Themonkey209

So I own a 2000 z28. I have a new radiator, new cap. It does not over heat, oil looks good and coolant seems to be fine with no oil. At times after driving it does get to about just a centimeter above the middle. Once I turn it off coolant begins to boil from the radiator & overflow. (Sometimes coolant comes out from the overflow tank) so I'm planing on changing my thermostat and flushing the coolant for air.. Would a bad thermostat cause this??? I would feel so much better if it's just the thermostat but idk if this is a symptom of a bad t-stat. So I'm going to also do a block test as well just in case.. Any advise? Has Anyone had any similar issues ??

fleetmgr

Regardless of what the temp gauge says, your engine is overheating. From your description the thermostat is the likely culprit.

demonspeed

iTrader: (7)

Definitely change the thermostat. I would highly suggest removing the power steering cooler while you're messing with the coolant system.

A note about the thermostat: you'll find there are two types -- one with the housing, and one with just the thermostat. You'll want the unit with the housing if you've never replaced the water pump. The setups that require just the thermostat itself are 2004+ pumps which is the OE service recommendation for water pump replacement.

edit: comment on the temp gauge -- the only year that offered a "working" gauge was 1998. 99-02 were essentially just an on/off switch, showing normal temp without fluctuation at all times unless it was overheating. If you have movement, then it's overheating no matter what it "reads." Also, you may want to consider replacing the coolant temp sensor depending on the mileage.

wssix99

iTrader: (5)

How about a bad pressure cap on the radiator? If this was bad, the system would see atmospheric pressure and would boil at a lower temperature.

I'd think this would be more likely than a double failure of thermostat and coolant sensor.

I'd also get a hydrometer and test the coolant.

demonspeed

iTrader: (7)

I should ban you for your inability to read.

Themonkey209

Awesome! Great Thank You! i will Most Def change the T-stat ASAP., so from the sound of whats happening to it., would a Bad T-stat cause that ?? im really hoping its only that., i am hoping it isnt a bad Head Gasket!!

TASCAPARTS

agree....
Since you have replaced all the rest... oem ones form us run $ 36.00 plus shipping but I wouldn't wait..

Chris

wssix99

iTrader: (5)

Crap.




I read that the first time and then forgot when I came back to the thread.

I still think this is a pressure problem. In order for this to be overheating, there would need to be a simultaneous failure of the temperature sensor and thermostat. That would be highly illogical: (but still possible)



I'd:
- Throw away the new radiator cap unless its a GM part.
- Do a pressure test of the system
- Test the thermostat and temp sensor before buying new ones:
~ http://www.focushacks.com/mod/Testing_your_thermostat
~ http://www.wellsve.com/sft503/counterp_v2_i2_1998.pdf

LS6427

iTrader: (2)

So....it only starts to boil out of BOTH the radiator AND overflow tank....AFTER you shut the engine off....?

It does not ever boil over with the engine still running...?

If your tstat was not opening the temp needle would never stop moving and it would bury into the red.....all the way to the right.

Maybe you crossed the coolant cross-over line coming from the TB/heads.....with the over-flow tube port.......

I guess your tstat could be partially opening......but if its boiling over you have AIR in the system.....that's for sure.

Could be as simple as a bad NEW Radiator cap.........it happens. But check that the overflow hose is running to the overflow tank.....and the coolant cross-over line is running to the port UNDER the overflow port.......

.

lsexpress

iTrader: (-1)

I had this problem before I forgot what fixdd it

RPM WS6

iTrader: (3)

I think the issue will more than likely come down to either this:

...or this:

Based on the description so far, I think the t-stat is much less suspect than the other possibilities above. But it certainly wouldn't hurt to test it.

demonspeed

iTrader: (7)

And likely not a bad idea to change it, anyway.

Themonkey209

Super valuable info everyone!! Thank you!!! Wish me luck!!! I have picked up a combustion leak tester from Auto zone and am ready to do a little chemical experiment!!! I am so crossing my fingers this blue liquid stays BLUE ! And doesn't turn YELLOW!!!! (Or green according to a few YouTube vids)

perezpowerbuilders

+1 on the radiator cap..my car was doing the same thing boiling and sometimes overflow from the reservoir took me awhile to figure out the problem. Turns out the radiator cap was not holding proper pressure. I replaced the old one with a new one and the new one was bad too! Took it back and got another one . Fixed the problem.

joecar

I've had new rad caps that were bad.

qwkhuh

same thing just happened to my car on sunday

hrcslam

Ohh looks like it's been covered. Just because it's been replaced doesn't make it good or the right part.

demonspeed

iTrader: (7)

No, but I like to find reasons to give wssix99 a hard time.

wssix99

iTrader: (5)

The suspense is killing me. I am looking forward to finding out what the resolution is here so we don't need to entertain ourselves with this childish bickering! (Maybe we should start a separate thread for childish bickering?)

demonspeed

iTrader: (7)

I, too, am interested in knowing how the problem gets solved.

I am also interested in bickering since things are slow at work today.