Hi, new member.
2007 Commander, 3.7, 2wd.
Not a bad vehicle, but always fixing something on it, looking for help for the weird ones
The big issue is cooling. Over the last couple months, I've replaced the thermostat, the thermostat gasket twice, the thermostat housing, the water pump, and the upper radiator hose.
Things go well for a couple weeks, then it starts overheating again at stoplights. It's also not pulling any coolant from the overflow tank, it just loses water, about a couple cups every few weeks
When the engine is cool, like overnight, I slowly open the radiator cap, and it seems pressurized, like a bottle of soda. If I hold down on the cap after twisting and just barely lift it up, it bubbles cool air up into the overflow tank.
I've taken the overflow coolant hose off the radiator nipple (when cold), and coolant pours nicely out of the tank. I've poked through the nipple to the radiator with a long piece of wire to see if there's blockage, but it goes through fine. With the radiator cap off, I can see coolant leaking slowly into the radiator from the overflow tank, but apparently it's not happening with the cap on.
I was worried about the head gasket, but I've replaced the coolant several times (changing the thermo housing, etc) and no trace of oil, and I replaced the oil recently and no trace of water. No steam coming out of the exhaust pipe.
I can't see where any coolant is leaking. Before I replaced the upper hose, there was a crack I could see bubbling when hot, but now the hose is new and looks fine. Before I replaced the water pump, I could see a small leak near the bottom, but not since I replaced it.
Even when it's overheating, I don't see or hear any steam or hissing from anywhere, the radiator, the hoses, anything.
Is it normal to have a pressurized radiator when the engine is cool? Shouldn't it be more of a vacuum, sucking in extra coolant from the overflow tank?
Any ideas what to look at next?
Welcome to the forum;
Cooling issues are not uncommon with Commanders and it doesn't seem relegated to any one particular power-train either.
Maybe this list will help give you some ideas;
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the complaint. Abnormal loads on the cooling system such as the following may be the cause:
Very high ambient temperature
Slight tail wind at idle
Any accessory addition that fully or partially blocks the grille opening
Driving techniques that avoid overheating are:
Idle with A/C off when temperature gauge is at end of normal range.
Increase engine speed for more air flow is recommended.
1. TRAILER TOWING:
Consult Trailer Towing section of owners manual. Do not exceed limits.
2. RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been performed on vehicle that may effect cooling system. This may be:
Engine adjustments (incorrect timing)
Slipping engine accessory drive belt(s)
Brakes (possibly dragging)
Changed parts. Incorrect water pump, or pump rotating in wrong direction due to belt not correctly routed
Reconditioned radiator or cooling system refilling (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous items as a cause for an engine overheating complaint, refer to following Cooling System Diagnosis charts.
These charts are to be used as a quick-reference only. Refer to the group text for information.
COOLING SYSTEM DIAGNOSIS CHART CONDITION
TEMPERATURE GAUGE READS LOW
1. Has a Diagnostic Trouble Code (DTC) been set indicating a stuck open thermostat?
1. Refer to (Refer to 25 - EMISSIONS CONTROL - DESCRIPTION) for On-Board Diagnostics and DTC information. Replace thermostat if necessary.
2. Is the temperature sending unit connected?
2. Check the temperature sensor connector. (Refer to 7 - COOLING/ENGINE/ENGINE COOLANT TEMP SENSOR - DESCRIPTION). Repair connector if necessary.
3. Is the temperature gauge operating OK?
3. Check gauge operation. Repair as necessary.
4. Coolant level low in cold ambient temperatures accompanied with poor heater performance.
4. Check coolant level in the coolant reserve/overflow tank and the radiator. Inspect system for leaks. Repair leaks as necessary.
5. Improper operation of internal heater doors or heater controls.
5. Inspect heater and repair as necessary. (Refer to 24 - HEATING & AIR CONDITIONING - DIAGNOSIS AND TESTING)
TEMPERATURE GAUGE READS HIGH OR THE COOLANT LAMP ILLUMINATES. COOLANT MAY OR MAY NOT BE LOST OR LEAKING FROM THE COOLING SYSTEM
1. Trailer is being towed, a steep hill is being climbed, vehicle is operated in slow moving traffic, or engine is being idled with very high ambient (outside) temperatures and the air conditioning is on. Higher altitudes could aggravate these conditions.
1. This may be a temporary condition and repair is not necessary. Turn off the air conditioning and attempt to drive the vehicle without any of the previous conditions. Observe the temperature gauge. The gauge should return to the normal range. If the gauge does not return to the normal range, determine the cause for overheating and repair.
