I have a 2005 sentra with the 1.8 that has 170000 miles on it. There is a weird cooling issue that I couldn't figure out and then my mechanic couldn't figure out either. While reading this, it is important to remember that this happens only half the time and the other half of the time, everything is fine. I've only noticed these symptoms since winter started but it could just be coincidence too.
Especially on cold mornings (but again not all the time) ill start driving my car and about 7-8 minutes into the drive my temperature will start to go up. If i have cruise control on during this time, my cruise will flash slowly (once a second or so) while it climbs up higher. Ive read elsewhere this is a safety feature by nissan. Before the mechanic it used to go up to just under the hot line and then it would gradually work itself back down. Then it would play this roller coaster of up and down until I shut off the car. Also during this time, my heater will try to blow out some hot air and then it eventually goes cold and stays cold. It got to a point where it started to go over the hot line and I took it to my mechanic.
Other things I've noticed are that before the mechanic my lower radiator hose would always be cold during these overheats but after the mechanic sometimes it will be warm (like it should). When it heats up real hot, my coolant reservoir fills up also and spills over. I tried burping it with no real success using the method where you stick a paper clip under the rad cap and squeeze the tubes while its running.
My mechanic had a hard time duplicating the problem but after a few days of trying he got it to heat up like it does. He bled the coolant system replaced the thermostat, filled up the coolant, changed the oil, and checked out the water pump (had some buildup on the fins but otherwise ok). He also did an exhaust test in the coolant and also did a pressurized coolant test to check for a head gasket leak and both came back ok.
I got it back from my mechanic and on the way home my temperature held good but the heater blew out cold air. So when it got home I put it in park and I revved the engine to 4000-4250 rpms for about a minute. It was continuously blowing cold air during this time but at the very end, my heat suddenly went very hot (like it should) and my lower radiator hose was hot (like it should have been) but my coolant reservoir wasn't at the top like normal. It seemed that my problem was fixed but now it's slowly working its way back to its old self. My guess is because it will overheat and fill up the coolant reservoir and I lose coolant (which puts less coolant in my system and more likely to do this).
I've read that my symptoms are similar of a head gasket leak, and even when my mechanic called the nissan dealership, they said they have seen similar cases and half the time a new head gasket will fix the problem and half the time it won't. The nissan techs didn't have a sure fire answer to help fix the problem cause they weren't sure either.
So...... After that long winding and overly descriptive problem, anyone got an idea for me? Is it possible that there's something floating around in my coolant system that only causes these problems sometimes? One constant thing that I do have is at my heater doesn't blow as hot when the car is in idle, but once I get going the heat picks back up (if I have heat that is). Could I have some water freezing some port holes in my cooling system sometimes that would cause blockages? Im pretty sure i have a good mixture of water/antifreeze. Would a faulty heater core do this?
Thanks in advance. Sorry for the novel.
Especially on cold mornings (but again not all the time) ill start driving my car and about 7-8 minutes into the drive my temperature will start to go up. If i have cruise control on during this time, my cruise will flash slowly (once a second or so) while it climbs up higher. Ive read elsewhere this is a safety feature by nissan. Before the mechanic it used to go up to just under the hot line and then it would gradually work itself back down. Then it would play this roller coaster of up and down until I shut off the car. Also during this time, my heater will try to blow out some hot air and then it eventually goes cold and stays cold. It got to a point where it started to go over the hot line and I took it to my mechanic.
Other things I've noticed are that before the mechanic my lower radiator hose would always be cold during these overheats but after the mechanic sometimes it will be warm (like it should). When it heats up real hot, my coolant reservoir fills up also and spills over. I tried burping it with no real success using the method where you stick a paper clip under the rad cap and squeeze the tubes while its running.
My mechanic had a hard time duplicating the problem but after a few days of trying he got it to heat up like it does. He bled the coolant system replaced the thermostat, filled up the coolant, changed the oil, and checked out the water pump (had some buildup on the fins but otherwise ok). He also did an exhaust test in the coolant and also did a pressurized coolant test to check for a head gasket leak and both came back ok.
I got it back from my mechanic and on the way home my temperature held good but the heater blew out cold air. So when it got home I put it in park and I revved the engine to 4000-4250 rpms for about a minute. It was continuously blowing cold air during this time but at the very end, my heat suddenly went very hot (like it should) and my lower radiator hose was hot (like it should have been) but my coolant reservoir wasn't at the top like normal. It seemed that my problem was fixed but now it's slowly working its way back to its old self. My guess is because it will overheat and fill up the coolant reservoir and I lose coolant (which puts less coolant in my system and more likely to do this).
I've read that my symptoms are similar of a head gasket leak, and even when my mechanic called the nissan dealership, they said they have seen similar cases and half the time a new head gasket will fix the problem and half the time it won't. The nissan techs didn't have a sure fire answer to help fix the problem cause they weren't sure either.
So...... After that long winding and overly descriptive problem, anyone got an idea for me? Is it possible that there's something floating around in my coolant system that only causes these problems sometimes? One constant thing that I do have is at my heater doesn't blow as hot when the car is in idle, but once I get going the heat picks back up (if I have heat that is). Could I have some water freezing some port holes in my cooling system sometimes that would cause blockages? Im pretty sure i have a good mixture of water/antifreeze. Would a faulty heater core do this?
Thanks in advance. Sorry for the novel.