ColoradoZ28

Hey all, new to CamaroZ28.com and looking to get some help. I recently inherited a 1994 Z28 LT1 (60,000 miles) Six speed manual. The car has been in Santa Barbara its whole life and I recently drove it up to Colorado where i live. The vehicle had radiator service and hoses replaced before the long drive back to CO. The car had no problems on the drive. When i arrived, I installed a K&N intake and Trickflow Specialties elbow to clean up under the hood. Ever since the install i have had problems with the vehicle beginning to overheat. Any advice on the next step to take? I've been told by some friends with slight mechanic backgrounds that the Comp may need to be adjusted with the change in altitude, as well as thermostat being thrown off from K&N install. Pretty new to performance cars....Appreciate any advice. Thanks!

shoebox

Explain your overheating scenario. It may be normal operation. The computer automatically adjusts for altitude and the K&N would have nothing to do with the thermostat.

Injuneer

+1 on Rob/Shoebox's questions.

Are you running the correct mix of coolant/water? Have you checked the cooling system to insure it's holding 18 psi? Water boils at a lower temp when altitude increases. It needs the right mix of water/coolant, and pressurizing the system to prevent boiling and the resulting poorer heat transfer.

ACE1252

In addition to what Shoebox and Injuneer mentioned...

When the engine is stone cold(sitting for 8 or so hours to get cold), first check the coolant level in the overflow reservoir(next to the front passenger's fender with the hood up...about 5 inches from the battery). Is the level between the min and max marks? It should be...normally, should be around the min mark(when the engine is fully warmed up, this level will get close to the max mark).

Next take the cap off the radiator....is the radiator full? It should be...if not then the system was not serviced correctly or you have a leak somewhere.

The reverse flow coolant system of the Gen II LT1 has a certain way to fill the system. If not followed, then air can get trapped in the system and cause cooling issues.

There could be other causes, like the cooling fans not turning on or more serious issues....but need to check the simple things first.

Note where you find the levels above and report back what you find.

Fatdog2

Check the clamps on the radiator hoses.Been down this road before.You won't see any leaks until you use a radiator pressure tester(free for loan at Autozone).But if you can get a cheap set of sockets do your own tightening as tight as the clamps will go.They may seem tight but believe me they are not.Also,every car I have ever owned,after a radiator flush,the next morning either the radiator was low or the overflow tank was almost empty.Also like Ace 1252 says that air gets trapped so there is a screw on the top of the hose that can let the excess air out.(in front of the alternator ).Please post back your results.Hope this helps.My02.

Fatdog2

Sounds like a real nice car,congrats.What color?

ColoradoZ28

Thanks for the replies all.

Shoebox: when driving for about 20 minutes on a normal Colorado day, about 70 degrees outside, the temperature gauge starts to climb to right around 235, right at the cusp of the redzone, sometimes going into it. When i notice this i start to drive pretty easy and the temperature drops a little to around 220 - 230ish. Not sure if this is the normal temp LT1's run at? Hadn't really paid much attention to it on drive from California.

Injuneer: I am not sure of the exact mix of coolant. I had just paid the shop to do the flush and replace the hoses before i drove it from CA... Is the mix ratio something I can check?

ACE1252: Radiator is full when sitting cold. I have opened the bleed valves and noted a solid flow stream. I wont have time to drive it till this weekend, but i will check the fans then. I think this could possibly be an issue as i haven't noticed or heard them kicking on when the engine is hot and idling.

Fatdog2: I will tighten all the clamps and check the overflow tank this weekend and go get a pressure test done. I will also post pics of my new LT1! Very Excited!

Thanks!

Injuneer

Stock tuning turns the fans on:

First fan (early model year 1994) or both fans low speed (late production) at 226*F.

Second fan (early) or both fans high (late) at 235*F

Since you indicate it didn't get over 235*F it sounds like the fans are operating as intended.

Test the mixture with a hydrometer (aka - "antifreeze tester"). A suction bulb and tube with an indicator (often a float or a few *****) that shows the approximate water/coolant mix, compensating for the temperature of the sample. Less than $10, some under $5. You want 50/50 for max protection against freezing and boiling.

While driving at any decent speed, gauge should read toward the middle (210*F). Sitting in traffic is usually when you see temps significantly above that.

Check the front of the radiator to make sure you didn't pick up some debris like a plastic bag. Make sure the air dam under the front bumper is intact. If that's missing, temps will rise quickly, the faster you drive. The dam pushes the air up into the slot formed by a black plastic baffle and the front of the AC condenser/radiator.

ColoradoZ28

Fred, That was it! When installing my K&N i had taken off the air dam along with the other coverings. Installed the coverings back on after K&N install, but not the dam. Frankly, i was unsure what use it had other than snagging on curbs when i pulled up too far.hahah. Took er for about an hour drive this afternoon and had no problems when driving quick. Actually stayed below the standard temp. Thanks for all the advice everybody!

Injuneer

Shop left mine off after some mods and tuning. Driving home on the Interstate at 70 MPH coolant temp started to rise quickly. U-turn back to the shop.

ACE1252

I think the cooling fans will not turn on up around 65-70 as they become a hindrance to airflow if running.

Good catch gents. =)

shoebox

When I have my a/c on, they will shut off after 35-40 MPH is sustained for a short time.

Osvaldo

Can my z28 94 get over heading becouse i dont have a thermostat in it

shoebox

It could. You should not run an LT1 without a thermostat. It directs the coolant to the right places at the right times. It is not like a simple open/closed SBC thermostat.