My 1995 Nissan 4x4 with a V6 shows that it is running very cool.

Is this a thermostat or sensor problem?

What are trhe effects of running too cold?

Does it increase my fuel consumption?

The thermostat is probably pulled. Where do you live? Is it cold where you are at?

There are no bad effect running a cold engine. You'll just never have much heat. if it's cold outside and your engine is running cold you need use light oil. When oil is cold it's thicker, therefore in the winter you need to run a lighter oil.

Only time a cold running engine will effect fuel consumption is when you are at idle. Due to the higher idle speed.

Is the gauge sitting inbetween the two middle lines? Anywhere in that range is OK.

Mine used to only get up to the 1/4ish area and never to normal. I replaced the t-stat with a 180 degree one and it brought the heat right up to the normal mark and it ran better for sure.

I suspect the same thing as LordBiotre; the thermostat may have been removed by the previous owner as a redneck cure for an overheating problem.

If running cold was a good thing, there would be 90º thermostats. Normal operating temperature is designed to help atomize the fuel mixture as it passes through the intake manifold. That is why coolant runs through the 4-banger intake.

My advice would be to pick up a t-stat and gasket and pop it in next chance you get. Make sure you put it in facing the correct direction (flow) and with the "up" side up.

Mine runs great, it's just that a friend was riding with me one day and pointed out how cool mine was, with the needle basically staying in the bottom 1/4 of the range.

Its just a worn out t-stat then, IIRC that a new one was about $10 and only takes about 20 minutes to install.

quote:

1/4 of the range

My 95 alway runs at that temp.

That doesnt mean its correct.

My gauge never worked correctly. I have an aftermarket one now. Much better.

well i have a 96 hardbody 4 cylinder and it runs at a 1/4 to.. if it is running fine and not over heating then it should be working just fine.. if u have an aftermarket one its not gunna make it run anybetter its just gunna give u a different reading maybe where it lys on the leadle but its still the same temp.. the T-stat just reads the temp not improve it..

The t-stat controls how hot the motor gets, it does not read the temp. A hotter t-stat will affect the temperature of the coolant and raise or lower it accordingly.

Yes-ish

The Thermostat is just a spring and plunger that responds to heat. If the coolant is cold then the thermost closes (not all the way) until the water is warm enough to effect the spring causing the thermostate to open up and allow the water to flow more easily (faster) through the block.

Over time the spring on a thermost will wear out causing it to remain in the open position when it should be closing some to maintain proper coolant temperature.