GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Express 🢒 Engine 🢒 Engine Controls - 6.5L (L65) 🢒 Engine Overheating

Preliminary Overheating Diagnostic Inspection
  1. Does overheating occur while pulling a trailer?
    2. • Does the trailer weigh less than 454 kg (1,000 lb)?
    • Is the vehicle equipped with a heavy duty cooling package?
  2. Is the vehicle equipped with an add-on, or aftermarket, air conditioning system? If so, was a heavy duty radiator installed?
  3. If overheating occurs after prolonged idle in gear with the A/C system operating, instruct the owner on the following driving techniques to avoid overheating:
    4. • Idle the engine in N (Neutral) as much as possible. Increase the engine RPM in order to get the coolant flowing through the radiator.
    • If overheating is indicated by a hot lamp or the temperature gage, turn the A/C system off during extended idles of the engine.
  4. If overheating occurs after prolonged driving in slow city traffic, or traffic jams, instruct the owner on the following driving techniques to avoid overheating:
    5. • Idle the engine in N (Neutral) as much as possible. Increase the engine RPM in order to get the coolant flowing through the radiator.
    • If overheating is indicated by a hot lamp or the temperature gage, turn the A/C system off during extended idles of the engine.

If any of the above conditions apply, instruct the operator on driving techniques that would reduce the possibility of engine overheating.

Step

Action

Yes

No

DEFINITION: Hot light on, hissing, rumble, steam, or power loss.

1
  1. Perform the preliminary inspection.
  2. Inspect the coolant level in the coolant recovery reservoir or surge tank.

Is the coolant to the proper level and the preliminary inspection been performed?

Go to Step 3

Go to Step 2

2
  1. Add the proper coolant. Refer to

    Notice: When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

    in Cautions and Notices.
  2. Inspect for visual coolant leaks.

Are there any coolant leaks?

Go to Step 4

Go to Step 5

3

Inspect for a loose accessory drive belt.

Is the drive belt loose?

Go to Step 6

Go to Step 7

4

Repair any coolant leaks as necessary.

Does the engine still overheat?

Go to Step 3

System OK

5
  1. Pressure test the cooling system.
  2. Inspect for coolant leaks.

Are there any coolant leaks?

Go to Step 4

Go to Step 3

6

Inspect the condition of the drive belt.

Does the engine still overheat?

Go to Step 7

System OK

7

Inspect the condition of the radiator hoses.

Are the hoses in good condition?

Go to Step 9

Go to Step 8

8

Replace the hose(s) as necessary. Refer to Radiator Inlet Hose Replacement and Radiator Outlet Hose Replacement .

Does the engine still overheat?

Go to Step 9

System OK

9

Inspect the temperature of the thermostat. Refer to Thermostat Diagnosis .

Is the temperature level of the thermostat normal?

Go to Step 11

Go to Step 10

10

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Does the engine still overheat?

Go to Step 11

System OK

11

Inspect for a clogged radiator. Refer to Radiator Cleaning .

Are the radiator coolant passages normal?

Go to Step 13

Go to Step 12

12

Inspect and clean the radiator.

Does the engine still overheat?

Go to Step 13

System OK

13

Inspect for a blockage in the engine block coolant passages.

Are the engine block cooling passages normal?

Go to Step 14

Go to Flushing

14

Inspect if there are any combustion chamber gases leaking into the cooling system.

Are there any bubbles present in the coolant?

Go to Step 15

Go to Step 16

15

Repair as necessary.

Does the engine still overheat?

Go to Step 16

System OK

16

Inspect the water pump for a low pumping volume.

Is the pumping volume of the pump normal?

Go to Step 18

Go to Step 17

17

Replace the water pump. Refer to Water Pump Replacement .

Does the engine still overheat?

Go to Step 18

System OK

18

Inspect the radiator fan clutch.

Is the fan clutch operating normally?

Go to Step 20

Go to Step 19

19

Replace the fan clutch. Refer to Fan Clutch Replacement .

Does the engine still overheat?

Go to Step 20

System OK

20

Other factors, such as the following, may be causing the engine to overheat:

    • A heavy vehicle payload
    • The A/C system
    • Excess engine oil
    • Restricted air flow through the radiator
        Refer to Radiator Cleaning .

Correct or repair as necessary.

Does the engine still overheat?

--

System OK