Quick answer. The owner had already pulled the thermostat and the truck still overheated. Our tech found the problem in front of the radiator. The electric fans were not working, and the fan shroud was missing. With no fan pulling air and no shroud to guide it, the radiator could not shed heat. The diagnosis was one hour, $150.
Key Points
- A 1976 Chevy Cheyenne with its original radiator was running hot.
- Taking the thermostat out did not fix it.
- Our tech found the electric fans were not working.
- The fan shroud was missing, so air was not being pulled through the core.
- The diagnosis cost $150 for one hour.
Read our guides a lot? Star Supercanic as a source in Google and our new posts show up more often in your Top Stories.
What the Owner Told Us
This truck came to us running hot. It still had its original radiator.
The owner had already tried the first fix most people try. They took the thermostat out. The truck still overheated.
That tells you something. A stuck thermostat is a common cause of heat. When the thermostat is gone and the heat stays, the problem is somewhere else.
What Our Tech Found
Our tech found two things, and both were in front of the radiator.
First, the electric fans were not working. At low speed or at idle, a radiator needs a fan to pull air through it. With no fan, the coolant comes back almost as hot as it left.
Second, the fan shroud was missing. The shroud is the plastic or metal ring around the fan. It makes the fan pull air through the whole radiator, not just the middle. Without it, a lot of the air goes around the core instead of through it.
Put those two together and the truck has almost no airflow when it is not moving fast. That fits a truck that runs hot even with the thermostat out.
The Job on One Card
1976 Chevy Cheyenne, September 26
Came in with: overheating, original radiator, thermostat already removed.
Tech found: electric fans not working and the fan shroud missing.
Work done: one hour of cooling system diagnosis.
Cost: $150.
The record for this job ends at the finding. We are not going to tell you what got fixed after that, because we do not have it written down.
Why a Thermostat Is Not Always the Answer
On an old truck, people swap the cheap part first. That makes sense as a first try. But when it does not work, the next step is a test, not another part.
A radiator can be fine and still not cool. It needs air. On this truck the air was the problem. A new radiator would not have fixed dead fans or a missing shroud.
Our tech writes down what was found on the job in Shop Desk, the software our San Jacinto shop built. The owner sees the same words we do.
Frequently Asked Questions
Can I drive with the thermostat removed?
It will not cure overheating if the fans or airflow are the problem, as this truck showed. Have the cooling system tested before you drive it far.
What does a fan shroud do?
It makes the fan pull air through the whole radiator. Without it, much of the air slips around the core and the engine runs hotter.
How do I know if my electric fans work?
Let the engine warm up at idle and look at the fans. If the temperature climbs and the fans never turn on, have them tested.
How much is a cooling system diagnosis at Supercanic?
On this job it was one hour, $150. You see what the tech found before you pay for any part.
Supercanic tip: If your truck runs hot at idle but cools down on the freeway, look at the fans and the shroud first. That pattern points at airflow. Call us at (951) 904-2477.
Running Hot and Out of Guesses?
One hour of diagnosis, $150. We find the cause before you buy a part.
