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Car overheating

After a trip of about an hour to the Fryeburg Fair yesterday I noticed my temperature gauge needle was going way up. I was able to park my car and went to the fair for about 4-5 hours. Before we left I checked the coolant level as the car had cooled off enough to take the cap off. The coolant right to the top and was green. I checked my oil level and that was fine. On the way home my son suggested that I turn the heat on. I did so and the temp gauge went down to normal and stayed that way all the way back home to Lewiston, Maine. I’m thinking it might be the thermostat but thought I would for any other possible reasons my car is doing this. The car has about 216,000 miles and I did have the thermostat replaced a couple of years ago…???

Could very well be a thermostat or a water pump. If you were moving when it was overheating than it is more than likely one of those 2 items.

If you were driving at sustained highway speeds and if the gauge seemed to go a little higher when you were going uphill, then I would start with a new radiator cap. You would be surprised how often this is overlooked.

With 200k on the clock and the last time the thermostat was changed was 2 years ago, you may need a good flush-n-fill. There could be crud on the radiator plugging up the cooling passages. Change the rad cap and thermostat, and you’ll be good.

If it’s been a couple of years, time to flush the cooling system, change the thermostat and add new anti freeze. Also change the radiator cap

No need to flush the cooling system, that will do more harm than good. Flushing is for brakes and toilets, not cooling systems, transmissions or induction systems.

Assuming radiator cooling fans are working per spec and spinning at correct speed. Replacing the radiator cap and thermostat and re-filling the cooling system with fresh 50/50 coolant mix are low cost and very well could fix it. Before you install it, be sure to check the new thermostat in a pan of hot water that it opens at the right temp and opens fully to the dimension spec’s by the shop manual. Might as well check the old one at the same time. It isn’t that unusual for a new thermostat to not work right out of the box. If all that didn’t fix it, I’d probably check the ignition timing, make sure it was spot on. And do a chemical test for exhaust gas in the coolant. If all that didn’t fix it, I’d take the car to my local radiator shop. If there isn’t a local radiator shop around, I’d probably just replace the radiator next.

What year and what engine?

@keith, flushing a cooling system, using older parlance, just means rinsing out with clean water, not using a pressurized flushing system, like for brakes and transmissions. If it were just coolant change, drain and fill would be Ok. With an overheating problem, coolant flow is being affected. On older cars, usually means crud build up from coolant neglect. I’ve saved a bunch of older cars like this with a good flush and fill just cleaning out the loose buildup.

BustedKnuckles, how do you know it is an older car? I don’t see a year listed in his posts. How do you know that he neglected his cooling system?

The term “flush” covers a lot of different procedures from the old pressurized flushing machines to dumping corrosive chemicals in the system to just sticking a garden hose in the radiator. Myself, I consider them all harmful. I only drain and refill, just like changing the oil. I do drain the block as well as the radiator, but I don’t put in anything other than fresh antifreeze and distilled water.

Since he has the classic symptoms of a bad radiator cap, I’d start there. If that doesn’t fix it, then I’d start looking for other causes. For example, if the upper radiator hose is cold, I’d then look at the thermostat or the water pump, if it is hot, then I’d check various spots on the radiator for cold spots. Basic troubleshooting before replacing a bunch of expensive parts.

Very few people put 216,000 miles on a car within 5 to 6 years.

Very few people put 216,000 miles on a car within 5 to 6 years.

I use to…now it takes me about 7 years. My 05 4runner has over 240k miles. I put over 300k on my 90 and 98 Pathfinders in 8 years.

A lot has to do with what part of the country you live. Here in NH…a good portion of the people drive over 30 miles each way to work. It’s not uncommon to see 150 mile round trip drives.