2. Is the temperature gauge reading correctly?
2. Check gauge. (Refer to Group 8J - INSTRUMENT CLUSTER). Repair as necessary.
3. Is the temperature warning illuminating unnecessarily?
3. Check warning lamp operation. (Refer to Group 8J - INSTRUMENT CLUSTER). Repair as necessary.
4. Coolant low in coolant reserve/overflow tank and radiator?
4. Check for coolant leaks and repair as necessary. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING).
5. Pressure cap not installed tightly. If cap is loose, boiling point of coolant will be lowered. Also refer to the following Step 6.
5. Tighten cap
6. Poor seals at the radiator cap.
6. (a) Check condition of cap and cap seals. (Refer to 7 - COOLING/ENGINE/RADIATOR PRESSURE CAP - DIAGNOSIS AND TESTING).
(b) Check condition of radiator filler neck. If neck is bent or damaged, replace radiator.
7. Coolant level low in radiator but not in coolant reserve/overflow tank. This means the radiator is not drawing coolant from the coolant reserve/overflow tank as the engine cools
7. (a) Check condition of radiator cap and cap seals. (Refer to 7 - COOLING/ENGINE/RADIATOR PRESSURE CAP - DIAGNOSIS AND TESTING).
(b) Check condition of radiator filler neck. If neck is bent or damaged, replace radiator.
(c) Check condition of the hose from the radiator to the coolant tank. It should fit tight at both ends without any kinks or tears. Replace hose if necessary.
(d) Check coolant reserve/overflow tank and tanks hoses for blockage. Repair as necessary.
8. Incorrect coolant concentration
8. Check coolant. (Refer to 7 - COOLING/ENGINE/COOLANT - DESCRIPTION) for correct coolant/water mixture ratio.
9. Coolant not flowing through system
9. Check for coolant flow at radiator filler neck with some coolant removed, engine warm and thermostat open. Coolant should be observed flowing through radiator. If flow is not observed, determine area of obstruction and repair as necessary.
10. Radiator or A/C condenser fins are dirty or clogged.
10. Remove insects and debris. (Refer to 7 - COOLING/ENGINE/RADIATOR - CLEANING).
11. Radiator core is corroded or plugged.
11. Have radiator re-cored or replaced.
12. Aftermarket A/C installed without proper radiator.
12. Install proper radiator.
13. Fuel or ignition system problems.
13. Refer to FUEL and /or IGNITION CONTROL for diagnosis.
14. Dragging brakes.
14. Check and correct as necessary. (Refer to 5 - BRAKES - DIAGNOSIS AND TESTING) for correct procedures.
15. Bug screen or cardboard is being used, reducing airflow.
15. Remove bug screen or cardboard.
16. Thermostat partially or completely shut.
16. Check thermostat operation and replaces necessary. (Refer to 7 - COOLING/ENGINE/ENGINE COOLANT THERMOSTAT - DIAGNOSIS AND TESTING).
17. Viscous fan drive not operating properly.
17. Check fan drive operation and replace as necessary. (Refer to 7 - COOLING/ENGINE/FAN DRIVE VISCOUS CLUTCH - DIAGNOSIS AND TESTING).
18. Cylinder head gasket leaking.
18. Check for cylinder head gasket leaks. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING). For repair, (Refer to 9 - ENGINE/CYLINDER HEAD - REMOVAL).
19. Heater core leaking.
19. Check heater core for leaks. (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/HEATER CORE - REMOVAL). Repair as necessary.
20. Hydraulic fan speed too low or inoperative.
20. Check for DTC code.
Check fan operation speeds.
Refer to fan speed operation table.
Low power steering pump output. Refer to power steering pump diagnosis - 4.7L engine.
TEMPERATURE GAUGE READING IS INCONSISTENT (FLUCTUATES, CYCLES OR IS ERRATIC)
1. During cold weather operation, with the heater blower in the high position, the gauge reading may drop slightly.
1. A normal condition. No correction is necessary.
2. Temperature gauge or engine mounted gauge sensor defective or shorted. Also, corroded or loose wiring in this circuit.
2. Check operation of gauge and repair if necessary. Refer to Group 8J, Instrument cluster.
3. Gauge reading rises when vehicle is brought to a stop after heavy use (engine still running)
3. A normal condition. No correction is necessary. Gauge should return to normal range after vehicle is driven.
4. Gauge reading high after re-starting a warmed up (hot) engine.
4. A normal condition. No correction is necessary. The gauge should return to normal range after a few minutes of engine operation.
5. Coolant level low in radiator (air will build up in the cooling system causing the thermostat to open late).
5. Check and correct coolant leaks. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING).
6. Cylinder head gasket leaking allowing exhaust gas to enter cooling system causing a thermostat to open late.
6. (a) Check for cylinder head gasket leaks. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING).
