Overheating has several possible causes and only one of them is the thermostat, so replacing parts in order is an expensive way to find the answer. AutoTech Clinic tests the cooling system properly at our Dearborn shop: pressure test, fan operation, flow, live temperature data and a block test for combustion gases.
Time matters here. An engine that runs hot for a few minutes can warp a cylinder head, and that turns a cheap repair into a large one. If your gauge is climbing, stop driving and call (313) 277-7200.
- How Long
- About 1 to 2 hours of diagnostic time.
- Same Day
- Usually finished the same day.
- Vehicles
- Foreign and domestic, cars through trucks.
Signs You Need Overheating Diagnostics
- The temperature gauge above its usual position or in the red
- A high temperature warning light or message
- Steam or a sweet smell from under the hood
- The engine losing power or the computer putting it in a protection mode
- Coolant overflowing from the reservoir after you park
- Overheating only in traffic, or only on the highway, which points in different directions
What We Do
- 01
Pressure Test Cold
We pressurize the system cold and look for external leaks, a failed cap and pressure that will not hold.
- 02
Verify Fan Operation
We confirm the cooling fan runs when it should, at the right speeds, and check the relay, control module and temperature sensor.
- 03
Check Flow and Blockage
We use a temperature gun across the radiator face to find cold spots that show internal blockage, and confirm the water pump is moving coolant.
- 04
Watch Live Data
We monitor coolant temperature through a full warm up cycle to see exactly where and when the problem starts.
- 05
Block Test for Combustion Gases
If nothing else explains it, we test for combustion gases in the coolant, which confirms or rules out a head gasket.
When It Overheats Tells Us Where to Look
Overheating only in traffic and cooling down on the highway almost always means airflow: a cooling fan that is not running, a failed relay or a blocked condenser and radiator face. Air moves through the radiator naturally at speed, so the fault hides.
Overheating on the highway but not in traffic points the other way, toward flow: a weak water pump, a restricted radiator or a thermostat that is not opening fully. Tell us when it happens and you have narrowed the diagnosis before we start.
What to Do When the Gauge Climbs
Turn the air conditioning off and the heater to full hot with the fan on high. That uses the heater core as a second radiator and can buy you a few minutes. Pull over somewhere safe and shut the engine off.
Do not open the radiator cap on a hot engine. The system is pressurized and the coolant is well above boiling, and it will come out violently. Let it cool completely, then check the reservoir level.
What Affects the Cost
We quote your vehicle specifically after inspecting it, because these are the things that move the number up or down:
- How many tests are needed to isolate the cause
- Whether the fault is intermittent and only appears in traffic or under load
- The repair itself, which ranges from a cap to a head gasket
- Whether the overheat has already damaged the head gasket or the head
- Access to the part that failed
Call (313) 277-7200 with your year, make and model and we will tell you what to expect before you come in.
Why AutoTech Clinic
AAA Approved
An inspected facility that has to meet AAA standards for equipment and training.
Photos First
You see what we found and approve the price before anything is taken apart.
Same-Day Service
Parts on hand for the vehicles we see most, so you are not waiting on a delivery.