Dirty Howie

My coolant maxed out at 260*, with DIC warning that coolant temp was too hot, and heads up display to check guages. This happened 3 sessions in a row after about 4-5 laps.

This has never happened before, although I don't really know what my coolant temps have been in the past. I have ran this same track in much hotter conditions without this issue.

Keep in mind the car has 83K miles. Coolant temps seem normal on street today...... 196 crusing, 216 in stop and go gridlock.


Here are the possibilities that I can think of. Please comment from experience if possible.


1. My air damn is worn

2. I took the rear hood seal rubber piece off to let hot engine air out (have done this before but don't really know if it helps or hurts)

3. oil cooler and radiator clogged. Radiator definitely needs to have fins cleaned and I am going to buy a new oil cooler unless its fins which look bent can be properly straightened and unclogged

4. Recent oil pump replacement damaged cooling components or radiator shroud not installed correctly allowing air to pass

5. Just need new coolant and flush, unlikely

Notes:

There was no loss of fluid even though it was overheated.

Removed the plastic piece to see between radiator and condensor. There definitely was debri in there but nothing big. But someone noted that the condensor was bowed, not straight .... possibly bent?

When I got home I noticed that there is some play in the radiator shroud. Don't know if this is normal and should be very tight fitting.

Something has changed and is wrong


DH

'06 Quicksilver Z06

Indeed. And that's why we have to keep this in perspective. 83,000 miles on an LS7, daily driven and with numerous track days on it, is damn good. If you really think about it, 83,000 miles, heavily tracked and daily driven, at this point, every day it runs is a blessing.

83K miles, multiple track days, it could be anything.

"1. My air damn is worn. I'd start there. With 83K miles on it, no doubt the air dam could use replacing if it is the original air dam

2. I took the rear hood seal rubber piece off to let hot engine air out (have done this before but don't really know if it helps or hurts) I doubt this makes a difference.

3. oil cooler and radiator clogged. Radiator definitely needs to have fins cleaned and I am going to buy a new oil cooler unless its fins which look bent can be properly straightened and unclogged. With 83,000 miles on it and a *&^+load of track days, it could probably use a new radiator too.

4. Recent oil pump replacement damaged cooling components or radiator shroud not installed correctly allowing air to pass. Another good place to look. I'd look there while I was looking at the other possibilities.

5. Just need new coolant and flush, unlikely. If you are going with a new radiator, you can do this before the install. I trust that the fans are working properly."

jmorgan07z06

Maybe time for a new water pump as well

'06 Quicksilver Z06

phxcobra

I think taking the rubbber piece out could have negative effects. I think that area is high pressure and would suck air in (think cowl hood). That could increase pressure behind the radiator slowing air movement through it. Might be neglible, I dunno. I'd put it back. If you want to vent, get a vented hood with vents/louvers farther down the hood where the pressure will be lower.

Dirty Howie

Fans are working as they were on when I pulled into the pits and they remained on for a while.

It is the original air damn. Looking for confirmation that this actually causes a cooling problem.

Its hard to know if this has slowly been becoming a problem since I have NEVER monitored my coolant temps or if it is a direct result of the recent work done on my car. I did track it since the repair but it was in a cooler environment.


DH

Dirty Howie

Now something like that could be failing. Would it just show in extreme track conditions. Like I said street temps are fine.


DH

Dirty Howie

It will be on from now on. Not getting a hood. This is a new problem not present for last 3+ years.


DH

jlvink66

I had exactly the same experience that you had. I was surprised when I found out that it was primarily all of the little bits of track debris, mainly fine gravel and small rubber turds that plugged the radiator up.

I attached a 16" piece of copper tubing to the end of an air nozzle, pulled back the rubber piece and blew air between the condenser and the front of the radiator. I was amazed at the huge amount of small debris that came out of the radiator. If you pull the radiator out, you could obviously do a better job of blowing the debris out from the other side, but I wasn't up for that much disassembly.

