Last summer my 99 SE started to run hot when on the highway. I turned the A/C off, and slowed down which brought the gauge down some, but it was still hot. I topped up the coolant reservoir and hoped for the best. Throughout this winter the temp gauge at it's normal mark.

Today, the weather has been very warm, and my temp gauge went up, and the coolant overflow overflowed.

The car an auto, has 100kms (62,000 miles) and the coolant was flushed and changed by the dealer two years ago.

I'm guessing thermostat first. Is this a DIY job?

Anyone have any other suggestions?

Thanks for your input

 

Yes, you can do it yourself, but the thermostat housing can be just a little bit difficult to get at. The best way to gain access to it is from the wheel well. Remove the plastic liner piece and you can get at the lower bolts that hold the housing on.

 

Has the thermostat ever been changed before? When thermostats get weak your car runs cold. *** UNLESS IT'S INSTALLED BACKWARDS!! ***

Be carefull here, check the direction your thermostat is installed. It should upon with the flow, not against it. If it's installed backwards, when the spring gets weak, it cannot open against the coolant flow anymore. If it's in correct as the spring gets weak, it opens to fast and you run cold.

 

The thermostat I bought from the dealer came already installed in a new housing, so it's not possible to install it backwards.

 

How can it come installed in the housing?
The housing is part of the engine block. Unless Nissan uses some very off the wall thermostat setup. I'll have to take a peak in my Haynes manual 2nite.

 

Thermostat can also get stuck in closed position. This way the coolant doesn't flow, resulting in overheating. To test, remove thermostat, place in water, bring to a boil and see if it opens completely. If it doesn't, replace.

 

The thermostat housing is held onto the block with three nuts. The thermostat is an integral part of the housing, it must be changed as a unit.

It is not necessary to remove anything to get at it and remove it. Just take of the hose and remove the 3 nuts and it comes off very easily. I had mine off today when I did my flush.

 

I learned something today!

 

It definately is not the norm and I thought it was a bit strange too but thats the way they do it. Unfortunately it makes the cost of a thermostat higher.

 

Thanks for your input guys

The thermostat is the original part since day one.

I called a dealer. They said CDN $45 ( USD $30 ) for the thermostat. The parts wholesalers didn't have a listing for the stat, so I'm guessing from the price that it includes the housing and stat

Would there be any other reason that the car overheats on the highway?

 

Thanks, Jime, for clarifying that. I must have been thinking of the water pump cover.

d_hammer: If your car is overheating on the highway, the first and cheapest thing to do is change the thermostat. Well, the first thing to do is check to make sure you've got plenty of coolant and don't have a leaking hose, but I assume you've done that already.