(b) Check for coolant in the engine oil. Inspect for white steam emitting from the exhaust system. Repair as necessary.
7. Water pump impeller loose on shaft.
7. Check water pump and replace as necessary. (Refer to 7 - COOLING/ENGINE/WATER PUMP - DIAGNOSIS AND TESTING) .
8. Loose accessory drive belt. (water pump slipping)
8. (Refer to 7 - COOLING/ACCESSORY DRIVE/DRIVE BELTS - DIAGNOSIS AND TESTING) . Check and correct as necessary.
9. Air leak on the suction side of the water pump allows air to build up in cooling system causing thermostat to open late.
9. Locate leak and repair as necessary.
PRESSURE CAP IS BLOWING OFF STEAM AND/OR COOLANT TO COOLANT TANK. TEMPERATURE GAUGE READING MAY BE ABOVE NORMAL BUT NOT HIGH. COOLANT LEVEL MAY BE HIGH IN COOLANT RESERVE/OVERFLOW TANK
1. Pressure relief valve in radiator cap is defective.
1. Check condition of radiator cap and cap seals. (Refer to 7 - COOLING/ENGINE/RADIATOR PRESSURE CAP - DIAGNOSIS AND TESTING). Replace cap as necessary.
COOLANT LOSS TO THE GROUND WITHOUT PRESSURE CAP BLOWOFF. GAUGE READING HIGH OR HOT
1. Coolant leaks in radiator, cooling system hoses, water pump or engine.
1. Pressure test and repair as necessary. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING).
DETONATION OR PRE-IGNITION (NOT CAUSED BY IGNITION SYSTEM). GAUGE MAY OR MAY NOT BE READING HIGH
1. Engine overheating.
1. Check reason for overheating and repair as necessary.
2. Freeze point of coolant not correct. Mixture is too rich or too lean.
2. Check coolant concentration. (Refer to 7 - COOLING/ENGINE/COOLANT - DESCRIPTION) and adjust ratio as required.
HOSE OR HOSES COLLAPSE WHILE ENGINE IS RUNNING
1. Vacuum created in cooling system on engine cool-down is not being relieved through coolant reserve/overflow system.
1. (a) Radiator cap relief valve stuck. (Refer to 7 - COOLING/ENGINE/RADIATOR PRESSURE CAP - DIAGNOSIS AND TESTING). Replace if necessary
(b) Hose between coolant reserve/overflow tank and radiator is kinked. Repair as necessary.
(c) Vent at coolant reserve/overflow tank is plugged. Clean vent and repair as necessary.
(d) Reserve/overflow tank is internally blocked or plugged. Check for blockage and repair as necessary.
NOISY VISCOUS FAN/DRIVE
1. Fan blades loose - 4.7L.
1. Replace fan blade assembly. (Refer to 7 - COOLING/ENGINE/RADIATOR FAN - REMOVAL)
2. Fan blades striking a surrounding object.
2. Locate point of fan blade contact and repair as necessary.
3. Air obstructions at radiator or air conditioning condenser.
3. Remove obstructions and/or clean debris or insects from radiator or A/C condenser.
4. Thermal viscous fan drive has defective bearing - 4.7L
4. Replace fan drive. Bearing is not serviceable. (Refer to 7 - COOLING/ENGINE/RADIATOR FAN - REMOVAL).
INADEQUATE HEATER PERFORMANCE.
1.Thermostat failed in open position
1. Check thermostat operation and replaces necessary (Refer to 7 - COOLING/ENGINE/ENGINE COOLANT THERMOSTAT - DIAGNOSIS AND TESTING)
2. Has a Diagnostic trouble Code (DTC) been set?
2. (Refer to 25 - EMISSIONS CONTROL - DESCRIPTION) for correct procedures and replace thermostat if necessary
3. Coolant level low
3. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING).
4. Obstructions in heater hose/fittings
4. Remove heater hoses at both ends and check for obstructions
5. Heater hose kinked
5. Locate kinked area and repair as necessary
6. Water pump is not pumping water to/through the heater core. When the engine is fully warmed up, both heater hoses should be hot to the touch. If only one of the hoses is hot, the water pump may not be operating correctly or the heater core may be plugged. Accessory drive belt may be slipping causing poor water pump operation.
6. (Refer to 7 - COOLING/ENGINE/WATER PUMP - DIAGNOSIS AND TESTING). If a slipping belt is detected, (Refer to 7 - COOLING/ACCESSORY DRIVE/DRIVE BELTS - REMOVAL). If heater core obstruction is detected, (Refer to 7 - COOLING - STANDARD PROCEDURE) for cooling system reverse flushing.
