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It's summer and I'm experiencing the "big block" overheating problem. I've got a high flow water pump, 180 degree thermostat, replaced the stock rows in the radiator with a 4 row Modine (in my original radiator), the clutch fan is working. At 75 degrees ambient the car runs great but anything over 85-90 and it'll heat up. The gauge is pegged at idle and the car has a hard time cooling down even when I'm running down the road. (It puked on the garage floor yesterday.) I put an infrared heat gun on it and it's running 207-213. (190 on the bottom hose). Thinking of putting a pusher fan in front of the radiator. Not thrilled about it because the car is restored back to original, but I'd rather not ruin anything because of the heat. Does anyone have a suggestion as to what fan I should get?
while 213 isnt really that bad I can see your concern being that it sounds like its occurring around 90F outside air temp. It typically takes traffic, dead stop and 110f to get mine up that hot. I usually run 193 on the freeway and 208 stopped when its over 102 outside.
What does it do when you are on the freeway?
When did it last run right? When did this start occurring?
I believe it's just over 200 running down the road. I'm really leaning toward the pusher fan even though it will look funky under the hood. The car is show winner and I've done my best to keep it stock. I don't want a trailer queen but I also don't want to overheat going to or coming from a show. It's embarrassing to puke green stuff.
You only have a 10 to 13 deg difference between 70mph of ram air vs stopped with the fan doing all the work.
In my case its a 15deg difference but ambient air temp does play a roll If I recall correct at 80f there is little to no difference and at 35f to 40f the engine actually runs below the Tstat temp because of the bypass hose alone and the near freezing water temps push engine temps well below what I would like and I often get frost on the carb body.
The typical issue for a bad fan system is you might see 195 on the freeway but engine temps will move up as the car sits and will climb past 220 no problem within a 2 min period. This indicates a good cooling system that is getting inadequate air flow at a stop. A 25deg and climbing difference that occurs pretty quickly
If you are running hot on the freeway that would indicate a bad radiator or issues with the cooling jackets.
Are you pretty sure the IR temps are accurate? IR temp guns dont like shiny surfaces make sure you are measuring something flat in sheen like the rubber hose.
It seems to me that it would take more than 213 to get to puke water..
Have you considered something more simple like water wetter, it states it can reduce temps up to 20deg F.
It is available from one of our sponsors here.
Also have you had the rad cap tested to verify for proper pressure.
Last edited by AK_Kayaker; 07-29-2017 at 05:07 PM.
The car has run hot since day one. It hasn't puked for quite awhile but we haven't had temps this hot for awhile. You're right about the shiny service too. The bottom radiator hose was a good indicator. It was reading 195 there and above 200 on the top hose so things are working as far as some cooling. Thanks for your input Gun Jam I appreciate it. If you'd like to see a pic of the car send me your email and I'd be happy to send a couple.
Thanks again.
As far as the water wetter goes it only works with water and is not as effective with anti freeze. It gets too cold here to run just water and freezing up is a real possibility.
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So did a quick comparison test on my 302 with electric fan and high efficiency U.S radiator Aluminum x flow.
I think the T stat is 185
ambient air was 102 (ir gun)
water temp was 184 from behind the Tstat measured with onboard Arber instruments sly-1612 accurate with in +- 0.10 degree in real time.
bottom hose was 149F (ir gun)
Fan controller was set to run near 100%....This is odd in my case because I use a PWM fan controller. it has infinite fan speed up to max RPM @ 13.8V so rather than it just coming on to 100% and shutting off it stays at a constant RPM to maintain a set temp (195) in my case....if temps creep up the fan follows as temps drop off the fan backs off very smoothly. I over rode this feature and set the fan to run about 90% power. I did this to test for max heat dissipation which forced temps below my set point (195) and caused Tstat to regulate temps.
The shaded driveway is much less abusive than a packed road. Incoming air temp was only 102. The blacktop in sunlight can run past 130 no problem out here plus the hot air being dump by surrounding car can easily increase incoming cooling air to many degrees above actual air temp in the shade. (weather station) In these types of conditions the fan usually runs flatout and still can't maintain much below 210f but in my driveway could easily dump 35degrees and keeps temps to Tstat regulation temps (185) I suspect when its running 213 the Tstat if fully open and water enter into radiator is 213f while I would guess water exit into engine is probably 200f (a 13 deg diff vs 35)
As far as the water wetter goes it only works with water and is not as effective with anti freeze. It gets too cold here to run just water and freezing up is a real possibility.
Not true. While it is true that it's a great additive for water-only systems (ie. some racing events), what it does is lower the surface tension of the coolant mix. This is particularly helpful in standard cooling systems using coolant (antifreeze) with water, as coolant has a higher surface tension than water.
I run a 60/40 water/coolant mix with a bottle of water wetter. I also use "universal" coolant designed for imports, as it has more additives in it to prevent aluminum corrosion. I'm not sure if you can run 60/40 based on how cold it is in your area, but it would be worth checking.
07-29-2017, 12:58 PM
1969 S Code Mach 1 overheating.
