Hey all. Back in February of this year, I bought a 88k mile 1995 Camaro Z28 with the LT1 automatic and t-tops. After replacing the rear end (bought it with bad rear gears, decided to replace whole) it was all smooth sailing until the weekend of July 4th.

As I was driving down the interstate to a car show, I realize that the car is overheating. I quickly pull off the road and find that the lower radiator hose blew at the connector. (flow control restrictor maybe?) After replacing it with a standard hose connector, I noticed that it overheats EVERY time you go interstate speeds for more than five minutes. I simply avoided interstate and tried to sus out the issue (new thermostat, coolant flush) but last week, after a PROPER coolant flush, it has decided to not stay cool AT ALL anymore. I can't even drive it for two minutes at any speed before it hits the red. The thermostat is operational, my oil is clean and not milky, and I'm not blowing blue or white smoke at all. One thing I did notice is that the passengers side radiator hose going to the water pump is lukewarm at best even when the car is overheating, not hot like the driver's side one. However, I still cannot find the source of the problem and would prefer not to throw the parts cannon at it quite yet. Please help me out - it's my DAILY.

 

sounds like a failing water pump to me

 

I agree with the water pump as a culprit along with a clogged radiator and/or heater core. With the cap removed and the engine running you should see coolant circulating in the radiator. Trapped air can cause overheating issues too so when you do the refill elevate the front of the car and add coolant slowly until filled to avoid trapping air inside the engine.

 

I have had a water pump fail where it appears to be spinning properly but is not pushing any coolant inside so 100% a possibility. Other then that vacuum fill the system with coolant to take air bubbles out of the question and combustion leak test to take internal coolant leak out of the question

 

Also when I had a water pump failure it was smooth sailing on interstate then all of a sudden temp went up up and away

 

Isn't there a bleed valve to get all the trapped air out that gets trapped in the LT1 cooling system? I seem to recall one on my '94 Z28.

 

Used that bleed valve several times. Seems to just keep creating pressure / sucking in air somewhere. Will spurt out air and then coolant repeatedly when foot is on the gas which is what had me thinking either really pesky air pocket or headgasket.

 

Yeah, looks more and more like that water pump is giving up, or there is a severe blockage somewhere in the system.

 

I had a 1995 Z28, had a couple of issues with stuff and crammed in a 408ci LS Stroker Engine. That was a good decision.

 

Just installed new water pump. Put everything back together, filled with Dexcool and bled for air bubbles, drove it five minutes out and it was fine. Get back to the shop... temp guage is bouncing from 1/4 to 1/2. Turn the car off and immediately hear hissing and bubbling. WTF is it with this thing????

 

Have u done the combustion leak test with the blue dye? None of us want to know when it's happening but it's better to know for sure ASAP. also the way to get air out of the question is use a vacuum fill kit. Buddy of mine had that going on where it was gurgling and temp fluctuating on ls1 car. We drained coolant and vacuum filled with my kit. Immediately stabilized

 

agree with the above comment. also, perhaps time for a new rad cap?

 

I started it up again probably five minutes after this was posted with cap open, bled it again, did the radiator test (fluid changed to a slight teal color but not yellow) and then drove it home without a single overheating problem. Actually COOLER than it usually ran before then. Maybe I am just... impatient. Thanks guys, I'll let you know if it comes back. No idea what I would do without y'all.

 

U got this brother sounds like a nice low mileage Camaro u got

 

LT1s are reverse flow cooling - so you need to spend extra time bleeding the system. Most of your issues point to air pockets - but it sounds like you might have finally got them all out. I always drill 2 small holes in my T-stats (1/16") to allow coolant circulation while the engine is cool which makes for much easier bleeding. This is a unique requirement for electric water pumps where you shouldn't dead-head the pump.

I would also change out the other rad hose if the lower one blew off and they are/were quite aged.

 

Good job on finding the solution. The lt1s require a special bleeding process not like normal cars as mentioned above, other wise they love to overheat. Also just incase, make sure the air damn is there on the bottom of the radiator.