Questions and Answers

Nissan Sentra Hot And Bothered Q. Dear Vincent, I recently bought a used 1991 Nissan Sentra that has been running really well. I took it for a check up at a Nissan Dealership before buying it and besides having a cracked boot and some cosmetic damage it was passed with no problems. After buying it I took it for a complete work up, had the oil and transmission fluid changed, radiator flushed and new coolant added (the previous owner had water in the coolant system).

Within a day or so of this service the car started overheating. The temperature gauge went above the "H" almost within 10 minutes of driving consistently. I also noticed some coolant dripping out, but the level in the overflow tank was normal.

Over the next few days it continued to do this. The fan was working. The coolant continued to slowly leak (only when the engine was hot). I then filled the radiator with water and just like that the problem stopped. No more overheating. I do think, however, that the car still runs a little hotter than it should. What should I do?

I can't leave the water in over winter. Do you think I have a leak? My only problem with this is that the car was overheating even with an acceptable level of coolant in the radiator. Would appreciate some advice.

1991 Nissan Sentra XE
1600cc
automatic
120,000 miles
Fuel injection

Paul...

A. Since adding the water to the cooling system seems to have brought the problem under control, I would suspect the problem is the anti-freeze.

Few people realize that pure anti-freeze will freeze. It is plain old water that is the catalyst that makes anti-freeze work. If the concentration is too high, engines will freeze and overheat.

In your case what I would do is get an anti-freeze hydrometer (don't get the ball type) and measure the protection level of the anti-freeze in the system. If it is at, for instance, -60° take out a quart or so of anti-freeze and replace it with water. Don't throw what you took out away, mix it with some water and save it for topping off. When it is about -50° you should be okay.