Expert: Vern Bullock - 8/18/2010

Question
QUESTION: Hi, I have a 1967 Mercury Cougar 289 v8 that will go up to the 3/4 mark or higher after a short drive around the city. I replaced the water pump, radiator, took out the thrmostat, put a new water temp sensor and rebuilt the engine. i wasnt too convinced the rebuilt engine is to perfection, but those guys insisted that these ford cars run hot naturally. the car has no leaks, what can it possibly be and how can it be fixed? or could it be the guys didnt do a good job with the rebuilt?

ANSWER: Hi Jason:
What temperature does 3/4 represent? I'm guessing it is between 190 to 210 degrees. If so, that's normal. There are two things to consider...

1. What is the temperature rating for the thermostat? Should open at around 180 - 200 degrees for a 289 engine. Make sure you have the right thermostat temperature rating for that engine.

2. Because your car is a 67, it doesn't have an electric fan to help cool the engine. I recommend you add one if you are going to do a lot of summer-time  stop and go traffic. Otherwise you should be OK.

---------- FOLLOW-UP ----------

QUESTION: thank you for your response.

I removed the thermostat. I live near the ocean, so we often have that ocean breeze and the temps around here havent been that hot. maybe adding an electric fan should be helpful, but i feel as if it should not be a necessity to have a functional classic car.

is there anything else that could be the cause of my engine heating up almost to the red danger zone? or is a faulty engine definitely the cause of my problem?

Answer
If you removed the thermostat, the engine should not run near the red zone unless it is partially clogged. Keep in mind, the thermostat is designed to quickly warm up a cold engine to prevent excess wear, so removing it is not a good idea. As long as it is opening at around 180 degrees, it is doing its job.

If the anti-freeze is circulating through the engine properly, it should keep the engine reasonably cool on normal highway driving. A good radiator/engine flush will help to remove any excess gunk that may have accumulated on the engine walls that could restrict anti-freeze flow. They can also test the compression at that time.