Should I take out my T-Stat for now to see if it still overheats?

[chrismo240sx]

Im still having overheating issues even after bleeding the system several times. Bleeding the air out helps...( car wont overheat for about 3-4 days, then suddenly does again).

In there now is a thermostat from autozone that i got about 3 months ago when i put the newer motor in (Ka24de). Also replaced water pump as well as radiator and coolant.

Today i bought an OEM T-stat from Nissan because i heard Autozone ones are junk and i should stick with one from Nissan dealership so i did.

So, question is, should i take out the junk autozone one first and run the car around the block a few times to see if it overheats or just install the new OEM one from Nissan?

[IanS]

Often times a perfect cooling system will overheat if the thermostat is removed. Without the thermostat coolant moves so quickly through the radiator that it does not disipate enough heat.

I would suggest installing the OE T-stat.

I would bet you have a different problem all together though. Have you tried replacing the radiator cap? If the cap isn't holding sufficient pressure, it could allow air to enter the cooling system over time, this is why bleeding the system helps for a while. I would replace the cap, and check the sealing surface of the radiator for pitting or buildup that would cause it not to seal.

[chrismo240sx]

its a brand new Mishimoto Radiator....I dont think the cap or radiator would be the problem....

[OutToWinPAHC]

How old is your water pump? Are you belts tights?

[chrismo240sx]

water pump is 3 months old as well, replaced it with the radiator, and the belts are tights, everything is spinning.

[Thoughtful_One]

[QUOTE=FlatBlackIan]Often times a perfect cooling system will overheat if the thermostat is removed. Without the thermostat coolant moves so quickly through the radiator that it does not disipate enough heat.QUOTE]

I have never heard of this. If this was the case, 60% of careless car owners on the road would've blown their HG's by now. Thermostats are designed to fail in the open position. That way, it'll just take longer to warm your engine up, rather than just trapping it within your engine.

If you're taking the time to remove your coolant and pull your coolat outlet off, just eplace the thermostat.

Was it overheating before you touched it?

I see you're running electric fans. Are they hardwired, or temperature controlled?

[chrismo240sx]

Often times a perfect cooling system will overheat if the thermostat is removed. Without the thermostat coolant moves so quickly through the radiator that it does not disipate enough heat.QUOTE]

I have never heard of this. If this was the case, 60% of careless car owners on the road would've blown their HG's by now. Thermostats are designed to fail in the open position. That way, it'll just take longer to warm your engine up, rather than just trapping it within your engine.

If you're taking the time to remove your coolant and pull your coolat outlet off, just eplace the thermostat.

Was it overheating before you touched it?

I see you're running electric fans. Are they hardwired, or temperature controlled?

^^ I thought that sounded weird.

It was overheating yes with the old motor which is how i blew it up from constantly overheating the motor. I thought the gauge was bad but it was reading accurately...figures, Im assuming it had air in the system.

My electric fan (only one) is wired via igniton. When the key is turned to the On position, my fan spins and that works fine too.

I dont understand how both motors can have the same problem when i replaced a lot things.Water PumpRadiator and capThermostatCoolant Temp SensorNew/Fresh coolantBlead System (several times) all when new motor was put in.

So why is it if i bleed the system, it runs fine for a few days (3 on average) then starts to overheat again?

....Another thing is, when it overheats, the coolant resivoir is past the full Line almost ready to overflow out of it. When the motor is off and cold, the fluid is at the Min line. So to me, this is saying thermostat? So the coolant is never circulating into the block?Or am i missing something and it could still be something else?

[Thoughtful_One]

How is your headgasket?

I just noticed you were on Long Island. I am in Centereach.

[chrismo240sx]

oh nice...next town over haha, i pass through every day to work in smithtown

I hope the HG is good...i didnt check it when i put the motor in but my oil isnt milky, there is no smoke or nothing like that....i hope its okay.

[jamie]

its possible that you have a slight headgasket leak to a cooling passage. Your local garage or Snap-On dealer will have a test kit for detecting exhaust gas in the coolant.

[Thoughtful_One]

If your water pump is fine, as well as your radiator, belts, cap, and everything is thoroughly bled, I would check your HG out.

[chrismo240sx]

damn well that blows.....anyway i can personally check it myself without taking the motor apart? Haha yea right...

[Shabbernigdo]

i ran my car all summer with no Thermostat and had no problems even when siting in traffic on 90+ degree days.

The only down side was that it took a bit longer for my car to warm up in the mornings. My temp gauge never goes past the 3rd little bar

[Thoughtful_One]

Well, in fact there is a way. See if you can get a coolant pressure test. I believe they apply pressure to your cooling system, and they check for leaks.

Can also get a leakdown test done, where they apply pressure to one cylinder at a time at TDC to check for how much pressure is lost. If you have bubbles coming out of your radiator, that means you have a bad HG.

Before you do that, just double and even triple check that your O2 pump isn't bad. Where did you buy these things? I've never purchased any engine mechanical stuff from Autozone, but fom what is on the forums, it can be hit or miss.

[chrismo240sx]

yea thursday its going to Nissan for a leakdown test, made an appointment for that

As far as the water pump, i bought that from Nissan, not autozone ha. Only thing i got from autozone was the t-stat and coolant.The radiator i got off ebay.

[vancouverbc]

bleed it again on a steep hill with relief valve and rad cap off and heater on. sit on the bumper the bounce car. takes several attempts to get all the air out.

[chrismo240sx]

Thanks guys. I put the Nissan T-stat in and so far so good...what a difference between the two of them. The autozone one didnt have any rubber seals on it all where the one from Nissan has 2. Also the spring is beefier from Nissan and the little jiggle thing looks like it actually does something rather than looking like its gonna fall off any second like the one from autozone.

So hopefully it was just the T-stat and like i said so far so good. Thanks again.

Oh and Thoughful One....where in centereach are you? If you want we can meet up somewhere sometime. I got a few friends that live there anyways so let me know. Not like its a far drive anyways ha

[IanS]

I have never heard of this. If this was the case, 60% of careless car owners on the road would've blown their HG's by now. Thermostats are designed to fail in the open position. That way, it'll just take longer to warm your engine up, rather than just trapping it within your engine.

Think about it though, even when a thermostat is fully open it still restricts coolant flow by design, that is the nature of the fail safe. By removing the thermostat you open up the orifice to a diameter which it was never designed. This can cause all sorts of issues depending on the engine. Some motors will exibit hot spots internally because the coolant is not pulling heat from the cylinder walls or head. Other times an underheating condition can occur

In the racing world, the use of what is called water restrictors is common. They allow the removal of the thermostat while affording people the ability to tune the water flow through the engine.

[Thoughtful_One]

Yes, I understand what you're saying. It's not really a matter of pulling enough heat off directly that causes hot spots, but rather that not enough heat is being dissipated through the radiator, which inccreases coolant temperature, and lowers it's ability to absorb energy. But yes, I understand what you're saying.

chrismo240sx, sure we can meet one of these days. Catch me on AIM: VivekZ123.