Hi,

My thermostat recently went bad. I'd like to change this myself but aside from loosening a few bolts, I'm mechanically-challenged. Are these steps really necessary?

In the service manual it says,

-Drain coolant from radiator and both sides of cylinder block
-Remove drive belts and idler pulley bracket
-Remove water pump drain plug
-Remove lower radiator hose
-Remove water inlet and thermostat assembly

 

you dont need to remove the belts...our water pumps are internal (behind timing chain cover) and driver by the timing chain (not the belts).

1. drain coolant
2. remove hose from thermostat
3. remove thermostat
4. install thermostat
5. reconnect hose
6. fill radiator

the thermostat is on the passenger side of the engine. its easy to find if you follow the hose from the radiator.

 

That's what I was afraid of. Now if I only knew how to drain the coolant...

 

drain plug on bottom of radiator

 

I'd like to try to pull this off without draining any coolant. If I do this when the car is cold, wouldn't it make sense that all of the coolant would be in the reservoir and the radiator and I could get the thermostat out without having to deal with hot fluid?

 

dont be afraid of draining the radiator,.. like sooner said theres a drain plug,.. once open it will be drained quickly,.. like ur draining ur oil, im sure youve done that before,..

 

you also need to make sure to take out the two drain plugs on the engine block like it says in the service manual. There's one on the right and one on the left.

 

You can do the change without draining all the fluid, but you will inevitably lose some coolant when you pull the hose off the thermostat housing. You should take this opportunity to flush out the old coolant though. It's cheap insurance.

 

In a word:no.

The radiator is normally 100% filled with coolant under all conditions. As the engine warms up, the coolant expands and overflows into the reserve tank. When the engine cools, the coolant contracts, pulls a vacuum, and draws back from the tank. That is why, even when the engine is full cold, there should still be at least a couple of inches of coolant in the reserve tank. (It has a "min" mark molded into the plastic but that can be hard to see.) This is also why it is important to have a radiator cap that seals perfectly to the outer rim of the opening - if there is a leak there, the coolant will not be drawn back in from the reserve tank as the engine cools.

If you have a small amount of air in the radiator, it will harmlessly burp out into the reserve tank the first time the engine gets hot and the radiator will be back to 100% full. If you have a large amount of air, so that it doesn't get expelled during warmup, you will quickly reduce the cooling capacity of the radiator. There is not much wasted volume there.

You really have to at least partially drain the coolant when changing the thermostat or you will make a hell of a mess. If you are not planning to change the coolant then the radiator drain plug is enough, you don't need to worry about draining the block. But as a couple of other people have noted, it's probably a good chance for you to do that too.

 

Thanks for taking the time to explain this!

 

My car overheated today on the freeway! I talked to a local dealer to have it towed there and he said it was probably the thermostat because I had just flushed the coolant after I got new upper and lower radiator hoses. So I get it towed there and homeboy tells me the part is $40 but the labor is only $40 did I get duped cuz courtesy parts has the thermostat for $10.28??????? Do you think he meant labor $70 part $10? It sounds kinda dumb I know but it's written on the invoice as $40 and $40

 

The thermostat costs around $15 and the metal gasket another $8. You are looking at parts of $25. Coming to changing the thermostat, what soonerfan said is absolutely right. I did exactly as decribed by soonerfan, some coolant flows from the block onto the compressor, but hey stick in a towel and you are all set.

 

i did not drain the coolant when i put in a 350z thermostat because i had replaced the coolant about 3 months before. i normally ran a 30/70 (water/coolant) mix so i just replaced what little coolant came out with distilled water.