LS cooling question..

[yukio]

Hi guys.

A question regarding cooling of LS engines.
My current setup is a LS6, with a CR racing radiator and dual 11" SPAL fans, 160F thermostat and a LS3 water pump. More than enough cooling for my setup.

However i am having cooling issues when standing still. The hot side of the radiator is hot, and the cold side is more than cool enough. This makes me belive that my fans and radiator is good enough. Without a thermostat in, it runs too cold 150ish. Which leads me to a faulty thermostat but this i my third one...

I have attached a great photoshopped picture of my setup with cold/hot arrows. My consern is that the radiator is delivering cold water to the thermostat and therefore the thermostat will stay closed, even if the engine water temp is increasing.

Any suggestions?

https://lh3.googleusercontent.com/nxAr6V8fr5P8nKyue1pcYm9c-yf3lY3alXUPdbUWyGz9AygyQWJPMgITjN6hEduzKmYSndW-T0Ruw7XmHxn0lc1yOudVf7nRdcAlAv7KK9H4MoTrt4kT2D3fdG snXQv2ujY5nPL6dZ6k58HkBY4ZLXi65U-vqTogd5_9kcgnNzDohthFTm5FP97bbF_9br1zNn06RJrEfbCYB 5JONlFNuWUkWxmJOuZQ2E74KeIFrjefcUEebAIOnRkP5I-Arh_J7nI5FZZsHzsD-0B2XZ1LoYz2SI27RilAHIU86MIqmq1KWuPUExoZa2Ki6CWI5ZH q8ltkpVDNbEs_ncnTAEDWBT3lGolE7hgC0MT1rAaJ95fJFOSeg 31d4uLvuEUqw14_SDXn5499fFF2XyrC4RNhgApvf8JVbN0Kipm uLAnzzd0U7KwQzJHFrP9eY8QhkjBxWFcy555SiubMs2z5NElWD WxPj-DINXOsOwTn1LvyixQ8Nao_dpp4qQxQ_iJcTCC7leBSGBii13eF pXt6Ito64xQzU6jaDH_REoPTAk5vF5ISgs4P18cpZ62qOELmUa k5p-wi6mcr34c7vaI3W2OkzfAOkVqnWN4Crcq2AozFjqw5O2iwNOxk DweXa95h7sdJ-T_9wGnlRtXznAZmZTEkXbbOy3dKeGplQtZCQR91_8U=w672-h895-no

[dhutton]

Isn't the temperature sensing element of the thermostat on the hot side of your pic?

Don

[samckitt]

The part of the thermostat that reacts to the temperature is on the back side of the "valve" away from the cooler fluid. The engine side is hotter & opens up to allow cool fluid through, it closes if temperature drops, recirculating warmer fluid from the engine back through it. I would say you have a bad thermostat, but you say you are on the 3rd or 4th one. So i'm confused too.

[dhutton]

The part of the thermostat that reacts to the temperature is on the back side of the "valve" away from the cooler fluid. The engine side is hotter & opens up to allow cool fluid through, it closes if temperature drops, recirculating warmer fluid from the engine back through it. I would say you have a bad thermostat, but you say you are on the 3rd or 4th one. So i'm confused too.

Is it possible to install an LS thermostat backwards?

Don

[samckitt]

No, the metal coil that controls the valve wont fit under the housing if backwards.

[yukio]

Ok, thanks for the replys.
Ill try some other stuff tomorrow.

I am still thinking that when the thermostat opens, cold water get to the "temp sensing" side of the thermostat, which in turns closes the thermostat.

Does the backside of the thermostat (passage to the heater) need alot of circulation of hot water to get the thermostat working properly?

[Chad-1stGen]

Ok, thanks for the replys.
Ill try some other stuff tomorrow.

I am still thinking that when the thermostat opens, cold water get to the "temp sensing" side of the thermostat, which in turns closes the thermostat.

Does the backside of the thermostat (passage to the heater) need alot of circulation of hot water to get the thermostat working properly?

I don't think this is it. The thermostat is more efficient if you have your heater hoses flowing full time as opposed to a shutoff valve in them. This is how all LS motors work from the factory. However, plenty of people run the ports blocked without any trouble.

I suspect air in the system. Where does the steam vent line go? Next time the car is fully warmed up and you are sitting still try reving it up above 2,500 rpm for 30+ seconds. If the temp drops then you have air trapped in the system.

[71RS/SS396]

How are the fans controlled? What's the temp when you're standing still? Why a 160* thermostat?

[dhutton]

Where did you connect the steam vent?

