I have an S10, 6.0 LQ4 basically stock, has cam and twin turbo setup. The radiator is a large Summit Aluminum, 16" electric fan with shroud (on temp 180, off 170), 165* thermostat, 3400 stall convertor, transmission lines into radiator then to auxiliary cooler out front of radiator. I can sit and idle with temps ranging from 175-190, dropping with fan. If I drive the temps increase to 220+ within 10 minutes. If I'm cruising and click into neutral and let it coast, the temp will drop to 205 210 sometimes lower depending on how fast and far it coasts. I had a 187* thermostat which was much worse and thought the 165 would be the solution but unfortunately has not completely cured the issue. My only other thought is the shroud is blocking airflow or the transmission lines need to be removed from radiator. And help or suggestions will be appreciated.

 

You might have a water restriction or air pocket somewhere in the system. Make sure the return hose(water FROM the radiator) isn't sucking closed at higher engine speeds. I notice it is a swap, so the return hose could have started life being intended as a "top" hose meant to take water TO the radiator. Many return hoses have a spring inside to prevent sucking closed; yours might not have that. Something to check out...

 

It doesn't have a sprung I know that much. It is a lower hose but definitely not direct fit. It is very short and difficult to find one that works. Maybe I need to make one. Then I can be sure there is no problem. Thank you for saving some hair on my head!!

 

I know how ya feel! I don't have much to lose up there myself! It's an endangered species! lol










vvvvvvvvvv OK, quit laughing so hard! lol vvvvvvvvvv

 

 

With that setup I wouldn't run the trans fluid through the radiator, I would make the trans cooling a stand alone deal. (Use an external cooler only)

Then add some flaps to your shroud to keep the shroud from choking off flow.

Look up fan shroud flaps

 

I ordered an aluminum hinge to make some flappers. Probably do 4 good size ones around the corners.

 

Going to try everyones ideas one by one to see the improvements. Unfortunately it started hammering down rain so may not get to try anything today. Thanks again for all the ideas and look forward to sharing results.

 

If you are looping the heater core lines that may be contributing. Ideally they are blocked off completely. Some percentage of your intake water is coming directly from the loop, i.e. hot block water is being recycled right back into the block (without ever going out to a real heater core and returning cooler)

Another thing is the steam port. I did a little testing and fairly confident that tapping the upper water pump is not ideal. It should route to the upper radiator tank or some other kind of aux swirl pot device.

last make sure you are using only distilled water to diagnose cooling system issues. Do not add anything to the water until you solve all issues. 100% distilled allows you to also drain anywhere, anytime, at whim. useful for diagnostics to have that in there.

and last last, make sure there is a full compliment of ignition timing during a cruise situation. The LS seems to enjoy 38 to 45* btdc of timing in typical overdrive cruise scenarios (at 3200lbs at least). If you are using, say, 25* to cruise, it will get hot much faster.

 

I've made a new lower hose, going to drive tomorrow and see.
So first you suggest blocking the heater hoses completely or add some sort of heat exchanger to act as a heater core.
Secondly I do have the rear steam ports routed to the front ports the to the top of the water pump just above the outlet so that might be a bigger issue to change as I have no where on the radiator to connect so a bung would need to welded.
Lastly the timing may be most of the issue from your explanation. I'm running 18* throughout idle and cruise then gradually dropping to 12* around 5lbs of boost and up. I haven't begun to change the timing but will look at that as first suspect if lower hose change doesn't help. And here I was thinking "well maybe 2 or 3 good suggestions and one will cure it"! Holy smokes I may be in for a long week!!
Thank you for those suggestions

 

a heat exchanger, anywhere extra installed is handy device for moving energy around in the form the engine makes as change in temp of coolant. If I was driving up a very cold mountain and it was getting more and more cold as I drove on, I would want max temp inside my in-car heat exchanger, so that while driving I could gradually have it get back into the engine to help keep it warm enough to burn fuel properly. It works the other way as well.

If an engine is making alot of power- lets say 2000 horsepower is possible. It may be putting more energy into the cooling system in the form of temp raise than the system can dissipate the way it came originally. The temp would never stop rising, it can escalate until the engine explodes violently or melts and fails quietly. The bigger the engine, the more complex, in general, as you can imagine.

