Good Evening All,

I have had my 73 LS3/TR6060 on the road a bit and so far it has been running great. When I first put it on the road I filled the coolant system with distilled water and I have ran that for the last few weeks. Now that it is getting cooler I figured I should put in some antifreeze so I drained it from the radiator and filled it with the orange stuff. The car has a new 2000 Camaro radiator with electric fans, new Corvette water pump and the top steam vent ties into the hose that goes from the water pump to the radiator. After filling it (I filled the radiator and did some jelqing (don't google that) of the upper hose to get it full etc.) I took it for a drive. Admittedly I don't know how much distilled water came out, I just drained it near the garage. I took it for a short drive and the temperature as measured by the ECU went to about 245 and the gauge in the cluster as measured at the rear of the passenger size head went into the red. I pulled over and popped the hood and it did not seem that hot, ignoring the warning on the cap I opened it a bit and it spit out a bit and then it sounded like something happened in the radiator/engine where there was some gurgling. I got in and fired it up and the temp came down a bit, then drove back to the house (this was all about 3 miles round trip) and it cooled down to normal or a bit below. So what do we think happened, it kind of seems like the thermostat did not open, was it coincident with the addition of antifreeze, or was there some air in there that did not allow the thermostat to open? After it cooled it drew almost everything out of the reservoir and then I was able to add another quart to the radiator.

Any feedback is appreciated.

Scott

 

Pure speculation on my part but it sounds like you may have had a temporary air pocket in the system in the vicinity of the temperature sensor.

DC

 

Do you have the heater hose blocked?

 

Not blocked, but I have the heater bypassed with that little loop.

 

I would agree but both the ECU sensor (not sure where that reads from) and the one in the passenger side head that I have wired to the original gauge were both very high and both came down at the same time.

 

Steam port- how high up on the on the hose do you have it placed-the higher the better.

 

Here it is, I tied in where it was the most convenient, not the highest.

 

I took it out twice yesterday, letting it cool completely in between and it ran without issues, the temp never got above about 202°, so it seems all is back to normal.

 

Yeah these engines are different compared to the Gen I's, they like it a little on the warmer side. Low 200s is normal for 75-85 degree outside temp and 215-220 in traffic at 100 degree heat w/ A/C blasting. Some owners new to LS engines start to freak out if they see 210, but it's perfectly fine.

 

I got used to this a bit when I bought a '92 a while back, my first non-gen I vette. On a hot day in traffic it will get to 225, then down below 200 when on the highway. The LS3 does seem to vary even more than the LT1, it will get up to 220 sitting still, then down to 185 on the highway, this is with a new f-body radiator.

 

We have built a few LS swapped cars and had similar experiences, sounds like you had air in the system, you can always use an IR thermometer to verify the temps.

 

Here's a great explanation on why the air pockets will affect the LS differently-

 

So is the thought that there was enough of a void in the pump it could not build enough pressure to pop the thermostat?

 

I think you had an air pocket and it " burped" when you cracked the cap and all is fine now. I have seen that scenario before!

 

Took it out again tonight and everything was just fine. I got some groceries in it and a guy in a Mustang seemed to want to go at a stoplight when I was coming home, I spared his dignity.

 

Good deal!!!

"I spared his dignity." OK- so it wasn't my wife-