Engine Overheating Diagnostic Table
Step | Action | Value(s) | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
DEFINITION: Hot light on, hissing, rumble, steam, or power loss. | ||||||||||||||
1 |
Is the coolant to the proper level and the preliminary check been performed? | -- | ||||||||||||
2 |
Are there any coolant leaks? | -- | ||||||||||||
3 | Check for a loose accessory drive belt. Is the drive belt loose? | -- | ||||||||||||
4 | Repair any coolant leaks as necessary. Does the engine still overheat? | -- | System OK | |||||||||||
5 |
Are there any coolant leaks? | -- | ||||||||||||
6 | Check the condition of the drive belt. Does the engine still overheat? | -- | System OK | |||||||||||
7 | Check the condition of the radiator hoses. Are the hoses in good condition? | -- | ||||||||||||
8 | Replace the hose(s) as necessary. Refer to Radiator Hose Replacement in Engine Cooling. Does the engine still overheat? | -- | System OK | |||||||||||
9 | Check the temperature of the thermostat. Refer to Thermostat Diagnosis in Engine Cooling. Is the temperature level of the thermostat normal? | -- | ||||||||||||
10 | Replace the thermostat. Refer to Engine Coolant Thermostat Replacement in Engine Cooling. Does the engine still overheat? | -- | System OK | |||||||||||
11 | Check for a clogged radiator. Refer to Radiator Cleaning in Engine Cooling. Are the radiator coolant passages normal? | -- | ||||||||||||
12 | Inspect and clean the radiator . Does the engine still overheat? | -- | System OK | |||||||||||
13 | Check for a blockage in the engine block coolant passages. Are the engine block cooling passages normal? | -- | Flush System and Retest | |||||||||||
14 | Check if there are any combustion chamber gases leaking into the cooling system. Are there any bubbles present in the coolant? | -- | ||||||||||||
15 | Repair as necessary. Does the engine still overheat? | -- | System OK | |||||||||||
16 | Check the coolant pump for a low pumping volume. Is the pumping volume of the pump normal? | -- | ||||||||||||
17 | Replace the coolant pump. Refer to Water Pump Replacement in Engine Cooling. Does the engine still overheat? | -- | System OK | |||||||||||
18 | Check the radiator fan blade clutch. Is the fan blade clutch operating normally? | -- | ||||||||||||
19 | Replace the fan blade clutch. Refer to Fan Clutch Replacement in Engine Cooling. Does the engine still overheat? | -- | System OK | |||||||||||
20 | Other factors, such as the following, may be causing the engine to overheat:
Correct or repair as necessary. Does the engine still overheat? | -- | -- | System OK | ||||||||||
Engine Overheating Preliminary Check
- Does overheating occur while pulling a trailer?
- Is the vehicle equipped with an add-on, or aftermarket, air conditioning system? If so, was a heavy duty radiator installed?
- 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:
- If overheating occurs after prolonged driving in slow city traffic, or traffic jams, instruct the owner on the following driving techniques to avoid overheating:
| • | Does the trailer weigh less than 454 kg (1,000 lb)? |
| • | Is the vehicle equipped with a heavy duty cooling package? |
| • | 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 gauge, turn the A/C system off during extended idles of the engine. |
| • | 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 gauge, 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.
