LT1 swap into Chevelle - Cooling system problems
Thread Starter
Staging Lane
Joined: May 2008
Posts: 75
Likes: 0
From: San Francisco, CA
LT1 swap into Chevelle - Cooling system problems I'm having some problems with my cooling system. First thing is that my fans are not turning on. They turn on when the MAF is disconnected. Second is that my radiator cap starts to leak at 200 F and coolant starts to sqirt out the over flow tube onto the floor. Here is what I have and a diagram of how I have it setup. Is there something missing? Do I have to reconfigure it?
LT1
1967 Chevelle 4 Core aluminum radiator
Stock water pump
160 thermostat
LT1
1967 Chevelle 4 Core aluminum radiator
Stock water pump
160 thermostat
Sounds like air pockets.... 3 things-
1. When you disconnect some sensors (like the MAF), you should get a check eng light and the fans will turn on. Its supposed to work like that (Check engine light on= fans on).
2. The routing is almost identical to mine in my 68. The only thing I am unsure about is the heater core lines. THey are opposite of the way non LT1's are because of the reverse cooling. The only time I encountered a problem with this is when I installed the heater valve (during a vintage air install). Reversed the lines (per vintage air)and haven't had any problems since.
3. Make sure you don't have any air pockets. Is it overheating (on gauge)? Sounds like you might have an air pocket in the system. causing it to puke like that. Fill coolant/water into through the Upper radiator hose until it is full and then reconnect to the radiator (ensures the block is full with no air pockets). Take your time and do this EVERYTIME you drain your coolant. It will save you alot of headaches in the end.
What is your temp gauge reading? LT1's have 2 temp sensors. Most people use the one in the head for the temp gauge. The sensor located on the water pump (lower drivers side) is the one that PCM uses to activate the fans. Once you get the air pocket issues worked out and the fans stilll aren't working right, you might want to look at the sensor on the pump itself. Hope this helps! Let us know what you find.
1. When you disconnect some sensors (like the MAF), you should get a check eng light and the fans will turn on. Its supposed to work like that (Check engine light on= fans on).
2. The routing is almost identical to mine in my 68. The only thing I am unsure about is the heater core lines. THey are opposite of the way non LT1's are because of the reverse cooling. The only time I encountered a problem with this is when I installed the heater valve (during a vintage air install). Reversed the lines (per vintage air)and haven't had any problems since.
3. Make sure you don't have any air pockets. Is it overheating (on gauge)? Sounds like you might have an air pocket in the system. causing it to puke like that. Fill coolant/water into through the Upper radiator hose until it is full and then reconnect to the radiator (ensures the block is full with no air pockets). Take your time and do this EVERYTIME you drain your coolant. It will save you alot of headaches in the end.
What is your temp gauge reading? LT1's have 2 temp sensors. Most people use the one in the head for the temp gauge. The sensor located on the water pump (lower drivers side) is the one that PCM uses to activate the fans. Once you get the air pocket issues worked out and the fans stilll aren't working right, you might want to look at the sensor on the pump itself. Hope this helps! Let us know what you find.
Last edited by 130fe; Apr 10, 2010 at 04:50 PM.
Thread Starter
Staging Lane
Joined: May 2008
Posts: 75
Likes: 0
From: San Francisco, CA
I got my ALDL cable back from a friend and I pulled the code. It was a low coolant temp error. I had a friend move the wire around while I monitored the scan. The temp went from -20 F to 40 F to 190 F in a matter of 5 seconds. I unwraped the wiring from the loom and found broken wires. I repaired the wires and now the fans come on when they should.
The leaking radiator capis still a mystery. I talked to another car enthusiast today and he recommended i run a sealed Radiator cap and run a expasion tank with an built in over flow. That solution makes sense. Hopefully that fixes it.
The leaking radiator capis still a mystery. I talked to another car enthusiast today and he recommended i run a sealed Radiator cap and run a expasion tank with an built in over flow. That solution makes sense. Hopefully that fixes it.
