A portable emissions analyzer from EMS can be used to test for head gasket leaks. Head gasket leaks can be checked this way on any vehicle. For more information on this product please check out vehicleservicepros.com/10097468
Photo credit: EMS
Using the ATS EScan we can monitor how long it takes this thermostat to open. If it opens too slowly, like it is doing here, the proper repair is to replace the thermostat. For more information on this product check out vehicleservicepros.com/10106486
Photo credit: Craig Truglia
The Snap-on SVTS262C can be used not only to do a pressure test but also to check for bad head gaskets. This can be done by attaching the pump from the SVTS262C to the cooling system using the included TAB10036 adapter. Once attached, start the engine and rev it up a bit while watching the gauge on the pump for pressure spikes that would indicate an exhaust leak into the cooling system. If there is an exhaust leak, then you must have a head gasket leak. For more information on this product check out vehicleservicepros.com/10892025
Photo credit: Snap-on
Here a radiator fan is jumped using the Power Probe Hook and a lead set. The tool not only allows the user to verify that the fan works, it measures the fan amperage draw simultaneously. For more information on this tool check out vehicleservicepros.com/10727921
Photo credit: Power Probe
Matco recommends coupling its TP3405 leak detection dye with its RPT102 Cooling System Pressure Tester. When under pressure, dye may be left behind where a black light can be used to spot tough to find leaks. For more information visit vehicleservicepros.com/10892027
Photo credit: Matco
The Matco RPT102 Cooling System Pressure Tester is being used after topping off the antifreeze. Matco recommends coupling its TP3405 leak detection dye with its RPT102 Cooling System Pressure Tester. When under pressure, dye may be left behind where a black light can be used to spot tough to find leaks. For more information visit vehicleservicepros.com/10892027
Photo credit: Matco
Any pressure tester worth its salt, such as Astro Pneumatic's Radiator Pressure Tester No. 78585 here, will have the right adapters to connect to vehicles that have pressurized caps on their coolant overflow reservoirs. For more information on this product check out vehicleservicepros.com/10166850
Photo credit: Astro Pneumatic
A scan tool's bidirectional controls are a quick way to confirm that the PCM, wiring and fan are all in good working order. For more information on this product check out vehicleservicepros.com/10849873
Photo credit: Launch
The Ansed gas analyzer test for HC gas in a cooling system overflow/filler tank. For information on this product, go to www.VehicleServicePros.com/10697838.
The Hickok/Waekon cooling system test and refill kit No. 61868 uses air to maintain constant pressure without the engine running. For information on this product, go to www.VehicleServicePros.com/10772739.
The MV4530 cooling system pressure test kit from Mityvac includes a high-pressure pump and four adapters for connecting to the cooling system of most U.S. and Asian cars and light trucks. For more information about this product, go to www.VehicleServicePros.com/10890606
By adding a few drops of coolant to the test surface and pressing the "Go" button a couple seconds later the RTI VFT-1 will give a digital readout of the freezing point. For information on this product, go to www.VehicleServicePros.com/10890621
RTI's MCX-2 (Multi Coolant Exchanger) can be connected in line with the vehicle's cooling system through the upper radiator hose or in situations when that is not ideal on some vehicles with a pressurized reservoir. For information on this product, go to www.VehicleServicePros.com/10125763.
Photo credit: RTI
There are quite a few vehicles out there that have common cooling system problems. BMW 3 Series always have fan clutches and thermostats going bad. Volkswagens have bad water pumps. Late model Jeep I6s have head gasket issues. The list goes on and on.
Now a 2006 Chevy Equinox with a 3.4L comes in with the issue of overheating and the “antifreeze boils.” The boiling of antifreeze indicates that something critical is defective (clogged radiator, defective thermostat, broken water pump impeller, etc.) Since 3.4Ls don’t typically have this issue, what would be the wise way to begin diagnosing this car?
1) Check anti-freeze
This step is absolutely critical, because if the antifreeze is full, we will probably test the thermostat first and if it is low, we will pressure test the vehicle for leaks. So, to check for a leak we top the vehicle off with antifreeze and attach the pressure tester where the radiator cap is. Some vehicles don’t have radiator caps, but they have pressurized overflow containers where the pressure tester connects to.
