With the system still under pressure and the vehicle on a lift, any leakage from the radiator area should be obvious. What won’t be as obvious is a leaking water pump seal. When it comes to pump leakage, the staining evidence may be the only indication you’ll have, since it’s not unusual for the pump seals to leak inconsistently. It’s also not ­uncommon for the pump seal to show no leakage in the shop but, after the car is driven and parked, the leak is obvious. Another thing to keep in mind when looking at pump leakage is that the coolant can take some interesting paths as it works its way from the weep hole in the housing, to where it finally shows up as a drip under the engine.

Don’t overlook the possibility of leaks from the heater system, although it’s not a common problem with the Hyundai line. While the odor of the coolant, the fogged up windows or the accompanying mess generally gets the customer’s attention, don’t overlook the possibility when chasing a tough coolant hose problem.

ROAD-TESTING
So we have this Hyundai in the bay that came in with a complaint of running hot. We check the coolant level and find it to be a little low. We top it off, do a pressure test and don’t find any leaks to speak of. What is our next step? It’s time to take it on the road and see if we can duplicate the complaint. If the service writer asked the correct questions, we have some idea of when the problem occurs, but we have to take the customer’s input with a small grain of salt. While customers won’t lie about a problem, we don’t really know how attentive they are.

When I road-test an overheat problem, I like to hook up a scanner and monitor the engine coolant temp on the scanner as well as on the dash gauge. Doing this confirms that the gauge is reading properly and eliminates another question mark in the process. We’ve had more than one Hyundai with bad grounds that had the gauge showing hot, while the coolant temp was well within specs. It’s not unusual for this problem not to show up until the car is driven with the electrical system loaded.

The first step of the road-test finds us on the interstate pulling some hills to see how the system handles the high loads. We’ll also monitor the heater output at the vents, looking for air working its way back into the system, a strong indicator of a head gasket issue. Another indicator is the temp gauge going much lower; remember, the sender doesn’t read hot air, only coolant. If the temp climbs on the uphill pulls, make note of how it reacts as you return to a less-loaded condition by dropping the speed and avoiding hills.

If the temperature returns to normal, suspect a poor-flow condition caused by a plugged radiator or a thermostat that’s not opening fully. With no problem picked up on the high-speed road-test, leave the vehicle running when you return to the shop and confirm that the cooling fans are cycling as expected.

REPAIR OPTIONS
Now that we’ve topped up and bled the system and we’ve taken it on the road, it’s time to evaluate where we are and what course of action we’re going to take. If we were faced with increased temp under load, but no indication of a head gasket problem, it’s time to take another look at the radiator to decide if we’re going to recommend both a radiator and thermostat, or just the thermostat at this point. If the coolant is clean and appears to have been serviced regularly, and the cooling fins are in good shape, it pays to go with only a thermostat replacement. As always, be sure to use a quality part that’s designed for the job; Hyundais are very sensitive to coolant temperature when running the OBD II monitors for an emissions ­inspection; so don’t cause a problem while repairing ­another.

If you think you’re looking at a head gasket problem, don’t head into it lightly. While the bubbles in the funnel during the fill process, and losing heat and running hot on the highway, are solid indicators, I wouldn’t proceed without confirming the problem with a cylinder leak-down test. We won’t go into the procedure here, as it’s been covered before and can be found on www.import-car.com by searching for “head gasket.” One useful article is Cylinder Head Gasket Service Essentials.

When all is said and done, Hyundais offers no new challenges when it comes to diagnosing cooling system leaks or problems. We all should have the tools, skills and experience necessary to handle the work, and with good parts availability, there is no reason we shouldn’t welcome these cars into our bays. When it comes to service information, you can’t really ask for better. If you haven’t already, set your browser to www.hmaservice.com and register for the no-charge factory service information.