I did the above plus replaced the water/glycol with 100% water plus some Watter Wetter and my overheating problems on the track went away.

John

nhpln

Howie, you can rule out #1 (airdam worn). Unlike the C5s and base C6, The C6 Z06 is entirely a front breather. The center airdam on C6 Z06s is for aerodynamics. The side pieces direct air into the brake ducts.

Z11409

Spray condenser and radiator with engine cleaner and was out debris from the engine side of radiator.

Dirty Howie

John

Which rubber piece are you referring to?

What does your oil cooler look like ?


DH

Dirty Howie

Yes but isn't possible that the worn air dam lets the air pass under the car so freely that some doesn't get forced in the front breathing area?


DH

Dirty Howie

Have you done this? What cleaner did you use? Did you disassemble the radiator/cooler. How do you wash it out?

Did you do this for oil cooler as well.


DH

BLW BY

Once you overheat a precision engine, like the LS7, IT'S TOAST.

Tolerances and clearances that were once precise are now, well you know, TOAST.

You can chase your tail until you're dizzy but the end result is;
You've overheated and now distorted all the tolerances, so now everything is building heat. Daily driven doesn't make heat like the track.

Just my $.02

R

nhpln

Nope, look at the opening just above the air dam. It is blocked by a piece of black plastic. On the base C6s, it is not blocked. Hence, C6Z = 100% front breather.

Hercules Rockefeller

Not every thread about something going wrong with a Z06 is an invitation to jump up and down and prove the car isn't to blame. Just give it a rest already.

Don't listen to this guy either, first of all there's not way he can know if you've actually overheated your engine enough to damage it, and given that you still had coolant in your motor, it's pretty unlikely. Most likely if you had really overheated your motor while driving at the track you would know

It's also not your air dam, like nhpln said, the C6 Z06 is a front breather, the air dam isn't your problem. It could be the ducting around the radiator... it is strange that it's happening right when you had the oil pump replaced, but still it seems unlikely. Your radiator could have a blockage, or your water pump could be screwed up.

Here's what I would do: I have a spare OEM radiator and water pump, so why don't you throw them in your car, and fill it with DI water and a bit of water wetter, and see if that solves your problem. I think that will solve your problem and get you all fixed up. Make sure you check the ducting when you're replacing the water pump and radiator and you've eliminated most of what could possibly be wrong. I've got your solution sitting in my garage, you can come by and pick it up along with some of the Corvette Challenge T-shirts!

Oh I forgot to mention: leave your hood seal off, the seal does NOT help lower engine temps; if it did just imagine how bad the overheating problems would be with louvered hoods! The lower the pressure behind the radiator, the faster air moves through it, the better it works. More airflow is always better for cooling... always.

Dirty Howie

This seems a bit out there. What do you base this on. Shouldn't the DIC have said "coolant temp too high - replace motor now". I ran 3 sessions where this happened and the motor seemed to run normally.

If my motor is toast what should I see ........... ??


DH

Dirty Howie

HR

Hope your right about no engine damage. Some of the other guys were running 237* coolant. I can't imagine 23* more would kill a motor but I really don't know

Did you mean to say leave hood seal ON .... your statement seems to be contradictory

Thanks very much for the great offer. I am going to talk to dealer and see if there is anything they can do or check from the oil pump replacement.


DH

phxcobra

When trying to vent hot air from the engine bay you have to look at the pressure zones. you only want venting where pressures are lower so that air is drawn out. I'm not sure you want and opening at the back of the hood (by windshield). Again, why do you think cowl hoods have their opening at the back. Typically there's high pressure in that area because the air velocity is lower in that region. Again, it's probably tiny, but you aren't going to draw air out back there. I still contend your more likely to pull air in. Maybe some one from Katech or LG can chime in since they know aero. But look at the louvered hoods, the vents are farther down on the hood where air velocity is high/pressure is low so air is pulled out from the engine bay. you could always do the string test to confirm what the air is doing back there.