Monte Carlo SS
Cooling System FAQ
Updated April 5th, 2001
What temperature thermistat came stock in the SS (L69)?
- The stock thermistat used on the SS's L69 engine is rated at 195 degrees.
Can I use a cooler thermistat on the L69?
- Yes, you can use a 180 degree thermistat without any worry of adverse side effects and
may even see slight performance improvement based on the lower regulated temperature.
- Some use a 160 degree thermistat, but this is ill advised when used with the stock
ECM prom chip. With such a low temperature, it is possible that the ECM will not achieve
close loop operation temperature. You can get aftermarket proms which allow the use
of a 160 degree thermistat.
My engine overheats or runs hot, what could be wrong?
- Loss of coolant (See related question/answer below)
- Loss of system pressure (Pressure check)
- Low coolant protection (Test solution and add coolant as required)
- Belt tension too low (Set belt tension to spec)
- Ignition timing retarded (Set timing to specifictions)
- Timing retarded by malfunctioning ECM
- Radiator fins obstructed (Clean away bugs, leaves, etc)
- Cooling system passages (radiator, intake, cylinder heads, engine block) blocked
by rust or scale (Flush system - add fresh coolant)
- Reservoir hose pinched or kinked, especially at radiator filler neck (Relieve kinks
by re-routing. Replace hose if necessary)
- Lower radiator hose collapses (Check for hose spring position by squeezing lower end
of hose. Replace if necessary)
- Radiator air flow in wrong direction (Incorrect fan blades - replace)
- Inoperative fan clutch (Test and replace if necessary)
- Stuck or obstructed thermistat (Replace thermistat, clear obstruction)
What style water pump does the L69 engine use?
- The SS's L69 uses the long neck style small block chevy water pump.
What kind of radiator came stock on the SS?
- The stock SS radiator is a 3 core style.
On the radiator, which is the return line to the transmission?
- The top line is the return line back to the transmission.
What is the pressure rating on the stock SS radiator cap?
- 15 LB Closed System type (AC P/N RC27)
I'm loosing coolant somewhere. Where is it going?
- Leaking radiator.
- Radiator cap defective or filter neck distored.
- Leaking coolant reservoir or hose.
- Loose or damaged hoses or connections.
- Water pump seal leaking (check weep hole on bottom of pump for evidence.
Replace if necessary.)
- Water pump gasket leaking.
- Improper cylinder head bolt torque. (check oil for milky sludge for evidence)
- Cylinder head or gaskets leaking. (check oil for milky sludge for evidence)
- Cylinder block or core plug leaking. (check oil for milky sludge for evidence)
- Heater core or heater water valve leaking.
- Thermistat stuck in closed position.
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