Questions and Answers
Senta Head Gasket... Again
Q. Dear Vincent: My 1996 Nissan Sentra (70,000 miles, I bought it in January last year with 60,000 miles) blew a head gasket (and it turns out had a cracked head, though which order that came in I'll never know) last summer.
I had a reconditioned head put on the car in August. The car was doing great after that until this winter when I went on a long trip (from CT to MO) to visit family for the holidays. I put about 3,000 miles on the car total in a week's time. On the way back from the trip, the heater started fritzing out. The blower was working but sometimes it would blow cold air, and sometimes hot, no matter what the temperature was set to inside the car.
The car did not overheat at this time. It was not even slightly above normal on the gauge. I just thought the heater was broken. When I got back home, I drove it for a few days and had an appointment to have an oil change and have the heater looked at. Well, when I went to take it to the mechanic for those things, it would not start. I had it towed to the mechanic on January 8, and it has been there ever since.
They got it apart and determined that there was coolant leaking into two cylinders. It was a no brainer that the head gasket had failed again, and that something might be wrong with the head. Well, the head and the head gasket were sent to the machine shop and came back with a clean bill of health. Same goes for the block, which was tested in the garage. They cannot figure out what could have happened.
Now they have decided that they will just put the engine back together with a new head gasket anyway, and see if it will start. This makes me uneasy because I am afraid that the car will just blow another head gasket in another 10,000 miles. What could be causing this? Is there anything you can think of that would allow coolant to get in the cylinder even if the head gasket and head and block were all perfectly fine? My mechanic is stumped about this and I am very frustrated. Any help you can give me would be greatly appreciated!
Thanks so much!
JacquiA. From what I garnered from your letter, I think the failed head gasket was due to over heating, not a fault with the gasket. The fact that the heat came and went in extremes, first very cold and then very hot, indicates there was insufficient coolant in the cooling system. When they put the new head gasket on, I would have them go over the cooling system with a fine tooth comb looking for any leaks at all. Then I would have them replace the thermostat and coolant temperature sensor as well. Yeah, it's a few bucks more, but that's what you need to do to alert you to any potential problems.
Afterwards I would keep a close eye on the coolant level, not only in the reserve bottle, but in the radiator itself. I would suggest weekly checks until you are very confident there is no coolant loss.
Additional Information provided courtesy of ALLDATA
