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Nissan Repair/2000 Maxima


QUESTION: My car is running at normal temp and doesn't overheat. What is does do is send coolant into the reservoir until it overflows and that's how it's losing water. The fans are working and all coolant system is new including the cap except the water pump. What could be causing this?

ANSWER: Hi Jeff -

Have you checked the thermostat?
Quick check is to remove it and see if you have the same issue.

You mentioned all components are new, this include the radiator?


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QUESTION: Thanks for the reply. Yes both thermostats(I didn't even know it had 2) hsve been replaced and the radiator too. I had to pay a shop to change the second one. Which thermostat should I remove? The intake or the ouput?

ANSWER: Hi Jeff -

You know, I have never heard of any vehicle having 2 stats. All it needs is one for its function.

Puzzling. I would say the intake if there are 2.

Also double check the cap. May be the wrong pressure rating.

Hope this helps -

---------- FOLLOW-UP ----------

QUESTION: Hi Calvin: I have the Nissan manual, technically they call the second thermostat the water control valve. I'd attach the page if I could. The cap has 13.8psi on it and the specs for this car is 11-14 psi. This is the second  cap I've tried. This is the worst car I've ever worked on. The intake thermostat comes with the housing as an assembly (check an auto parts site) so I don't know if I can separate the two without ruining it. Any thoughts? Or prayers :)

Hi Jeff -

Well, you did everything I would do, so I am stumped.

Do you have one of those laser thermometers? Perhaps you can observe the engine when running from cold to warm up. Monitor the temps of the top hose and lower hose. The top should get hot before the bottom, and when the thermostat opens the bottom will start getting warm. Eventually both hoses should be the same temp, and perhaps you can watch at what time the coolant overflows into your reservoir.

BTW, when the engine is cooling down, does the coolant suck back into the engine from the reservoir? It should, as it is designed to do that.

Hope this helps -

Nissan Repair

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Calvin Iwashita


All general car repairs for all models of vehicles, except technicals (overhauls) on A/C systems and transmissions.


16 years as a car mechanic from 1974 to 1990, and still repair cars on the side.


High School and college graduate

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