LazyLemming

I'm currently having overheating issues in my Z. I've posted another thread about it before here

https://www.camaroz28.com/forums/sho...lant%3F&page=2

To keep it short, it is STILL overheating, the radiator is a single row 1" tube, it has been tested for pressure and flow and tested okay. Thermostat, sending unit, water pump and guage have all been replaced. The heads were checked by a mechanic and are in fine condition. Coolant came out looking brand new, and has been flushed. It IS flowing. Air Dam is in great condition and nothing is blocking the radiator. Engine runs great, idles smooth at 600 and 5000 RPM.
It still hits 250 degrees now.

Mechanic flat out told me he has no idea after almost 3 weeks of working on it. He's the third mechanic.

Buddy of mine used to tune and race muscle cars, he hasn't looked at it but thinks the radiator can't handle the summer heat here in Yuma AZ. It makes sense as when I bought it temps were 80-90 and are now over 110 (116 today). Before I drop 600+ bucks I don't have at the moment on a two row radiator, does this sound right to you guys?

Any other advice?

Injuneer

Why not just put a stock radiator back in it? Does the aftermarket radiator have the correct connection for the steam tube return from the back of the heads?

LazyLemming

http://shbox.com/1/95-97_hoses.jpg

Okay I do have the steam return line (#6 right?). It looks someone did the throttle body bypass described here http://shbox.com/1/tb_bypass.jpg

Also of note all my heater hoses have been cut, with a short hose and bleeder valve connecting the two outlets Even the throttle body heater inlet hose is cut.

Injuneer

If the throttle body bypass was done correctly, elbow #4 was removed, the coolant from tube #6 will connect to hose #5, which connects to the nipple on the radiator right below the fill neck and overflow nipple.

What is confusing is your statement that "the throttle body heater inlet hose is cut". Do you mean that rather than fully remove rubber elbow #4 from the passenger side coolant connection on the throttle body, that they just cut it off, leaving a piece of it connected to the throttle body?

Also, describe what your heater hose routing looks like, using Shoebox's diagram:

http://shbox.com/1/heater_hoses.jpg

Have you verified that all the other coolant hoses are routed correctly?

LazyLemming

heater_hoses.jpg?t=1278083480

My heater hoses look like this. The green line indicates the new hose, the blue scribble shows where the old heater hoses are cut. Your description of the rubber elbow is correct. A small piece of tubing is left on the passenger side of the throttle body. The drivers side of the throttle body is capped off.

And yes, using the shbox diagram as a guide all the other hoses are routed proper assuming the bypass linked above.

Injuneer

Do you still have the flow restrictor (#13) in the circuit?

LazyLemming

I will have to check when I get home from work.

LazyLemming

No, I do not have the flow restrictor. The hose connects to the lower nozzle, runs almost straight up, connects to the bleeder valve and then another hose into the upper nozzle.

LazyLemming

I took it out for a looong test drive tonight with a scan tool connected. All temps were checked by the scan tool, with the gauge reading similar the entire time. At worst the gauge displayed 6 degrees above the scan tool.

I started off idling it for almost an hour, with the PCM showing 217. I then drove a couple blocks and picked up the back highways. After about 15 miles it was down to 202 and spent the next 10 miles between 202 and 208. Then I hit the city and it went up after a couple miles to 217 and hovered there for another 10 miles. I brought her home at 214. It's highest temp at the pump was 223 immediately after climbing an extremely steep hill in the city. It dropped back to 217 within a few minutes after that.

Ambient temperature was low 90s at night.

I'll try it tomorow during the heat and see how it reacts, but this makes it seem like the cooling system is working, just not optimally. It's always been a hot day when it overheated and it didn't start to overheat until a month after I got it, when it started getting hot here.
My theory is that with it scooping 130 degree air off sun baked pavement, it's just not efficient enough to cool it, perhaps simply due to wear over time on the cooling system. Does that make sense?

Injuneer

Why did you change the radiator to the 1" single row?

LazyLemming

I did not, that's the radiator that was in there when I purchased it. Most likely a previous owner replaced the radiator with the cheapest thing he could find.

Injuneer

It should be very low $$ to find a used stock LT1 radiator, have it cleaned and install it. That would tell you if the radiator that is in there is too small. Seems odd that they would find an aftermarket radiator with the correct connection for the steam tube return.

Bobsep84

Are you hitting these high temps while sitting at idle or while driving? The fans on these cars are programed to turn on at a pretty high temp so the temp will increase quite a bit when sitting at a stand still (3/4 up on the dash)....but drop down to 180 or so while driving...about 1/4 up on the dash indicator....