xlr857

00 Z28 has always ran at 210 degrees at the most. Within the last month I noticed it ran a little hotter but didnt overheat around 230. It would come down and go up. Today it is creeping towards the red, all my fans work, the radiator is not blocked, water pump has no seepage, thermostat seems to be working because it doesnt get hot immediatly. I popped the hood and you can hear the radiator bubbling so I know its not the temp sensor, it is getting hot. I have a code for Cat Converter so I dont think that has anything to do with it. The overflow resevoir seemed a touch low so I added some coolant and it blew it back out the vent on the cap. The car seems to get hotter with my speed if I do stop and go city driving it stays about 230, if I drive 70 on the highway it overheats. It should be doing the opposite. I am stumped any help appreciated.

ChucksZ06

iTrader: (9)

Sounds like your getting pressure in your water jacket somewhere...probably head gasket or cracked head. Should not be bubbling in the coolant. Chuck

xlr857

I tried bleeding any air out of the system it just bubbles over the top. The car will stay at 210 at idle forever, it rises when I held the throttle at 2500 rpm. I put the radiator cap back on and shut the car off you can hear it boiling in the radiator for about 5 mins after I shut it off. Is that all air or just hot coolant. The hottest I let it get was maybe 230. I dont have coolant leaking anywhere and no milky oil or white smoke, no loss of power.

Soul TKR

iTrader: (4)

hmmm... kinda sounds like a bad water pump... it could be going out... Mine did the same thing a few years back when driving the car would overheat. Replaced the water pump and that fixed the problem...

Dennis93TA

iTrader: (2)

I'm pretty sure that's a head gasket. Sounds just like the last one i had that went(diff kind of car though) The faster i drove the faster it overheated. The radiator had constant bubbles and i changed everything,water pump, thermostat, etc, and it still did it. Finally i took the head of and you could see where the exhaust gas was making it's way past the fire ring into the coolant passages. I had no oil/water transfer and no smoke out the pipe. It had me stumped for about 2 months.

Benjamin Russick

iTrader: (1)

I had a very similar problem to what you describe. It turned out to be a pushed head-gasket. I hope it is something less painful for you...

rpmauto

iTrader: (14)

how did you check your radiator flow, i had a cavalier that i put a new head gasket in and you could idle it for hours and it would not overheat, drive it at road speed, and it would get hot. Found huge deposits in the radiator. You could check its temp drop with a digital infared thermometer. Just something to check before you rip off the heads.

LS1-450

iTrader: (33)

Any white smoke out the exhaust? Any oil in the coolant? These could indicate a head gasket or block issue. If these areas are a no, then I'd go for a new water pump.

5.3LJimmy

iTrader: (10)

Sounds like a head gasket to me. The bubbling in the radiator is a bad sign. Bring it to a shop that has a sniffer to check for exhaust gas coming from the radiator. That will tell you for sure whats up.

un17real

i Agree I just let go a of a family car that had werid driving habbits and seemed the temp. guage had a mind of its own then the day i sold it the head finally cracked all the way open and looked like a 9 foot white cloud of smoke was behind it engine was then toast mixed with coolant Get it checked BRO!!

SOMbitch

iTrader: (8)

Pressure test it or have a chemical test done on your coolant. This test can pick up exhaust gas seeping into your coolant. You can buy the kit at NAPA but I would just have a shop do it cause hopefully you'll never have to use it again. Takes 5 minutes.

xlr857

Changed thermostat and cap, car is running good now, but my mechanic is still optimistic on the head gasket, he said it seems to build pressure in the hoses to quickly. Ill keep driving and see, cross your fingers.

socmguy

iTrader: (18)

Hope it's not anything too painful man. I'd swap the WP out just to be sure before pulling the head.

401rwhp

iTrader: (3)

perform a leak down test. if it doesn't hold pressure and you have no leaks then its the head gasket.

Vrbas

iTrader: (2)

Coolant in your exhaust?

Randy WS6

iTrader: (69)

I was have the same problem with over heating ,and i removed the radiator and it was full of tree leafs ,between the radiator and the AC condenser .The lower air dam is bad for sucking up trash off the road

01 BERGER CAMARO SS

iTrader: (77)

mine did the same. It tuned out to be 2 trash bags and a cat(LOL). Jus kiddin, no cat

Bluefields88

I just got a FAST intake put on my car today with LS6 coolant lines, and now it's having the exact same problems. bubbling in the radiator and everything. any help???

wicked z28

iTrader: (9)

My car started doing the same thing after I swapped to an ls6 intake and coolant lines now that I think about it its been years now and It still overheats if i turn on the ac on a hot day and drive for awhile.With the ac off on a normal day it just gets to the 210 mark but for some reason when I warm up the car I feel it gets to the 210 mark faster than what i feel is normal.Ive replaced the waterpump radiator and 160 thermostat and coolant temperature sensor on the head and the same thing,but no smoke or milky stuff on the oil cap or water in the oil.I wonder if it has a slightly bad head gasket or crack on the head or the ls6 coolant lines.

eallanboggs

iTrader: (1)

You going to be damn lucky if it's leaves or a trash bag, but it doesn't cost anything to check. I agree with the leak down or compression check. Look for <10% differential.