Overheating, suggestions?

PeteB

GT40s Supporter
Temp is fine while moving but quickly goes up while still. The fans are working. This is with A/C on. It was 220F when I pulled into the driveway.

I guess I should also ask, how hot is too hot for an LS3?
 
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At what temp do the fans turn on? In my old Viper they didn't turn on until 220, so it would regularly get up in that range. 220, with ac on and hot ambient temp, really isn't bad if it can hold there. At that temp you are around 5psi in the system, as you are roughly 9 degrees higher than the boiling temp. What psi is your cap? I have run up to 25psi caps before on cars that like to run a little hot, just need to make sure the cooling system can handle the higher psi.
240-250 with a 16psi cap and you may start puking a touch, but should recover it with a tank. Water wetter works, but you will actually read higher temps due to it pulling more heat out of the motor.
 

PeteB

GT40s Supporter
16psi cap.

I let it idle for a while in the driveway with the A/C off. It just keeps climbing, unless I turn the heater on. It levels off at 221F with the heat on high, but turn the heat off and it keeps going up. Turned it off at 230F. Oil temp is pretty steady at 220F.
 

Howard Jones

Supporter
It's going to cook to death without airflow through the radiator. The SLC radiator should be able to bring the temp down to the thermostat setting if the fans flow enough air. Run the fans. If that doesn't work then there may be air in the system.
 

PeteB

GT40s Supporter
Fans turn on at 207. Ambient temp is about 85. No shroud. I don't know what temp thermostat GM puts in the crate LS3.
 
Grab a 170 thermo, Turn one fan on at 190, other at 210, and build a shroud. Should help quite abit. If you just have one large fan, turn on at 195 or so.
I also have drilled a couple 1/4" holes in thermostats before to help system burping and it really helps keep things cool while moving, but, does almost nothing if you are already going past 220 and climbing at a stand still.
 
Possibly air in the system.

But, IMO, a good fan shroud is necessary. If you are building one, please don't make a pancake-style shroud with very little rad-shroud clearance- a correctly-designed shroud makes use of all the radiator, not just the area in front of the fans. That means the shroud has to have some depth all over. Check out a few OEM shrouds for visuals.
 
Yep - ditch the "factory" fans. Here's a thread from another "coolant overheating" post thread:

A set of upgraded Maradyne fans Model TA11A3001 - solved my idling/traffic high temp. run-a-way issue.

The do draw a lot of current so I had to direct wire to battery with a fuse and a relay with no issues since.

My temp gauge at a long traffic light would hit 220* - a throttle induced fast idle would help bring it down some but it was looking like a runaway train while I hoped the light would go green. Under speed never an issue even when the air temps were in upper 90's- summer heat. It's the low idle/slow movement of coolant in summer heat that was the problem.
BTW: Both fans come on at the same time - even with the A/C, which IIRC may only trigger one fan?? How the memory fades.... I have not had an issue since and do not use a shroud. 207 degree F is the GM ECM fan trigger temp. from the lit that came with my engine controller kit..
 

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BTW: Both fans come on at the same time - even with the A/C, which IIRC may only trigger one fan?? How the memory fades.... I have not had an issue since and do not use a shroud. 207 degree F is the GM ECM fan trigger temp. from the lit that came with my engine controller kit..
Mike, I think your car is wired the way a lot of Allan's cars are, which is that if either the AC request or the ECM request for fan is on, both fans are powered.

This is easy to do- you just tie both fans to both outputs, so if either one is on, both are powered.

Mine is that way, too.
 
Will, you are correct. I tried the wiring both ways when replacing my fans and finally decided that both fans on, worked better when the A/C condenser was adding a lot of heat to my already too hot radiator - it was a better solution. I found that one fan running was not cutting the mustard.
 

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the cheapy pro-comp fans that come with the kit are more than adequate for cooling with a properly built shroud. Make sure all the air is bled out.

Also, don't forget there's a temperature difference between taking a coolant reading on the driver-side head (where the GMPP ecu plugs into) and the passenger side head (where most put their coolant sensor for dash). I think the difference is about 10* - my dash reads 195* when the fans turn on, which is about 203-207* on the driver side head.
 
Well, here you go, yes get the cheapy fans, spend hours building shrouds on a 100,000.00 car being cheap, verses spending the money on fans, not some fancy radiator, it just depends on how much you value your time, me personally, I spent almost 600.00 for everything, radiator, 2 fans, relays and don't have a problem, not even close with one of the hottest running engines ever made a rotary.


Just my work ethic.
 

PeteB

GT40s Supporter
Alex - My temp sensor is in the water pump. The GM controller supposedly turns on the fans at 207F. My temp gauge reads 202F when the fans come on.

Garry - I'm with you. I've looked at the shrouds people have made and thought I could make one, but I think I'd rather just buy fans that work.
 
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