Tev22

So my full bolt on Z is starting to overheat. Usually runs under 200 degrees but for some reason over the last few weeks it has been creeping higher and higher till yesterday it got up to 240. I checked the fluid level and it looked fine. Fan is coming on and blowing. Nothing on the radiator. Could the thermostat be stuck? Had a 160 degree put in when the heads were fixed about 10 months ago.

Landru

Fan works so it isn't the notorious burned fan connector.
Guess thermostat might be going south, water pump also.
Also recall owners w/ your kind of build had to go with an aftermarket radiator to get more flow.

G/L, keep us posted what you find's the culprit.
Hopefully it won't be difficult identifying/tracking down the issue.

RedZ4me

Hopefully just a stuck closed t-stat. Other things it could be, rad- poor flow - water pump? Hopefully not a head gasket.........have you checked the oil condition for coolant mixed in? and how 'hard' are the coolant hoses under operating conditions?

Tev22

Yes I checked the Oil as well. Looks good. I haven't checked the hoses.

rjacobs

stuck thermostat or bad pressure cap on overflow tank would be the first things I would check. If the system cant build pressure the system cant operate correctly.

Down that list would be water pump(they are pretty reliable) then system flow issues(which I wouldnt suspect, especially if you had the system drained a year or so ago so you have fresh coolant in it).

A bad ECT sensor COULD cause the issue in the gauge, but I would doubt it. If its like the oil pressure sensor it would either spike full hot or full cold(not sure the failure mode of an ECT sensor). You would also get some messages on the DIC.

MTPZ06

T-stat sounds suspect, but also make sure your rad fins are clean and free or debris. Common for tem to become clogged and should be blown out with compressed air now and then. Also think it may be a good time to upgrade to a better rad with your build...but that's not your problem at the moment IMO.

stefuel

Thermostats are fairly cheap and a good starting point You can test it. Take it out and put it in a old pan full of water. Put a meat thermometer in the water. Put it on the stove and see what temp the t-stat opens. That pretty much takes the guess work out of it

vertC6

Did you see a difference when adding the 160 thermostat?

outhouse

Absolutely. 180-190 cruising winter temps.


But pushing it temps will be identical.


For winter usage I'm not sure its a good idea as it takes a while for oil to get to temp almost too cold, for summer here absolutely a good idea.

MTPZ06

Was going to say that...couldn't stand that in stock form myself. That's why I upgraded to the ZR1 oil cooler and OE ZR1 rad. Better cooling that the OE Z06 rad, and much faster oil heat up.

vertC6

That's what came stock in my 13' 427 so I don't have to swap the oil cooler!

MTPZ06

Yep...'11's and up. GM saw something there, so I wanted to replicate it.

outhouse

Since its my DD I end up driving most of the time between 1500-2000 rpm.


If I was beating on it more often I would definitely switch rads like you.


Almost need a gate valve for seasonal adjustment.

MTPZ06

In your application, your could pretty much just swap in the improved racing thermostatic oil block, and then you just need to convert the oil cooler lines to AN fittings, and call it done.

Tev22

Well it was the thermostat! Swapped it out with a new one and everything is back to normal.