Need help with my cooling system. (runs a bit hot)

The car is a 306 gt40x combo with trick flow cam and 600cfm edelbrock carb.


So stop and go 25mph traffic putting along sitting at a light and this thing is pegged on the gauge at 180. Even while cruising its at 180 degrees. I think maybe the classic instruments temp sensor reads a bit high. But it does boil over if you let it idle for awhile. I can let it idle for a really long time and it is rock solid at 180. But stop and go/cruise and stop, it creeps up when you stop to around 200 and spits coolant.

I have a 100$ electric fan from O'Reileys it moves quite a bit of air and is powered by a nice thermostat relay thing. It does not have a shroud but covers about 75% of the radiator on its own.

The water pump is a Proform Electric Pump.

Thermostat is a 160 degree stant brand I think.

Timing is set to like 10 degrees IIRC I set it awhile ago.

Motor is pretty much new has only 200 miles on it.


The radiator is a silla 2 row all aluminum with trans cooler provisions that are not used.




I think I need to get a bigger radiator but am not sure.


What do you recommend?

 

How big is the radiator? Sounds like it should be working fine, since it is new and aluminum. Mine is 19x22 and keeps me pretty cool in Houston heat. But, my fan has a shroud, and covers nearly the entire finned area.

I have also had decent luck with maybe a 5 -10 degree drop in temps when using less antifreeze and one of those water-wetter products. Use maybe 20-25% antifreeze, the water-wetter, and top off with water.

 

I honestly believe a aluminum rad and a Taurus fan is a must on any vehicle.. With that my on my car.. Sometimes it don't get hot enough when I leave the fan on low some times..last year my car was in 145 degree heat on the blacktop and the Taurus fan on low, with water in the rad my car ran @ 185 degrees idling in there for 15mins or so. I think maybe your issue is the fan having no shroud.. Put a shroud and see or junkyard swap with it.. Ull be more then happy, my fan was 30 bucks from a JY.

 

yep.. that's a pretty typical result for that design when the car isn't moving through air.

implement some water wetter and either dual fans to pull air through larger area of the rad(I usually offset them hig/low to cover all the cores).. or water wetter and a shroud on the one you already have.

 

Okay, I may try making a quick sheet metal shroud to help the cooling at low speed. Also maybe have "flaps" so when the car gets up to speed they can open and let all the air flow through. Kinda like the ole vw siroccos.

 

Or can I be lazy and just buy a shroud/electric fan combo?

I would not mind if the temps got in the 180-200 range but with it pissing coolant out of the 13lbs cap it is a problem.

 

a $10 bottle of water wetter may work better than you think it will.. and I'd start there first. easiest/cheapest to more time consuming/expensive is usually best. It might be more livable and quit puking in all but the worst heat.

FYI.. depending on which product you choose.. it's more effective to run lessor concentrations of antifreeze mixed with these solutions.. so full rad drains can help even more. Even with a full rad drain.. you'll still likely end up with about 30% antifreeze ratio due to all that remains in the block.

 

I actually am going to try pulling the guts from the thermostat so it is just a restrictor plate, and see what happens. I have a feeling something is funky in my cooling system, or my timing mark was off and I am running too much/little timing.

The fan moves quite a bit of air and the waterpump flows good.
Im going to try that and see with no tstat what my temps are, then if it is still too high I know it might not be a "flow" issue.

Then I could try a makeshift shroud.

I am really not running the car hard enough for it to be seeing 200 degree temps at idle with the decent rad. electric fan and waterpump. It was 50 degrees outside when I was testing it.

 

That fan looks quite small to me -- I wouldn't expect it to cool very well.

Rather than building a shroud, you'd be much better off with a Taurus fan/shroud. I paid $30 for mine. And, as someone suggested, rig up some kind of overflow bottle.

My fan was connected to unswitched power so as the coolant builds heat when the engine is turned off (that's normal) the fan would cycle a few times to dump that extra heat. The coolant circulates by convection when the engine isn't running.

An overflow bottle was installed to avoid dumping coolant on the drag strip but the bottle never got a drop.

 

Mine would run cool at first, and heat up when I idled at a red light. But it would also slowly heat up to around 220 while driving at highway speeds, so every 30 minutes or so, I had to pull over and let the car cool down. Made for long trips.

Aluminum radiator fixed most of that, taurus fan on a thermostat switch fixed the rest. Then I ran 180-185, with the occasional 190-195 in the heat of the summer. But last year, I added that water wetter and now sticks at 185 or 180. Even in August in Houston.

 

I think the 13lb cap is the reason the car is spitting out the coolant @ 200. I have my fan set to come in @200 w/ a 17lb cap and I never spit unless I have to much in the sys to start with. I run 16" @ 2700cfm aftermarket fan.

 

I am going to get a 17lbs cap tomorrow.

The removal of the thermostat "guts" helped quite a bit. It does creep up to about 200-210 and spit a few dribbles, but if let idling it will cool itself back down in a minute or so back down to 180. Seems to want to hold 180 if it just sits idling with the fan on.


I also agree my fan is DEFINITELY not up to the task of keeping this thing cool in around town driving if I jam a couple gears and stop.

I am looking for a easy fan solution, the Taurus fan is going to be hard for me to get as I have 0 free time during normal business hours.

 

Is the following statement true?

"At sea level with a 50/50 antifreeze mix a 13 psi will allow the system to boil at 260F. A 16 psi cap system will boil at 266F. Your car isn't going to be running at anything close to either of those temperatures. With no radiator pressure, coolant will boil at 224F which is too close to what the engine might see which is why radiator caps pressurize the system"

So why does my temp sensor read 180-200 degrees, it is a classic instruments sensor and gauge. It is mounted in the intake manifold. If my coolant is really only at 200 degrees it should not be spitting out of the 13psi rad cap, correct?

 

The temp sensor only measures coolant temperature at the sensor itself. Coolant temperature varies significantly in different locations in the cooling system, so above the combustion chamber in the head you could easily exceed the boiling point when coolant flow slows during low idle after a hard run or after shutdown when it stops altogether, hence the "burp".