How to check main thermostat // Where to buy an original Nissan Thermostat?

[Captain Obvious]

I agree about the restrictor washer you mentioned. One of my missions has been to stamp out that no thermostat overheating myth.

 

So, I'm not denying that there are cars out there that overheated after the thermostat was removed, but the reason is definitely not that "the coolant flowed through the block too fast to pick up the heat" or that "the coolant flowed so quickly through the radiator that it didn't have time to cool off." Those are both fundamentally flawed concepts.

 

I would claim that the situations where a car will overheat if the thermostat is removed is because of a second order effect. Stuff like the following:

Reduction in block pressure (as you mentioned) which will lower the boiling point of the coolant.

Increased flow rate resulting in local loop eddy currents in the block which could cause poor coolant refresh in certain areas.

Increased flow rate resulting in cavitation (low pressure) which will lower the boiling point of the coolant.

 

Certainly not because the coolant didn't "have time to do what it was supposed to do". In fact, the exact opposite is true, and is exactly how the thermostat works in the first place!

[siteunseen]

I guess my temp gauge was reading hot because of the friction created by the coolant flowing over the temp sensor in the housing so fast?  

[psdenno]

1 hour ago, siteunseen said:

I guess my temp gauge was reading hot because of the friction created by the coolant flowing over the temp sensor in the housing so fast?  

The molecular interaction between the isotopes in the anti-freeze and the flux capacitor in your glove compartment might be the cause 

Dennis

 

[Zed Head]

1 hour ago, siteunseen said:

I guess my temp gauge was reading hot because of the friction created by the coolant flowing over the temp sensor in the housing so fast?  

Maybe some oil in the coolant would help?  A worthy experiment?  No...?

I count 7 and a half.

[siteunseen]

17 minutes ago, Zed Head said:

Maybe some oil in the coolant would help?  A worthy experiment?  No...?

I count 7 and a half.

I'll just pull the head gasket off and let it mix. 

[Chickenman]

On 1/3/2017 at 8:23 AM, jalexquijano said:

the rad is plugged?????

Yes, happens all the time. My car originally came with a nice 3 core custom Copper rad. Should have been enough to cool it in Death Valley. Unfortunately the PO had never changed the coolant/antifreeze in over 10 years and all the anti-corrossion additives were shot. PO also lived in am area with " Hard " water so rad was clogged with calcium deposits.

The problem didn't " reveal " itself until we got into summer temps of around 30c. And I also got the non-operational AC working two days before leaving on a California holiday. With the warmer temps and the AC working, the clogged radiator could no longer handle the heat load. It started over heating badly with the AC on. Boiling out the rad totally cured the problem. The core tunes came out all nice and sparkling clean and the Rad was able to cool like new.

You can drain the water level down below the top level of the core tubes and then have a look at them with a good flashlight. Quite common to see these core tubes almost totally blocked with calcium, rust and other deposits. If the car was run with straight water or old antifreeze ( 5 years or older ) then corrosion happens rapidly.

Find a good rad shop in your area and have it pressure checked and " Boiled " out. Make sure they do a thorough job.  Take before and after pictures inside drained rad.

[Chickenman]

Picture of an old radiator core before and after a good chemical " Boil out ":

 

 

Edited January 4, 2017 by Chickenman

[Chickenman]

So you currently have a Brand new Nissan 76.5 c ( 170F ) thermostat in the car. That should be good enough for 33C weather easily. I've run my Z in 38C temps in traffic with the AC on and with a 180F temp stat. Car never has cooling issues now,  but that is ONLY after I had the 3 core Rad boiled out and everything in tip top shape.

Is the rad stock? You may want to consider upgrading to a heavy duty aluminum core rad is your old rad is a stocker. MSA and other sell them at reasonable prices. Don't buy the cheapest one. Get something decent and not made in China. Not much point boiling out a stock Rad in your climate.  My situation was different, as rad had a custom triple core already installed. It just needed cleaning.

Edited January 4, 2017 by Chickenman

[Chickenman]

If you cannot find a 160 F thermostat from Nissan, and you still want to run one, you can use a thermostat for a mid 70's Mopar slant 6. There a bajillion of these things made and 160F stats are fairly easy to find. Order a 160 stat for a 1975 Dart 225 slant 6. Rock Auto has them. I used Mopar 160F thermostats all the time im my racing Datsuns back in the 1970's.

Despite my earlier reservations about Stant quality control, they are still a decent product. Not a good as 20 years ago when they were made in the USA, but a good second choice if an OEM Nissan 16 F stat can't be found. 

https://www.rockauto.com/en/catalog/dodge,1972,dart,3.7l+225cid+l6,1088434,cooling+system,thermostat,2200

Stant Premium 160 F #45356 = $4.02 USD

Gates Premium 160F #33006S = $3.87 USD

 

 

 

Edited January 4, 2017 by Chickenman

[siteunseen]

Do you have a thermostat in your race car @Jeff G 78?

I understand the eddy loop you speak of CO. I have a river thankfully running through here. The slews are stagnet but the main channel is clean. 

[Jeff G 78]

35 minutes ago, siteunseen said:

Do you have a thermostat in your race car @Jeff G 78?

I started out with a gutted thermostat (Nissan T stat with the valve removed) and the car ran too cold.  I then switched to a Fail Safe thermostat and haven't had any problems since.  I run a stock mechanical fan and a 3 row copper radiator.  I will likely close off quite a bit of the grill opening for better aerodynamics.  The grill opening is WAY too big for racing conditions.

[Mark Maras]

 I've run mine without a thermostat. I don't remember it overheating without it, I remember low temps in the engine and heater. It was one of those out in the boondock repairs, a long way from anywhere in eastern Oregon. Basic tools, a short case box for a gasket, beer from the short case for coolant and the need to get to another beer store and then a parts store. Found the beer, drove it back to Portland, sans thermostat. It turned out to be a memorable trip. Not something I would recommend but it beats the hell out of running it with a thermostat that's stuck closed. No damage to the engine at all.