Question about 2001 Chevrolet Venture
1999 chevy 5.3 litre overheating. waterpump looks fine. new thermostat. what is the solution?
HI. Okay; You cant just look at a water pump and deem it functional. Its just not possible to simply look at it and say it is working. There may be serious issues that concern the internal impeller and bearing assembly. These issues can cause the impeller to freeze up, thus, not allowing for a proper flow into the block. There are two ways to check a pump to insure that it is functioning as designed. First; you can monitor the hose the is connected to the pump for flow. This hose should fell hot to the touch when the engine is at the normal operating temperature. If the hose is cold, this means that the flow is not sufficient, due to a failed pump impeller. The second test method will require the usage of a mechanics stethoscope. You can use a hose instead if you cant afford a mechanics stethoscope. Use either device to listen for bearing damage at the pump housing. A stethoscope is preferred. If you hear a rattling noise, this will confirm that the bearings are bad and the impeller is not spinning properly. The pump should be replaced, in this case.
Now; Some pumps are driven by a chain. If this is the case with your vehicle, you will need to manually check the pump by removing it and inspecting the impeller for damage. This will usually be a 5 hour job. Most pumps are external and mount onto the block and are mostly belt driven.
If you have confirmed that the pump is functional, I would advise to inspect the cooling fans and there functions(Check to see if the fans are cycling in intervals as designed. Look under the hood to visually inspect). A broken or malfunctioning cooling fan(s) can cuase the engien to run hot(overheat). Use my procedure to verify that the fans are cycling and cooling as designed.
1.Check for broken wires or loose connectors around the fan circuit. Inspect connectors at the fan motor, relay, sensor or heat sensitive switch, and the Electronic Control Module (ECM)--your car’s computer control system. Also, make sure to check for a possible blown fan fuse. These are common and overlooked troublesome spots that may cause a fan to fail.
2.Run and bring the engine to warm temperature. With the engine running, use a voltage test light to check for power to the motor fan. Be extra careful and make sure to keep your hands and tools away from the belt, fan or any other engine moving parts. If voltage is reaching the fan motor, the test light should glow.
3.Turn off the engine after you see the light glow. Apply direct voltage to the fan motor from your car battery using a pair of spare wires. If the fan fails to operate, replace the fan motor. If the motor operates, your problem is in the motor connector.
4.Locate the heat-sensitive switch or heating sensor if the fan motor operates with direct voltage and the test light did not glow. You should find the sensor in the radiator, engine block, or thermostat housing.
5.Measure the resistance across the heating sensor with the multimeter. With the engine at cool temperature (engine off), it should register infinite resistance; with the engine at warm temperature (engine off), you should read low resistance. If both readings state infinite resistance install a new heating sensor, that’s the cause of your failing fan.
6.Check the action of the fan relay if the heating sensor is registering variable resistance. Your service manual should specify the power and ground wires according to color codes and the proper way to test it. If the fan relay fails the test replace it with a new one.
7.Check the connections going to the ECM after you determine the fan relay is working properly. If you find broken wires or loose connectors, make the necessary repairs. If you suspect a defective ECM take your vehicle to a service shop for a computer analysis. In most cases, the ECM is rare to be the cause of a failing fan. The above steps should take you to the root cause of your problem and help you fix the cooler fan.
Now; If the fans are functioning, move on to the radiator.
Check the coolant level in the recovery bottle or surge tank, usually mounted on the inner fender. With the engine cold, the coolant level should be at the FULL COLD or between the FULL HOT and ADD level. With the engine at normal operating temperature, the coolant level should be at the FULL HOT or HOT mark. Only add coolant to the recovery bottle or surge tank as necessary to bring the system up to a proper level. On any vehicle that is not equipped with a coolant recovery bottle or surge tank, the level must be checked by removing the radiator cap. This should only be done when the cooling system has had time to sufficiently cool after the engine has been run. The coolant level should be within 2 in. (51mm) of the base of the radiator filler neck. If necessary, coolant can then be added directly to the radiator. While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat.
Worn caps should be replaced with a new one.Periodically clean any debris; leaves, paper, insects, etc. from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful, the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not move them again. It is recommended that the radiator be cleaned and flushed of sludge and any rust build-up once a year. If this has not been administered within the stated time, this may be why your vehicle is overheating at this time. Have the Radiator flushed asap if this is the case.
Posted on Jul 28, 2010
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Posted on Jan 02, 2017
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