Mechanics

THERMOSTAT NOT OPENING AT ALL IN COOLER WEATHER, AND HEATER NOT CONSISTENTLY PUTTING OUT HEAT.

1995 Nissan Altima • 130,000 miles

I replaced my radiator and thermostat after the old radiator cracked, but I used a Gates 180° thermostat instead of the OE 170° thermostat. Since installing it 3 days ago, I've only been able to get the thermostat to open once, when it was a sunny warmer day. Lately on cooler days (50°) the thermostat does not even open while driving uphill at high rpm (lower radiator hose stays very cool), and the engine doesn't seem to get very hot at all (the fan blows quite a bit though). Meanwhile since the thermostat isn't opening, it seems like my upper and lower radiator hoses are bulging with pressure since the coolant isn't circulating through the thermostat--can it sustain that? At the same time, I've noticed that even though the engine is warm, the heater takes awhile to put out heat, and sometimes intermittently puts out very warm heat or no heat. Could there still somehow be more air in the system causing that heater problem, or something else (vacuum?) Causing it? (I already followed the instructions using the air bleed bolt, etc to remove the air from the coolant system.)
Avatar
Erickn8318u
April 27, 2012.



The title should have said "heater NOT consistently putting out heat!"


Tiny
Erickn8318u
Apr 27, 2012.
If both your heater hoses arent getting hot and the thermostat isnt opening I would suggest replacing the thermostat with the stock oe temp one it could be a bad new one that has happened to me.I would use a stant one I have always had good luck with that brand. As far as the hoses bulging they could be weak and need replacing. As far as your heater goes are both the heater hoses going into the heater core getting really hot with the heater on?


Saturntech9
Apr 27, 2012.
After a bunch more trial runs and trying to get air out of the system (the hoses are brand new BTW, and not exactly bulging I guess), I've found that sometimes both heater hoses are hot with the heater on, and sometimes only one is hot. With the front of the car jacked up, running the vehicle shows a constant stream of bubbles gurgling into the coolant reservoir, and the car seems to maintain normal temperature fine. Could air be being pulled into the heater control valve or somewhere, causing air in the system constantly? But there doesn't seem to be any coolant leaking anywhere. I don't know why the heater problem is only intermittent. Haven't seen any fogging inside the vehicle (which would indicate leaking heater core).


Tiny
Erickn8318u
Apr 29, 2012.
Also, there is no coolant in the oil, and no sign of coolant being burned in the exhaust.


Tiny
Erickn8318u
Apr 29, 2012.
(oh, and the thermostat is opening fine, it just takes a lot of revving to heat things up enough since it's a 180-degree thermostat.)


Tiny
Erickn8318u
Apr 29, 2012.
The first thing I would do is to put the stock temp thermostat back in. Then bleed the air out of the cooling system I posted how to do that for you.


Saturntech9
Apr 29, 2012.
Thanks for the tips, I followed the instructions with the stock thermostat, but it still had constant bubbling in the coolant reservoir. A block tester kit revealed exhaust gases in the coolant. Guess it's time for a new head gasket even though there were no obvious symptoms.


Tiny
Erickn8318u
May 2, 2012.
Glad to hear you figured it out but sorry to hear the exhaust gases in the coolant. When you have the head off have the head pressure tested and make sure your valves are good also. Then have the head surfaced also straight edge your block and look for cracks. Let me kwow how it comes out.


Saturntech9
May 2, 2012.
I had a shop do the job and they had the head pressure tested and machined and said everything else was good besides the slightly failing head gasket. Seems to be running fine without the air now!


Tiny
Erickn8318u
May 4, 2012.
Glad to hear you got the car running good thats what we like to hear.


Saturntech9
May 5, 2012.