STEAM IS COMING FROM THE FRONT OF VEHICLE NEAR THE GRILL AREA WHEN WEATHER IS WET, ENGINE IS WARMED UP AND RUNNING, AND VEHICLE IS STATIONARY. TEMPERATURE GAUGE IS IN NORMAL RANGE
1. During wet weather, moisture (snow, ice or rain condensation) on the radiator will evaporate when the thermostat opens. This opening allows heated water into the radiator. When the moisture contacts the hot radiator, steam may be emitted. This usually occurs in cold weather with no fan or airflow to blow it away.
1. Occasional steam emitting from this area is normal. No repair is necessary.
1. Coolant color is not necessarily an indication of adequate corrosion or temperature protection. Do not rely on coolant color for determining condition of coolant.
1. (Refer to 7 - COOLING/ENGINE/COOLANT - DESCRIPTION) for coolant concentration information. Adjust coolant mixture as necessary.
COOLANT LEVEL CHANGES IN COOLANT RESERVE/OVERFLOW TANK. TEMPERATURE GAUGE IS IN NORMAL RANGE
1. Level changes are to be expected as coolant volume fluctuates with engine temperature. If the level in the tank was between the FULL and ADD marks at normal operating temperature, the level should return to within that range after operation at elevated temperatures.
1. A normal condition. No repair is necessary.
FAN RUNS ALL THE TIME
1. Fan control sensors inoperative.
1. Check for DTC's. Verify sensor readings.
2. Fan control solenoid stuck "on".
2. Check fan operation speeds. Refer to fan speed operation table.
3. Fan control solenoid harness damaged.
3. Check for DTC 1499. Repair as required.
4. Transmission temperature too high.
4. Check for transmission over temp. DTC.
5. Engine coolant temperature too high.
5. (a) Check coolant level. Correct level as required.
(b) Thermostat stuck. Replace thermostat.
(c) Water pump failed. Replace water pump.
(d) Coolant flow restricted. Clean radiator.
(e) Air flow over radiator obstructed. Remove obstruction.
The cooling system regulates engine operating temperature. It allows the engine to reach normal operating temperature as quickly as possible, maintains normal operating temperature and prevents overheating.
The cooling system also provides a means of heating the passenger compartment. The cooling system is pressurized and uses a centrifugal water pump to circulate coolant throughout the system. A separate and remotely mounted, pressurized coolant tank using a pressure/vent cap is used.
COOLING SYSTEM COMPONENTS
The cooling system consists of:
Charge Air Cooler (Turbocharger only)
Hydraulic Cooling Fan - Diesel only
Electric cooling fan - 3.7L
Electric cooling fan and mechanical thermal viscous fan - 4.7L only
A separate pressurized coolant bottle 3.7L/4.7L/3.0L
A non-pressurized coolant recovery system - 5.7L
Transmission oil cooler (if equipped with an automatic)
Radiator pressure cap
Power Steering Cooler - 3.7L/4.7L/3.0L
Hoses and hose clamps
The radiator cooling fan used on the 4.7L engine is a hybrid design. The hybrid fan system consist of a low speed viscous driven mechanical fan and a electrical fan.
WARNING: DO NOT ATTEMPT TO BEND OR STRAIGHTEN FAN BLADES IF FAN IS NOT WITHIN SPECIFICATIONS.
CAUTION: If fan blade assembly is replaced because of mechanical damage, water pump and viscous fan drive should also be inspected. These components could have been damaged due to excessive vibration.
1. Remove fan blade assembly from viscous fan drive unit (four bolts).
2. Lay fan on a flat surface with leading edge facing down. With tip of blade touching flat surface, replace fan if clearance between opposite blade and surface is greater than 2.0 mm (.090 inch). Rocking motion of opposite blades should not exceed 2.0 mm (.090 inch). Test all blades in this manner.
3. Inspect fan assembly for cracks, bends, loose rivets or broken welds. Replace fan if any damage is found.
CAUTION: Do not operate an engine without a thermostat, except for servicing or testing.
A pellet-type thermostat controls the operating temperature of the engine by controlling the amount of coolant flow to the radiator. On all engines the thermostat is closed below 195°F (90°C). Above this temperature, coolant is allowed to flow to the radiator. This provides quick engine warm up and overall temperature control.
The same thermostat is used for winter and summer seasons. An engine should not be operated without a thermostat, except for servicing or testing. Operating without a thermostat causes other problems. These are: longer engine warmup time, unreliable warmup performance, increased exhaust emissions and crankcase condensation. This condensation can result in sludge formation.
DIAGNOSIS AND TESTING - THERMOSTAT
All models are equipped with On-Board Diagnostics for certain cooling system components. If the powertrain control module (PCM) detects low engine coolant temperature, it will record a Diagnostic Trouble Code (DTC).