash. It says half when its up to 220deg!!!! Mine runs anywhere between 180 and 220. 220 is a stinking hot day idling around town and I will turn it off when it gets to that. normal is around 190deg 

[GEOFF289]

I agree with the guys recommending getting an accurate handle on the temp and not relying on the vague dash gauge.

These gizmos are also a good thing, tells you the block temp rather than coolant temp and gives you a much earlier warning that its getting too hot.

http://enginewatchdog.com/

[simo]

Thanks Geoff, just got your message then, and yes , I'll be going out and getting a temp gun very shortly.

[pgold]

I had my radiator 24" BB for 351C at radiator shop to make shore it was clean ( and it was ) and the shop guy said we get these all the time. He grabbed a Fairlane radiator for comparison- has a lot more fins for heat transfer and it was taller. I changed thermostat, checked spring in bottom hose, checked timing, installed BA falcon fans. It was now good around town and on short runs but longer runs on highway would still over heat. I then installed a FlowCooler water pump and Maxcore radiator - 2 core 24" 390/428. Each core is 1.25" and radiator is thicker than factory so may be tight fit. I had to trim down fan shroud to clear AC and water pump pulley. Top and bottom tanks are shaped like factory and will fit 69 mounts. Got mine from Custom Mustangs in Melbourne  https://www.custommustangs.com.au/1968-1969-mustang-maxcore-radiator.That was 2 years ago. Two weekends ago was the first time I've seen temp gauge above 84 deg C it got up to 90 deg C but it was 42 deg C outside.

[simo]

Thanks for the info Paul, that confirms that i'm on the right track. I'll contact Custom Mustangs about the Maxcore radiator only I won't have enough room for the BA fans so might trade them for a 16" pusher fan & with a bit of luck that might do the job.
Cheers, Greg

[AussiePhil]

Hey Greg,
If you have to fit a fan there's only one brand to buy, SPAL.
Try to get a low profile pull fan as big as you can get!
Cheers Phil.

[pgold]

If you have not already have a read of old post. https://www.mustang.org.au/forum/index.php/topic,34932.msg330865.html#msg330865
With a efficient radiator and you don't have AC your old shroud and mechanical fan may be all you need ?

[barnett468]

what oversize is the block on - +0.060 can run hot.

You need to answer this question if you know what the bore size is.

If it is an old engine, it is possible that some of the water passages are restricted from rust build up.

If it does NOT have high compression, ie around 170 psi, and it is not bored to .060" over, and it does not have ac, then it will be easily fixable, but the timing must be set to the optimum level first as incorrect timing on a big block can contribute a fair amount to running hot.

Also, not all radiators are created equal, if it is bored over .040, then you may need to use a high efficiency rad which is quite expensive. Factory falcon fans should flow enough air.

You should run a brass milodon t stat with a high flow pump because the higher water pressure created by the high flow pump can affect the t stat function causing it to not work as well as it should.

Does it run hot while driving or at idle?


COOLANT MIX

If you use 70% de-mineralized water and 30% old school prestone green coolant, and 1.5 times the recommended amount of DEI radiator relief additive, it will run cooler than the standard 50/50 mix, guaranteed.
.

[barnett468]

Hey, as well as jiffy said, I've heard some high flow pumps flow too fast, not allowing the water to stay in the radiator long enough.

Absolute nonsense, because the flow/temp is controlled by the t stat, NOT the water pump. .

[barnett468]

I had my radiator 24" BB for 351C at radiator shop to make shore it was clean ( and it was ) and the shop guy said we get these all the time. He grabbed a Fairlane radiator for comparison- has a lot more fins for heat transfer and it was taller. I changed thermostat, checked spring in bottom hose, checked timing, installed BA falcon fans. It was now good around town and on short runs but longer runs on highway would still over heat. I then installed a FlowCooler water pump and Maxcore radiator - 2 core 24" 390/428. Each core is 1.25" and radiator is thicker than factory so may be tight fit. I had to trim down fan shroud to clear AC and water pump pulley. Top and bottom tanks are shaped like factory and will fit 69 mounts. Got mine from Custom Mustangs in Melbourne  https://www.custommustangs.com.au/1968-1969-mustang-maxcore-radiator.That was 2 years ago. Two weekends ago was the first time I've seen temp gauge above 84 deg C it got up to 90 deg C but it was 42 deg C outside.

Clevelands also tend to have problems with the factory t stat setup, and benefit from having a bypass plate installed so they can run a windsor style t stat.

[GLENN 70]

Sounds like more of an engine problem than a radiator / fan problem .  A few questions , when does it get hot ? Sitting in traffic or cruising ? ,  has the engine been bored out with over size pistons ? ,has the radiator been cleaned / And  rodded  / reconditioned ? .  The fan set up you have is very good but when do they come on ? . In the past I have taken out one welsh plug ,the easiest one to get to then flushed the block and have seen so much rusty muddy crap come out even tho it had a radiator flush .

[barnett468]

In the past I have taken out one welsh plug ,the easiest one to get to then flushed the block and have seen so much rusty muddy crap come out even tho it had a radiator flush .

Yup, rad flushes are nearly useless. On old rusty engines, I run straight water and oxalic acid in them for 2 or 3 days, and this eats the rust.

