I am seeing 240 water temp! Think I even saw 252 at one point. The car was just idling in my driveway.
I have a LS1 in a 80 vette, dual electric focus fans from an 04' bought new, and a new stock radiator. I have see the other write ups on installing focus fans on the radiator and it works just fine.

Suggestions?

I measured the temp from the gauge in the car and from the ECU.

 

Stuck thermostat? This started with the new rad and fans? Have you removed all water from the system?
1. Top up rad fluid when cold
2. Start the car, as temp rises check the upper rad hose for temp. As the motor heats the hose will begin to get warm at the intake. as the temp rises to the value of the thermostat the rad hose should get warm at the rad side if the thermostat opens.
3. If the temp gauge reads beyond thermostat value but the termostat is still closed (rad hose cooler at the rad connection), squeeze the upper hose by gloved hand at the thermostat side with fast hard pumps. This may unstick the thermostat if thats the problem.

Good luck.

 

I will try that...

As of when it started... well, shop installed everything and did a horrible job and it was not even close to being right. I have been fixing everything they have touched for the past few months. I noticed the electric fans were able to move around a few inch's and two of the four plastic straps they used already broke. Then I found the heater hose not hooked up and shoved out of sight... and the list goes on and on and on. I limped the car home cause they told me it was complete and ready to go... blah blah blah long story I can go on about... anyways, the only change I made was added the lines for the water heater hose's to the water pump. I have no idea what the water temp was driving home cause the gauges did not work right. So I took it all out, fixed the trans cooler, fan mounts, heater hoses and re-installed. Now I am just trying to figure out if it is something simple for the heat problem or if I need to get a bigger radiator or fans. I will start simple first and try what you said. At worst... I can remove he entire thermostat and run the car without it to test the temp if the hose trick don't work.

Would you think the heater core could be causing this problem too? I had the heat on in the car when it was saying 240 but it was not blowing any hot air.

 

Oops, I think the heater core does not rely on the thermostat, now it sounds more like a water pump issue. Double check coolant level is good. Did you refill after finding the heater hose off?
Need a Guru to chime in now.

 

Are you using the right temperature sender for the gauge? I know stock c3s used a 1/2" sender and new engines run a 3/8" sender. You could have the wrong resistance in the sender causing the gauge to read high.

 

Yea. In order to install the water heater hoses everything had to come out including the pump. Pump was modified to accept them.

Engine has two ECT. One for the ECU and the other one came with the dakota digital gauges and was tapped into the water pump as well

 

What thermostat housing (CSR?) and thermostat (Gen I SBC?) did they use?
Is the radiator hot?
Is there a heater control valve?
Is the water pump turning the correct direction?
If the heater is not blowing hot and the hoses are cold, you've got a big circulation problem.

 

What thermostat housing (CSR?) and thermostat (Gen I SBC?) did they use? housing from hotrodlane.cc I had to get the straight one. Thermostat I am sure is the stock ls1 that was on the motor...
Is the radiator hot? never crossed my mind to touch
Is there a heater control valve? Yes, the original one from the old setup
Is the water pump turning the correct direction? Yes
If the heater is not blowing hot and the hoses are cold, you've got a big circulation problem - Did not check the hose for heat.

 

Basic engine knowledge man, you need to buy books or read over the net about engine operation stuff, it's not a easy topic, mucho to understand....LOTS of aspects done from 80 years of engineering and discovery today it seems obvious to us old hands, but i'ts been ingrained over decades of car hobby....

first thing is pull the stat and re do the housing without anything in there, see if you have a overheat problem then....I BET you don't....

so to buy another stat, maybe 180 or 195f but I BET the opening in the thing is the same diameter.....and if so you need drill 3 bypass holes in the in the skirt of the stat to allow water to bypass and increase the flow even when open....

now in really cold weather, that will decrease engine temps

electric fan on/off times are entirely another matter, as if effective airflow from a engine/belt driven fan, much less at 40mph + speeds....

mechanical fans can be ineffecive also....electric fan typically run or NOT, but with those vettemod situations you need to consider radiator/plumbing/shrouding/air flow,

sorry to bury you in variables....but more info and knowledge need be applied....

 

On the LS1 the thermostat is an integral part of the housing. The strait CSR housing uses a Gen I SBC thermostat. Not sure what the S&P uses, I would look it up but their website is useless. Confirm the thermostat is correct and in the correct orientation.
Dont worry about the heater unless you're absolutely certain the heater control valve is working.
Start it again, check the radiator (end tanks) and both radiator hoses for temp after it gets to 200 degrees.
You also might have air trapped in the system. Are you using the surge tank? I'll assume not since your heater hoses were not hooked up. Is the radiator cap at the highest point of the system?
Describing, diagraming, or pics of your cooling system would help.

 

I confirmed with S&P its all one piece... Wow, so when the thermostat decides to quit that will be an $80 fix and a week to get the part... I don't like that. However, I can test the stat in water on the stove to see if it opens correctly. It is a 195 he said.

Radiator cap is the highest point of the system.

S&P said air pocket as well. Told me to raise the front of the car, remove top radiator hose and pour coolant into it. Plus, some of the other things yall suggested

As for routing... stock style radiator, passenger side bottom of radiator hose to the thermostat, driver side top hose to the intake, over flow hose to coolant container under the passenger fender, One more small hose goes from one head to another and makes a T to the top of radiator.

 

What about the steam hose?

 

That is the small hose I mentioned above. The TB is not connected to it.

 

On mine the Griffin thermostat was an inch or 2 below the high point in the LS motor.
I had to add the inline thermostat over the center of the radiator since I got rid of the surge tank. Jacking up the front of the car might help too but I would double check the radiator cap as the high point.

 

I used the straight thermostat housing from Street and Performance. I used my stock sender and installed it on the waterpump.The temperature has never been above 205 on the hottest day.How about your steam tube? I had a bung put in my Dewitts radiator and ran the steam tube to it.Also I am running Spals fans and they are controlled by the ECM and the AC switch. No problems at all and this set up has been in my 73 for 6 years.Charlie

 

Jack up front of car those engines trap air in block & the steam tube must be connected
Mark