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Help! LT1 coolant leak, or just overflow?

adamschorr

Member
Joined
Sep 19, 2001
Messages
15
Location
Westport, CT.
Corvette
'70 LT1 conv't; '99 6-speed coupe
i just replaced two heater hoses and flushed the radiator and cooling system of my 1970 LT1. i drove the car (kinda hard in 75 degrees) for about 20 minutes and parked it. it started LEAKING COOLANT from an area close to the passenger side fire wall...after 15 minutes it stopped dripping.

did i overfill the system?

i believe there's no expansion tank on this car. i checked the clamps to see if something was loose. all appears okay.

what happened? how does and LT1 discharge coolant, and, from where?

thanks for your help!
 
7

72LT1Steve

Guest
Adamschorr;

Well your right that there is no expansion tank on the LT. The overflow is located just under the radiator cap on the neck (at least that is where mine is). There should be a smaller diameter rubber hose attached and it should drop over/down the side of the radiator. That's where any overflow discharge should occur. As far as overfilling the system, if done, it should disharge at the overfill hose and level out.

Now the dripping at the firewall area, there shouldn't be any. Couple possible problems I can think of:

1. The heater core neck(s) had/have some corrosion on them and are not allowing a clean seal of the new rubber hose around them/it.

2. Possibly a crack/pin hole developed in the heater core neck during replacement and under the pressure allows the drip.

In both cases I can see as the engine cools and the internal radiator pressure drops the drip stops.

My radiator water level in approximately 1 1/2 - 2 1/2 inches below the radiator cap. I would think yours should be similar.

Good luck!

Steve
 
J

Jeffro

Guest
Leaking Coolant

I'm going to have to agree with 72LT1Steve.

Most likely, there is a pin hole of crack. It probably existed before but was agravaited by the flush. It happens.

My coolant is about one inch below the cap.

What kind of temperatures are you running on average?
 

adamschorr

Member
Joined
Sep 19, 2001
Messages
15
Location
Westport, CT.
Corvette
'70 LT1 conv't; '99 6-speed coupe
thanks guys. i just got the car.

previous owner did a body-on resto 12 years ago, and only about 2-3,000 miles since.

i'm still getting to know it's quirks, and it was important to check/replca basic fluids as a new owner.

car is running VERY cool. the temp gage works and indicates not much over the 100 degree mark. moves a little to the right towards 130-150 degrees?

for the 11:1 motor, i've been running full tank of 93 octane mixed with 1/2 bottle of "Maxlead 2000". i read it lowers temps, lubricates and boosts octane.

mechanic said he pressure tested the system with the new hoses and there were no leaks. so, not sure why leak was dribbling down firewall/heater core.
 
0

0018

Guest
adamschorr said:
i just replaced two heater hoses and flushed the radiator and cooling system of my 1970 LT1. i drove the car (kinda hard in 75 degrees) for about 20 minutes and parked it. it started LEAKING COOLANT from an area close to the passenger side fire wall...after 15 minutes it stopped dripping.

did i overfill the system?

i believe there's no expansion tank on this car. i checked the clamps to see if something was loose. all appears okay.

what happened? how does and LT1 discharge coolant, and, from where?

thanks for your help!

Adam,
I put a coolant overflow on my '72. It helps keep air and rust out of the system and allows more coolant in the system. I also decreased the pressure to 10 pounds with another radiator cap (too much pressure is not good for the radiator). You can mount the resevoir without drilling holes, (I used those nylon ties), so it can be put back to stock at anytime without any evidence that it was ever there. Just something you might want to consider to help with any overheating problems.
 

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