[simo]

 THANKS Guys,
The motor was rebuilt by the previous owner in the States and never run. I have not had the heads off so don't know what it's been taken out to but had the sump off and it's been bored and new pistons fitted so must be over sized. It looked like the block had been hot dipped as it was spotless so would think the water galleries would be pretty clean.
 The radiator is brand new 3 core brass & copper unit and was sold to me as a big block radiator and the thermo is a hi flow to match the Flowcooler pump.
 On a hot day it will cruise on at least 90C as the fans are set at that and they are running but on stopping and idling it will hit boiling.

[AussiePhil]

Hey Simon,
A lot of people sell high flow fans, but when you put them next to real good brand fans you can see the difference.
But even if you had poor flowing fans it shouldn't boil.
Something else is wrong.
Do you have a automatic transmission cooler in front of the radiator? If you do and you're pushing air that could be a problem.
I had trouble with a huge intercooler heat exchanger in front of the radiator, needed to change it for two smaller ones.
Cheers Phil.

[simo]

Hey Phil,
 Yes, I do have an external trans oil cooler in front of the radiator and I was wondering if it would make a difference, so i'll be changing that over to the standard cooler lines into the radiator fittings ASAP. Have already removed the air con condenser as it's not set up yet ( and may not be ) so with the oil cooler gone it should give it better air flow. Might also look at a Spall fan as well.
Cheers, Simo

[AussiePhil]

Hey Simon,
Sounds like you're on top of it now!
Cheers Phil.

[barnett468]

The radiator is brand new 3 core brass & copper unit and was sold to me as a big block radiator...

Unfortunately this means nothing because you must find out what size the tubes are. The chinese rads use smaller tubes than the factory rad, so if it has small tubes and the same number of tubes as a stock rad, it holds LESS WATER.

...and the thermo is a hi flow to match the Flowcooler pump.

This means absolutely nothing. I would start by removing the t stat and determining exactly what it is. . You should run a brass milodon 180 or 190 or 192 t stat.

On a hot day it will cruise on at least 90C as the fans are set at that and they are running but on stopping and idling it will hit boiling.

Ok, ideally the fans should NOT be running on hi full time when the car is going around 40 mph or more. If they are, you likely need a bigger rad. If they are not, it sounds like it is mainly an air flow problem, however, a spal fan will not flow more than a factory electric fan, and if the factory electric fans do not keep it at 90c at idle, you definitely have too small of a rad if your t stat is a brass one that is 180 to 192 degrees.

Also, if the external oil cooler is only blocking 1/3rd of the rad, then removing it will do very little and definitely will not cure your problem. Also, the oil cooler should not be touching the rad. There should be around 1/2" to 1" of clearance between it and the rad.

[AussiePhil]

Thanks for the info Paul, that confirms that i'm on the right track. I'll contact Custom Mustangs about the Maxcore radiator only I won't have enough room for the BA fans so might trade them for a 16" pusher fan & with a bit of luck that might do the job.
Cheers, Greg

Hey Greg,
After reading this I got hang up on that you were now using a push fan.
So yes, the additional cooler in front won't make much difference, as Barney said.
I really don't like push fans! Especially if you've got layers off heat exchangers, (radiator, cooler, evaporator)
Like Barney says about the tube size drain some of the coolant and try to measure the length of the tube through the radiator cap hole, and research this against stock big block radiator.
The thinking now is less rows (2) but longer tubes getter better heat transfer! IMO!!!
Pull everything apart so you know what you've got, especially the thermostat!
BA fans are good but bulky, I've got a great original fan but three times as thick as my Spal and Davies Craig fans.
My fans are offset to fit, I've got an 8" supercharger pulley three inches from the radiator.
One big fan is good but you may have to use two to suit the water pump pulley.
Set your thermo controller as per their recommendations. I've got a Davies Craig!
If your radiator is to small and inefficient and your fans don't draw cooling air correctly and the thermostat does not control the temperature correctly a high flow water pump IMO will flow the coolant to fast and make things worse!

All the best, hope you start getting results soon!
Cheers Phil.

[pgold]

The thinking now is less rows (2) but longer tubes getter better heat transfer! IMO!!!
GO to the link and educate your self.https://www.custommustangs.com.au/1968-1969-mustang-maxcore-radiator-v8-289-302-351

[barnett468]

stock rad has 1/2" x 1/8" tubes on 1/2" center.

A simply way to tell tube size is measure the thickness of the core. if it has 3 rows of 1/2" tubes, it will be 2" thick because there is 1/4" spacing fore and aft (front to rear) on the tubes.

[barnett468]

The thinking now is less rows (2) but longer tubes getter better heat transfer! IMO!!!
GO to the link and educate your self.https://www.custommustangs.com.au/1968-1969-mustang-maxcore-radiator-v8-289-302-351

It is not as good as a multi pass or horizontal tube rad, but they fail to tell people that, but it is a nice rad for what it is, but it would be next to impossible to run a stock fan and fan clutch on it.

[pgold]

stock rad has 1/2" x 1/8" tubes on 1/2" center.

A simply way to tell tube size is measure the thickness of the core. if it has 3 rows of 1/2" tubes, it will be 2" thick because there is 1/4" spacing fore and aft (front to rear) on the tubes.