...as well the radiator cap, engine doesn't over heat.Infact it seems to run at temp, right around 185/195, at 205F the fan will cycle on if the car is not moving & will not shut off (another concern) until back in motion.At which point, fan will shut off within a minute.

Question is, How normal is it for the lower rad hose &/or cap not to be hot as the rest of the system? I can put my hand on either & hardly any heat is felt.

Is the water only cycling thru the pump/stat, back into the eng?

Could the stat not be opening? Or something else, any input appreciated.

 

What controls your fans and where did you put the coolant temp sensor?

Fans cool the fluid in the radiator, not the engine. I have a feeling your fan strategy doesn't compliment what the engine needs. Could be because of where you put the temp sensor that controls fans.

 

Sensor is in the pass head.Computer controls the fan.

 

I know cooling systems pretty well after fighting issues and finally building my own setups.

As stated, fans and radiator control fluid temps in the rad, the engine produces the heat and the radiator/fans being it down(dissipate the heat), the engine and rad are 2 different temps that meet in the middle lets just say. Your Radiator inlet (upper driver side) will be the hottest part in the cooling system that you can touch. You should see a 10*F minimum temperature drop between the radiator inlet and outlets (upper and lower hose). The temp drop between the 2 is the radiators efficiency in cooling down the engine coolant temps.

Now onto your specific issues.
1.) the lower rad hose could be cool enough to touch and not burn your hand, the coolant coming out of the radiator should be much cooler than the fluid going in. Cooler fluid goes in and cools the heating motor thus increasing the fluid temp and going back to the radiator and the process repeats.

2.) If the engine is not overheating then your system is working correctly, I would verify all the air is bled from the system, air pockets can cause alot of issues along with random bits of overheating, spot boiling/vaporizing and cavitation in the waterpump.

3.) What are the specs of the radiator, fluid used (type, how old) and the cooling fans (Brand, size, CFM rating), water pump, tstat temp and brand (high flow/low flow) has the TB been bypassed or the crossover been deleted? More specs are needed.

4.) Now the sitting still and overheating. If the car is below 35-40mph the cooling fans provide ALL the air moving through the radiator thus controlling cooling. The speeds are low enough where outside air is not strong enough to overpower the fans. So anytime you have cooling issues where the temps do not drop and your below 35-40mph or sitting still your limited to 3 things (Coolant flow, Radiator size, Fan CFM). Anything over 40mph and your fans become useless and all flow through the radiator is basically all outside air being forced through the rad. Since yours is fine moving but yours overheats as it sits you have narrowed it down to 1 thing. Basically your fans are not up to the task, but you might also have a low rpm coolant flow issue as well.

5.) Coolant flow can be affected by hose quality (could be collapsing but usually under throttle and the lower hose), as well as radiator flow (old clogged cores), but the main thing is underdrive pulleys. Underdrive pulleys are such a gimmick its not even worth the meesley 5-10hp since you kill the efficiency of the water pump and alternator. If you have underdrive pulleys remove them immediately. Radiator style also affects coolant flow, most people don't know as you increase radiator core thickness you increase static pressure required by the fans to pull air through, thicker rads are less efficent than thinner rads but they make up for it in sheer surface area, as long as air movement is compensated (bigger fans or more air available). Also double pass/triple pass radiators are not the greatest as everytime you increase a pass you limit the area of the radiator. not to mention your water pump flow needs to be multiplied by some insane number to flow enough to get the efficiency of a single large pass radiator. Double/triple pass radiators are great for sprint car/oval track as those motors spend lots of time at high rpms so the pumps are flowing at the max all the time, bring a double/triple pass down to street rpms and your cooling will be much worse than a stock application.

Once you have verified your specs and the condiiton of the parts/fluids you can make a more informed guess. My guess with the information provided is your cooling fans are undersized and you need more CFM. Sorry for the rant, figure people sometimes should know why people answer the way they do.

 

1.I know how the cooling system works, but maybe the LS engines are more efficiant than a traditional sbc.Which prompted my question.I can't imagine the system cools the fluid to the point I can leave my hand on the lower rad hose for any length of time.The upper hose & heater lines are very hot during this time.

2.I have bled & rebled the system 4/5 times already w/ same results.

3.Champion rad 3 core, stock stat/pump/pulleys, 16psi cap, spal 2070 cfm fan.System was flushed as well.

4.The eng does not overheat, even when stopped.The temp stabilizes at 194-196 after the comp triggers the fan @ 203*.This was the case with the stock fan.The spal unit just lowers the temp a bit quicker & about 4* lower than stock fan, but neither will shut off until the car is in motion.

5.Everything is new, including the eng.Radiator is about 1.5 hrs old.There shouldn't that huge a difference between the up/lwr hoses.Unless the ls series eng operate that much better than the old sbc's.I may try a lower rated stat & replace the rad cap.

I should add that I have a aux spal fan wired independently of the system.I have it set slightly higher than the main fan.It has yet to activate.I also have this fan wired to run on AC by way of the Hvac control.

Thanks for all the advice.

 

No problem! Responses in the quote in bold.

 

I don't know the part # off hand.Spal fans are rated with a load , so the 2070 rating is pretty spot on.Which is considerably higher than the stock fan.Even myy aux fan is 1050 rated.

I already have a 180 stat on the way.I was gonna test the current stat out of the eng, just to check.The fan sequence I can't do anything about.It's controlled by the ecu & I'm not messing with that area.
The champion rad is as good as the BeCool unit that in there prior.I keep thinking the stat isn't opening & only circulating fluid thru the eng/heater core & what little squeezes by thru the bypass on the stat.This is why the lower hose is much cooler than should be.Only other issue is the generic cap that's been on there since before the be Cool rad was installed.Will change that too.

Hopefully this will resolve my issue, thanks again.

 

Sounds normal to me. Not sure why you want the lower hose hotter??

 

Yea they are the only ones rated at load and def some high quality fans.

Well it would be very easy to change the temps in the ECM if you had the means to do so. They are very simple changes and people on ebay etc charge like $60 for stuff like that.

You can sure test the Tstat that would help diagnose it. The champion rads are not even close to the cooling capabilities of griffin/howe/becool/northern. Champion uses 1/2" -5/8" thick cores compared to the full 1" cores used by the above companies. The less cores also allow air to pass through the rad more easily. the larger cores allow more fluid with more surface area. The champion rads 3 core is less efficient than a quality 2 core (1" rows) radiator. That's why I use the word "decent" as they are better than a stock 1 core rad but not as good as a quality 2 core rad.

good luck!

 

Not saying I want it hotter, infact if it wasn't for the fan constantly running at stand still.I wouldn't really care how cool the lower hose is.
That said, upon closer inspection, looks like my radiator cap is leaking past the first seal (nto the expansion tank).The outer seal is intact.Regardless, time for a new cap.