Don

[dhutton]

I am still thinking that when the thermostat opens, cold water get to the "temp sensing" side of the thermostat, which in turns closes the thermostat.



If this was the case every LS out there would have this problem. They don't...

Don

[randy]

fans wired backwards so its pushing instead of pulling?
Air in the system would be my guess if the fans are operating the correct way.

[Z06vette]

What temp is the car running at when standing still? What are your fan on/off temps set at? I find that air gets trapped in these setups often when firt installing everything or when the system has been drained. If one hose is cold, its not circulating,obviously. Doubt 3 thermostats are bad. Do you recall how much coolant you poured in? If the motor was bone dry initially, it will take 2.5-3 gallons to fill. To help purge the system, I found that driving the car to get it up to temp- maybe a couple miles. Then park it overnight, removing the cap after it cools. Most times, the next morning I can add anywhere from 1/2 to 3/4 gal of coolant. Keep us posted

[yukio]

Fans are controlled by ECU and they are pulling the right way. If i dont remeber correctly they are set to start at 185 and turn off at 180.
The 160 thermostat was just an attempt to get it to open earlier and therefore run cooler. I have a 180 thermostat laying around, wich i will use if i get it to run normal.
When the temp is passing 210 i am stopping the engine. With a 160 or even a 180 thermostat it should be running cooler than that?
Steam vent is connect to the cross between the heads.

I have been running the car for a week or so now. Running several rpm pulls and several heat cycles, so it find it strange that air in the system is giving me these problems. I have topped the radiator several times, and now it cooolant level does not decrease anymore. I have probably about 3 gal in it.

The wierd part is that the cold side of the thermostat is "ice cold".
The thermostat is definitely not opening as it should, and when touching the radiator only 10% of it is actually hot.

I might be trying one of my other thermostat an see what that gives me.

[yukio]

I am not cencerned about the temperature right now, since it is cold. But it annoys me that i can not make it run at the temp i want it to.
When it gets 115 outside, i think i will have a problem with a thermostat that is not opening...

[dhutton]

Where is the other end of the steam vent hose connected?

Pretty sure you have air trapped in your system. Have you removed the cap and burped the system by squeezing the hoses etc while the car is running and hot? Other trick is to raise the front of the car while it is hot and running.

Get one of those low cost IR temperature meters to measure the temperature of your coolant system. One like this:

http://www.ebay.com/itm/Non-Contact-IR-Laser-Temperature-Gun-Infrared-Digital-Thermometer-Sight-Handheld-/400664001576?hash=item5d496f7c28:g:nDQAAOSw241Ya7C 0

Don

[71RS/SS396]

Fans are controlled by ECU and they are pulling the right way. If i dont remeber correctly they are set to start at 185 and turn off at 180.
The 160 thermostat was just an attempt to get it to open earlier and therefore run cooler. I have a 180 thermostat laying around, wich i will use if i get it to run normal.
When the temp is passing 210 i am stopping the engine. With a 160 or even a 180 thermostat it should be running cooler than that?
Steam vent is connect to the cross between the heads.

I have been running the car for a week or so now. Running several rpm pulls and several heat cycles, so it find it strange that air in the system is giving me these problems. I have topped the radiator several times, and now it cooolant level does not decrease anymore. I have probably about 3 gal in it.

The wierd part is that the cold side of the thermostat is "ice cold".
The thermostat is definitely not opening as it should, and when touching the radiator only 10% of it is actually hot.

I might be trying one of my other thermostat an see what that gives me.
210 is not too hot for these engines, GM runs them that warm. These aren't gen 1 small blocks. Running them too cool has no benefit whatsoever, you want to keep the engine relatively warm so your oil temps will get up to at least 212* to burn off the moisture in it under normal driving conditions. Running your steam line low like that and then back up is asking to trap air.

[MrElectric03]

Looking at your steam vent tube it looks pretty wonky. It's probably got a loop on the motor side and looks like it runs down along the lower radiator hose then up to the port under the upper. I would start by running it straight forward from the vent and along the bottom of the intake tube then along the upper so it can properly vent. That vent can really cause some grief. Also with the angle of the filler cap you may try jacking the front the the car when you fill it just to be sure you are getting all the air out.

I also agree 210 is normal temp. All of my LS motors run around 210*

[randy]

Don't be afraid. I was afraid when my car went up to 210 but eventually thr thermostat opened up. Just the frnot of the csr up only and bleed the system. This would allow the radiator to be higher Where do you live? Squeeze the radiator hoses to to help blurp the system