Altima thermostat, stuck open?

Just looking for an opinion or two here; I have a 99 Altima that's always seemed to take a long time to warm up, particularly in the winter. It's an unusually cold night here (2-3 deg C) and I just went for a 40 minute drive. Mostly 60km/h and up, and not much stop & go. When I shut the car off, the lower rad hose (between the thermostat and the rad) was not by any means hot, lukewarm at best, while the upper hose was quite warm, but not scorchingly so.

The temp gauge was up to the normal range, and the car had been running a few hours previous to when I started, so shouldn't the thermostat be fully open and the coolant nice and warm? Or is the rad just doing a very good job of cooling the coolant in this weather?

Reply to
JM
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Replace the thermostat. How old is it?

Reply to
Hugo Schmeisser

It's original... are you saying a 7 year old thermostat might be bad?? :) Seriously though, I think I'll price one tomorrow or at least pull mine and see if it's open.

Reply to
JM

I say yes. And with no smiley either.

It will be closed when you pull it out, and it will tell you nothing.

Are you so parsimonious that you begrudge spending money on a $25 thermostat? Doesn't your engine cost more than $25? I'll bet your coolant is original as well.

Reply to
Hugo Schmeisser

Hey, all I asked for was a simple opinion from anyone more experienced than myself. It's not a matter of the money involved but more of a matter of trying not to waste a lot of time and effort replacing parts that are perfectly good. Whether I replace it or not is my decision and none of your concern, and if I don't, and my engine explodes tomorrow, that's something only I have to live with. As for the coolant it's new this fall.. I probably maintain my car better than 90% of the population.

Reply to
JM

You didn't supply a lot of really good info. You said your car has a temp gauge. You said it gets to the normal range. Does that mean it go just as high when its cold outside as when it is warm? If it does your cooling system is working and the thermostat is restricting the flow to keep the temp up where it should be. You said it takes a long time to warm up. Is that opinion based on what you see the temp gauge do or is it based on your feel the radiator hose test? How long does it take to get heat from the heater. It is possible that the thermostat isn't closing all the way when its cold. But if your concern is that it takes a long time for the radiator hoses to get warm

- that's the way its supposed to work. You probably have the heater on and that's where most of the engines excess heat is going.

-jim

Reply to
jim

It used to, but lately the gauge seems to show slightly lower when it's cold outside even after I've been driving for an hour.

Both. I'm basing a lot of this on how my 94 Altima behaved, it would usually warm up fairly quickly, and once the temp guage moved off the cold mark, it would rise to full normal temp very quickly. This one happens very gradually. Also I get warm air almost instantly out of the heater in this car, but it takes a long time to actually get hot, even with the controls set to cold and the fan switched off.

Nope, this is with the controls set to full cold, and after an hour of driving around the city. If I stop and rev the engine for a while both hoses will be warm, but after I start moving again, the lower one returns to about room temperature.

Anyway, I have a new thermostat, so I'll stick it in and be done with it.

Reply to
JM

I had an 86 Pulsar with the same heat problem. I commuted 45 miles one way in the NE US and the heater never seemed to heat properly. My remedy was to use a piece of aluminum flashing and block the lower part of the radiator. I started low and raised it up until I was satisfied with the heat. Of course, I removed it after winter.

Reply to
willshak

Sounds like it is opening at too low a temp.

You can compare the operation of the new thermostat to the old by putting both in a pan of water and watching when they open as you heat the water on the stove. Usually you can get thermostats with different temp ranges. You might want to try a hotter one.

-jim

Reply to
jim

Reply to
Codifus

No, the mileage is quite good thankfully, I usually get around 30 mpg around the city. I have tested the coolant temp sensor and it seems to be within spec as well as I've been able to tell with my meter probes squeezed into the sensor connector. Did your wife's car's sensor being bad trigger the CEL?

I have now replaced the thermostat, and the car does seem to warm up more quickly now, so I'm happy -- hopefully I'll wait a bit less for heat come next winter.

Thanks for the reply,

Reply to
JM

Nope, no CEL, just terrible mpg and somewhat longer warmups.

CD

Reply to
Codifus

Sounds like the thermostat has failed in the open position. I'd replace it before doing anything else. Use OEM if possible, with Stant brand as second choice. Make sure you get one with the correct temperature rating for your car. If you use a cheapie, there is a good possibility you'll be doing it again soon. Don't forget to pick up a gasket. FWIW YMMV

Reply to
NickySantoro

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