 

Well after trying to decipher this I realized something.......You didn't copy and paste some technical article that doesn't apply and you don't understand


Op I have a 6.0 with LSA supercharger on a 2000 S10 and it never gets above 200* not matter how hard I drive it and if just cruising around temp is in the 190* range with the stock thermostat. You could have a issue with the tune or it could simply be that you're not getting all the air thru the radiator.
When it comes to your thermostat you have to remember they are there to regulate minimum operating temperature not maximum. So a 165* or 185* thermostat are both going to be wide open @ 190* and have no effect on your overheating issue.
We just finished my son in-laws 6.0 4l80e swap into a 73 Nova and have the heater hose looped on the pump without issue. He's running the stock radiator with an electric fan and virtually no shroud but the fan will literally suck paper to the radiator from a couple feet away and sounds like a jet trying to take off lol.
Have you checked to be sure the fan is indeed pulling/pushing air into the radiator and not the other way around? ( it happens on occasion)

 

Fan is correct, thermostat helped as it will now stay 180 fan comes on and brings it down to 170 then fan off. My main suspicions after suggestions are lower hose and timing. If those don't correct it then I will be opening some holes in the shroud witg some flappers and so on and on through all above suggestions.

 

the example is perfect and it illustrates the reverse of how we would use a heat exchanger (like a radiator or heater core) in a hot environment. If the engine is over heating and radiator is at max capacity for heat transfer I could run the heat exchanger inside the vehicle (heater core) to cool the engine. Same way as I could warm the engine going up a cold mountain where the radiator was cooling the motor more than I stop it from doing so, once charging my in-car version. temporarily, of course, once the in-car exchanger was maxed either way it would end. It acts as a battery, a storage, for whatever temp I decide to keep in it from what is available. Additional sink/capacity.

 

Above mentioned suggestions are good. Any pictures of the rad/fan setup? Good radiator can sometimes crutch a crap fan or vise versa.

What are the dimensions of the “large summit radiator”? I know it’s not what you want to hear, but most of those summit cores don’t perform well in my experience. First step should be to run the best and biggest core you can. Largest double or triple pass HOWE radiator you can fit is the way to go.

What brand fan? What CFM? Most of the aftermarket fans are also a joke CFM wise. They also like to advertise “open” CFM flow. Once you put them in a shroud behind a radiator they flow much less than advertised. A good fan can go a LONG way. The 1996 ford Taurus fan is the go to monster for a reasonable big CFM fan. It may fix your issues alone. You can get them through Rockauto pretty cheap.

 

My favorite fan is Altima 93-97, fits my OEM size radiator fine (non-Fbody though). One fan turned on high at 187*F brings it back down to 180*F all day, non stop Florida concrete summer traffic. I have it set to bring second fan on at 189*F and it rarely trips. I am going to use A/C by next summer so I expect to need it. I also have trans cooler in front of radiator- it keeps the trans cooler below 170*F also coincidentally, for the first hour of driving, then gradually touches 175-180*F and stops. Trans cooler has a fan on it but I haven't needed to wire it up yet because of the current results.

93-97 Nissan Altima Radiator & Condenser Cooling Fan Assy
$75 shipped from ebay

 

Crapy photos but kinda can get the idea. Radiator core is 22.5x18 overall is 27x19. Fan is cheap Amazon 300CFM but works good when idling.
I set the timing around 32-36* degrees during cruising, (copied the colorado table with small adjustments), changed the lower hose and still climes to 220 when cruising after about 15 mins. So I'm thinking next I'm gonma move the trans cooler to the bad with a fan and look for a heat exchanger from an air to water intercooler setup. If that doesn't fix it then I guess it's pony up for a big boy radiator. What about bending tabs in the shroud opposed to hinging the flaps?

 

Can't see it real well but what's going on with the lower radiator hose? (edit: Is that the new hose or old setup?)
If I get a chance I'll see what the dimensions of the Ford Thunderbird fan (single) that we put on the Nova, It pulls some serious air and you can pick them up cheap and you might be able to retrofit it to your shroud.

 

It's basically just a coupler for the steel to the thermostat then again at the radiator to eliminate possibly the hise collapsing. The fan is not the issue as it works to cool it down when it's sitting. It only gets hot when I'm cruising along. Stop and the fan kicks on and temps start dropping, then back on throttle, fan kicks off at 20% throttle and once I'm back up to cruising speed, temp goes up.

 

Why have the fans shut down at 20% throttle? My truck will run hot unless the fans are on until I'm doing at least 50mph and sometimes it comes on even then. I run the Holley so I have my fans set by temp and speed. Fans are off at 50mph unless the temp is higher than 200 and then the fans will kick on at 100% If it's a hot day or if the road has many hills the fan does kick on here and there.