This is a ’97 Firebird w/~80k miles,WS6,LT1.
Unfortunately it sits more than I drive it.

The last few times I have had it out, it has been overheating.
Sometimes just spikes, other times it will get close to overheating before I turn it off.

The first few times I checked the coolant and found the radiator very low.
Then I decided to check/fill the reservoir (should have done that in the beginning).

The coolant reservoir was loose and “free floating” – I could only touch and see the neck w/out taking it apart.

I tried to remove it from under the car. That was a mistake – talk about a never-ending air dam to try to get apart...
then I figured out it was removed from above...

Here is a pic. The reservoir is supposed to be attached to the battery pedestal – but mine has separated.



Could this cause an air leak in the coolant system and be my problem?

Can I “plug” the reservoir in/out at the top of the radiator neck & test it?

Btw, the oil is clean and I don’t see any odd smoke coming out of the exhaust.
Not sure where the coolant is going? From underneath, I saw no other leaks.
No bad hoses that I could see from the top or bottom.
I hope I don’t have deeper internal problems?

I am not the best at describing (& missing) things on a message board.
That said, any advice is appreciated.

Any coolant odor inside the car? Passenger carpet dry?

I had an '84 and still miss it sometimes.

No coolant/odor inside Mike - matter of fact, when I was running it the other night in the driveway, I ran the heat/fan on high while it started running hot.

Just cool air came out. I always thought this was sign of low/no coolant.

(This was before I pulled the reservoir btw)

Me too. So the reservoir mount is somehow broken, but you're saying the radiator is also low? Methinks the reservoir is leaking.

Losing coolant, no obvious leaks.

Slowly overheating, no heat from the heater core (low coolant).

sounds to me like you are losing coolant into the engine = blown head gasket - although you say you don't see any white smoke it may be hard to see.


There are a few vehicles that can get an air pocket in the cooling system that you have to release manually - I'd be surprised if this is one of them, but it might be worth a look.

I used to have a gm truck that had the intake gasket replaced a couple of times. first sign it was needed was disappearing coolant.

Coolant has to be going somewhere. Either it has a leak or an intake problem.

Appreciate the input guys...
While I was hoping for everyone to say the coolant overflow was the problem....
all signs point to deeper problems...

Next step: replacing the reservoir – then figure out where the coolant is going....

Have you replaced the simple things like thermostat & radiator cap? Then go from there & see what happens. You say you don't drive it often maybe something simple will be a fix.

I wouldn't just randomly replace. Figure out what's wrong then fix it.

I hear you Indy – but I disagree.
When it comes to small/inexpensive/easy things that I have not replaced on the car – why not do it first?

I pulled the thermostat over a month ago.
I could move the spring with a screwdriver – so I put it back.
(not sure if that means it was good – but it seemed OK to me).

Since I am buying a new coolant res, I might as well buy a new cap and thermostat.

Looks like it was the thermostat.
I am thinking the disappearing coolant was lost through the broken reservoir while overheating?

Last night I went to my local parts store.
I asked for prices on a new cap, thermostat & reservoir.

Thermostat ~$9-20
Radiator cap ~$5
Reservoir ~$50 (not on-hand, ordered - I also found some online for $32 and up).

When I told the guy at the counter the problems I was having, he suggested I buy the cap, the reservoir and just remove the thermostat.

(he isn’t the first person who has told me they never use a thermostat in FL)

I ended up buying the cap and headed home to attempt to repair the res.
After drilling some pilot holes in the top (battery tray), applying ample 4200 (boat tie in) and a few screws.... it seems as good as new.

I put the res and battery back.
Started it, filled the radiator and res.
As I watched the temp gauge go up, I could see the coolant staying up (radiator cap of).
I shut it off when it started to overheat.

Then I removed the thermostat, took the gasket off the thermostat, and only put the gasket back in.
When I started it, the coolant started circulating after a few minutes.
I say “coolant” but it is all water at this point.
I topped the radiator off, put some more water in the res.
I ran it in the driveway for half an hour without it over heating.
When it finally did get up around 230 or more, I heard the fans kick on so I know they are working.

I will know for sure if this was the problem after I drive it the next few days.
If it works, I will drain it & put some antifreeze in.
(Btw, I have an unopened radiator cap to return)

Thermostat question:

I have heard of people never using a thermostat here in FL.
We don’t use the heater very often and when we do (me anyway), we never need immediate heat. read: on a 35 degree morning, I can wait 10 minutes on the way to work for heat – I won’t freeze.

I have also heard that you should always have a thermostat in so the engine gets to operating temp quicker, like it is supposed to.

Any thoughts having or not having a thermostat?

Unless you like throwing money away on wasting fuel, polluting the air more, and wearing your engine out quicker, I'd suggest using the OEM recommended temperature thermostat.

Many OBDII vehicles will set a P0128 code for a stuck open or missing thermostat, which is failure for the engine to reach normal operating temperature in a specified amount of time.

I can be hard-headed some times – but you are loud and clear cny.
Thanks for the explanation

I feel kind of dumb after asking.
After that last post, I did a web search on “do you need a thermostat in Florida”.
I found similar responses to yours from other smart guys... some not nearly as friendly as you.

As for the car: I took it out for a ~45 min drive today.
The temp gauge starts at 160, top/middle is 210, the end is 260 (overheating).
In some slow traffic/stop lights, it got above the midpoint, 220 or so.
Then while driving above 20 mph it stayed in the middle of the gauge.
The coolant level was still good after that.

Thanks again to those who posted.

Indy, I hope I didn’t come across disrespectful in that post.
Sometimes when a not-so-smart guy is asking questions (me), the basics are a good start.

Hopefully a new thermostat and fresh coolant will be all I need now.... lets hope.

Your temps will be cooler with a thermostat than without. The thermostat slows the coolant down and without it the coolant does not stay in the radiater long enough to pull the heat out.

In race cars where you want to eliminate all possible failures, (like a stuck thermostat), they use a flow restrictor. It's basically a washer instead of the thermostat. Slows the flow but no moving parts to fail.