Regardless of where you connect to, you should be able to tighten the tester’s adapter so that it makes a leak-proof seal and pressurizes the system to 15 psi. That system should hold at least 15 psi for five minutes. If not, look for leaks. Any component that is visibly leaking should be replaced. But what if you don’t see any leaks and you are losing pressure?
2) Test for bad head gasket
The old fashioned way to test for a bad head gasket is to pressure test the vehicle, and if you find a leak but don’t see any, check the exhaust. If it smells and looks like burned antifreeze, you have a head gasket leak on your hands.
However, for reasons we covered in our December 2012 Tool Q&A (Go to VehicleServicePros.com/10765228 to read that article), catalytic converters work too efficiently these days and only with extremely bad head gasket leaks will you catch it that way. Otherwise, the only way to be sure we are not getting any antifreeze in the oil is to use an emissions analyzer.
Simply turn on your emissions analyzer and check the HC levels in the shop. The number should be close to zero. Then, open the radiator cap. If you are afraid of a coolant bubble shooting out and getting into your probe, use a no-spill antifreeze funnel and half a windshield washer bottle. In the hole on the top, put your probe. When you do this, see if HC levels soar.
If they do, you have confirmed that the head gasket is bad, because HC from the combustion chamber of the engine is now getting into the antifreeze. This, in turn, confirms that antifreeze is going into the combustion chamber and out the tail pipe.
3) Test for items that cause overheating
What if we have this problem and the antifreeze level is not low? The first component we test is the thermostat.
To test a thermostat, first make sure that the vehicle is cold and the thermostat is closed. As the vehicle warms up, feel the thermostat hose. At the same time, use a scan tool and graph the engine coolant temperature (ECT) PID. When ECT reaches the range where the thermostat is rated to open, feel the thermostat hose. The hose should turn from cool to hot.
If the ECT PID goes up very slowly, for example, an increase of only 10 degrees F every few minutes, then you likely have a “sticky” thermostat. The EScan from Automotive Test Solutions is a scan tool with a thermostat testing function which automatically calculates this for you, so you don’t have to touch any hoses or perform any “guesstimations.”
If the thermostat is good and you notice that even when the vehicle is hot the radiator fan won’t turn on, you might want to test the radiator fan. You can do this by using a bi-directional control on our scan tool, or lacking that, jump the radiator fan on with a Power Probe.
Using your scan tool to do the test is easy. Simply go into the engine control module and choose bi-directional controls. “Radiator fan” should be an available choice. If the fan does not engage, your scan tool might list bi-directional control but not actually do it, or more likely, the PCM driver, fan or its wiring is defective.
The quick way to test this out is to simply whip out a Power Probe. You will need to take into account the wiring of the vehicle (i.e., is the fan grounded/powered seperately from the PCM?). Depending upon how the fan is wired you can check to see if the fan is receiving 12V and even jump the circuit. In this way, you can prove if the fan alone is bad or if the PCM or wiring is at fault.
Most fans are grounded by the PCM, so with the Power Probe you can bypass that ground and make your own. If the fan spins, you have a problem on the ground side. Sometimes, the fans blow fuses when they have high internal resistance. You can check amperage on the fan with an amp clamp or a Power Probe Hook when performing this test. If fan amperage is too “close” to the fuse’s amperage rating, the radiator fan should be replaced.
If you see a good degree of “Dex Mud” in the radiator, you might have a blockage. To diagnose a clogged radiator, the simple way is to pull its hoses, let whatever residual antifreeze there is drain out and then blow shop air through the radiator. If you cannot successfully flush out the radiator, replace it.
One of the rarer problems is a defective water pump impeller. A simple way to catch this issue is to pull a hose where the water pump is and see what kind of force the pump shoots the antifreeze out at. If you are confused about which hoses are at the inlet and outlet sides, get some clear plastic hose at a home improvement store and put those in place of the other hoses. Then, turn the car on to monitor coolant flow. This trick can be used to monitor flow in and out of the heater core as well.
Lastly, thermal imaging can assist in doing many of the preceding diagnostics. It can quickly discern the temperature of antifreeze at different points of the cooling system. The most advanced thermal imagers can look into a radiator and see where the flow of hot antifreeze stops. However, sometimes there are so many hot parts on a vehicle surrounded by other hot parts, it’s not possible to get that precise. But, an array of diagnostic equipment can help the technician nail any cooling system issue.